Effectiveness of a Multi-component Sleep-Mood Group Intervention on Improving Insomnia in University Students – a Pilot Randomized Controlled Trial

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Pape, Sophie Jonker, Liia M.M. Kivelä, Annemieke van Straten, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4617700/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 05 Nov, 2024 Read the published version in BMC Psychology → Version 1 posted 4 You are reading this latest preprint version Abstract Background: Sleep and mental health problems are very common in university students. The objective of this study was to assess the effectiveness of a multi-component sleep-mood intervention on improving sleep and mental health in university students with clinically significant insomnia symptoms, and to investigate possible mediators. Methods: Thirty-five participants were randomized to the Sleep Mood Intervention: Live Effectively (SMILE) intervention (n= 23), or wait-list group (n= 12). SMILE is a multi-component group therapy and includes elements of cognitive behavioral therapy for insomnia (CBT-I), mindfulness, and lifestyle modifications, in four weekly two-hour sessions. The primary outcome was insomnia severity. Secondary outcomes were severity of depression and anxiety, and quality of life (QoL). Dysfunctional beliefs and attitudes about sleep and pre-sleep arousal were assessed as mediators. Results: Intention-to-treat analysis showed significant time x treatment interaction on insomnia symptoms ( p =.021, partial η² =.152), with significantly lower insomnia severity for SMILE compared to waitlist at post-test. No significant effects were found on depression, anxiety, and QoL. Dysfunctional beliefs mediated the effect on insomnia severity, but pre-sleep arousal did not. Conclusions: This integrated group intervention is associated with reductions in insomnia symptoms in university students. Since no significant effects were detected on mood and QoL, future studies with larger sample size may explore the effects of this intervention on these outcomes. Trial Registration: Registry: Overzicht van Medisch-wetenschappelijk Onderzoek Registration number: NL-OMON46359 Date of registration: September 18th, 2018 insomnia mood mindfulness university students group intervention Figures Figure 1 Figure 2 1. Background Insomnia is a major public health problem and can, if untreated, lead to a range of physical and mental health problems, such as hypertension, obesity, cardiovascular disease, depression and anxiety disorders ( 1 – 3 ). Sleep problems are especially common among university students ( 4 , 5 ). A systematic review of the prevalence of insomnia in 16,748 university students found a weighted mean of 18.5% (ranging from 9.4–38.2%), which was substantially higher than in the general population at 7.4% ( 6 ). The increased prevalence of insomnia may be attributed to numerous challenges in the lives of students. University students face high expectations of their education and future careers, have to develop greater personal independence, and face the challenge of balancing social activities, part-time jobs, and self-directed studying, all while contending with financial pressure due to rising tuition fees and living expenses ( 7 ). These generally conflicting demands can lead to excess stress among students, making them a high-risk population for both sleep disturbances and mental health complaints ( 8 ). Moreover, university students are in an age group that is particularly vulnerable to the onset of psychopathology ( 9 ). A growing body of literature supports the effectiveness of psychological interventions for insomnia, especially cognitive behavioral therapy for insomnia (CBT-I). During CBT-I, patients learn to identify and modify maladaptive thoughts, attitudes, and behaviors, by utilizing psychoeducation, cognitive restructuring, stimulus control, sleep restriction, and relaxation techniques. It has been shown effective in both individual and group face-to-face formats as well as in online formats ( 10 – 12 ), and even for those with subthreshold insomnia ( 13 ). About 70–80% of people with insomnia benefit from CBT-I ( 14 ). Furthermore, sleep interventions including CBT-I show smaller effect sizes in students than in the general adult population ( 10 , 15 , 16 ). Chandler et al. almost exclusively included CBT-I studies and found a moderate effect size ( d = 0.55), while Saruhanjan et al. and Kodsi et al. included more studies with different types of sleep interventions, such as sleep education and relaxation training, and found moderate effects on sleep, with effect estimates of 0.61 and 0.51, respectively. A possible explanation for the smaller effect size in students may be that several interrelated factors are especially relevant in the lives of students that are insufficiently addressed in current interventions. For instance, issues relevant to students include perfectionism, stress-sleep reactivity, poor psychological flexibility and coping skills, which are known to contribute to the development and maintenance of sleep problems ( 5 , 17 – 19 ) and may have to be emphasized more in a student population. Students may require a tailored approach that considers their specific challenges and circumstances. Interventions targeting multiple behaviors and skills simultaneously may therefore be more effective than single-component treatments to promote better sleep among students. A promising add-on to CBT-I is mindfulness-based interventions. Mindfulness is a practice aiming to direct an individual’s attention to the present moment without judgement and increase awareness of internal and external experiences ( 20 ). It is used to decrease stress and increase mental well-being through exercises such as breath regulation and body-scan meditation ( 21 ). A recent meta-analysis of seven RCT’s showed that mindfulness-based stress reduction significantly improved sleep quality, depression, and anxiety among adult insomnia patients ( 22 ). Another study among adolescent girls examined the effectiveness of a multi-component mindfulness-based group intervention and found that the intervention was feasible and resulted in moderate improvements in subjective sleep ( 23 ). Therefore, in order to tackle the stress-related factors mentioned above that are intertwined with the lives of students, mindfulness-based techniques might be a fruitful add-on to sleep interventions. A brief group multi-component sleep-mood intervention combining CBT-I and mindfulness practices with lifestyle components, the Sleep Mood Intervention: Live Effectively (SMILE) intervention, was developed to target sleep and mood in university students, taking into account the needs of this target group. The objective of the present study was to assess the effectiveness of the SMILE intervention in university students with sleep complaints. The primary outcome was insomnia severity. The secondary outcomes were symptoms of depression, anxiety and quality of life. Given the close relationship between sleep and mental health, we hypothesized that SMILE improves all outcomes. Secondly, we explored the mechanisms of change, namely whether the treatment effect on insomnia was mediated by dysfunctional beliefs about sleep and levels of pre-sleep arousal. Both are factors that have been previously assessed as mediators in other intervention studies on sleep outcomes ( 24 ). 2. Methods 2.1 Study Design The current research is a pilot randomized controlled trial to determine the effectiveness of a multi-component sleep-mood intervention (the SMILE intervention; Sleep Mood Intervention: Live Effectively) in university students on reduction of insomnia symptoms comparing two groups: the SMILE intervention group and a waiting list control group with an allocation ratio of 2:1. The study included a baseline period of one week, an intervention period of four weeks, and a post-intervention period of one week. Participants in the wait-list condition received the SMILE intervention after six weeks. The study was approved by the Medical Ethical Committee Leiden The Hague Delft (METC-LDD) in the Netherlands (NL64330.058.17, September 18th, 2018) and was registered at the Overzicht van Medisch-wetenschappelijk Onderzoek register (registration number: NL-OMON46359) on September 18th, 2018. This study was carried out in accordance with the Declaration of Helsinki and the guidelines of Good Clinical Practice (GCP). 2.2 Recruitment and Participant Screening Participants were recruited between September 19th, 2018 and February 11th, 2020. Recruitment took place at Leiden University through posters placed in university buildings, on social media via postings in student groups, as well as through referrals from other studies. The recruitment process consisted of two stages. First, pre-screening of participants was performed through online questionnaires, including the Insomnia Severity Index (ISI) with a cut-off of ≥ 10, to identify students with current sleep problems. Second, all participants deemed eligible through the pre-screening procedure and willing to participate in the study completed a face-to-face diagnostic interview with the M.I.N.I Plus International Neuropsychiatric Interview ( 25 ) confirming that the participants met the full inclusion and exclusion criteria. Inclusion criteria were 1) self-reported sleep complaints with ISI score of ≥ 10, representing clinically significant insomnia ( 26 ); 2) being enrolled as a university student 3) being 18 years or older; 4) adequate proficiency in both written and spoken English; and 5) willingness to participate in a four-week group intervention program and giving informed consent. Students were excluded under the following circumstances: 1) in the presence of clinically significant psychopathology (as based on DSM-IV criteria from the M.I.N.I. diagnostic interview) regarding: current Major Depressive Disorder, Bipolar Disorder, Panic disorder, Social Anxiety Disorder, Post-traumatic Stress Disorder, Attention Deficit Hyperactivity Disorder, Eating disorders, and Psychotic disorders; 2) in the presence of a sleep disorder such as narcolepsy or sleep apnea; 3) in the presence of acute somatic illness that might interfere with the intervention; 4) currently (past month) using medication known to influence sleep (e.g. hypnotics, anxiolytics, antidepressants, stimulants, and > 0.5mg melatonin per day), except for antidepressant treatment which if it was started more than 3 months prior to study enrollment and dosage was stable then the participant was included; 5) current substance use dependency; and 6) concurrent psychotherapy (e.g. CBT, including past CBT for sleep or depression). An overview of the study design can be found in Fig. 1. The online eligibility screening was completed by 91 students, of which 19 were excluded due to scoring < 10 on the ISI. Sixty-six students were invited to the intake and completed the psychiatric interview. After this intake, 31 students were excluded due to exclusion criteria during or after the initial screening. Thirty-five people were randomized into SMILE (n = 23) or waitlist group (n = 12). Randomization took place by an independent researcher with a 2 : 1 ratio for intervention : waiting list, respectively. This was done for clinical purposes, in order to provide help to more students. Groups could start when enough participants had been enrolled to form groups, this took on average 4–6 weeks to achieve. 2.3 Intervention The SMILE intervention (Sleep Mood Intervention: Live Effectively) is a group therapy intervention with a duration of four weeks (two-hour sessions weekly). Each session covers different topics: Session 1) Sleep education, sleep hygiene, stimulus control, and sleep restriction; Session 2) negative thoughts; Session 3) relaxation techniques and mindfulness; Session 4) lifestyle issues. Further information on the content of the SMILE intervention can be found in Table 1 . Therapists were trained Master-level psychologists. They were instructed to follow the intervention protocol; for the fourth session (lifestyle issues), a range of issues was covered taking into account the needs of each group. Each group had a maximum of six participants. Table 1 Content of the SMILE intervention Session Content Session 1 Introduction – Sleep education and hygiene - Biology of sleep, effects of sleep deprivation, importance of sleep in physical and mental wellbeing - Sleep hygiene (behaviours that promote healthy sleep), e.g. sleep schedule, avoiding daytime napping, and limiting coffee and substance use - Stimulus control (strengthen the bed as a cue for sleep) - Sleep restriction (limiting the hours in bed) Session 2 The Mind – Dealing with negative thoughts - Concept of cognitive arousal and its impact on sleep - Cognitive behavioural techniques - Dysfunctional thoughts about sleep or non-sleep related - Constructive worrying and positive refocusing Session 3 The Body – Relaxation and Mindfulness - Dealing with stress and arousal - Deep (diaphragmatic) breathing - Progressive muscle relaxation - Mindfulness practice directed at challenging automatic reactions to stress, increasing awareness to the present moment, and letting go of negative thoughts associated with sleep Session 4 The Whole – Lifestyle Issues - Cognitive and behavioural patterns influencing sleep - Substance use (alcohol, drugs, smoking) - Lifestyle topics such as flexibility and planning, perfectionism, burnout, diet, self-acceptance - Summary and relapse prevention plan 2.4 Measurements Assessment Points Assessments took place at baseline (T0) and after five weeks (T1). After T1, all participants in the waitlist control group were offered the SMILE intervention, which finished the controlled element of the trial. Demographic characteristics were assessed at baseline. Primary Outcome Insomnia complaints were measured with the 7-item ISI ( 26 ). A higher score suggests more insomnia severity in the past week or past two weeks, with total scores ranging from 0 (no insomnia) to 28 (severe insomnia). A cut-off score of 10 was determined as optimal to indicate clinical levels of insomnia and was therefore used as a cut-off for inclusion of participants ( 26 ). The ISI is a widely used measure with adequate internal consistency and reliability ( 27 ). The internal consistency in this sample at baseline was moderate at Cronbach’s α = .65. Secondary Outcomes The Beck Depression Inventory II is a 21-item questionnaire which measures depressive symptoms in the preceding two weeks. Total scores are ranging from 0 (no depression) to 63 (severe depression). This inventory is shown to be a sensitive and reliable measure ( 28 ). The internal consistency in this sample was good at Cronbach’s α = .84. Anxiety symptoms were assessed using the anxiety subscale of the Hospital Anxiety and Depression Scale (HADS-A) ( 29 ). Seven items are assessed to measure anxiety over the past week. The total score ranges from 0 (no symptoms of anxiety) to 21 (severe symptoms of anxiety). Internal consistency of the HADS-A in this sample was moderate, with Cronbach’s α = .76. Quality of life was measured with the Quality of Life Enjoyment and Satisfaction Questionnaire - short form (Q-LES-Q-sf) ( 30 ). The Q-LES-Q contains 16 item-domains, including physical health, mood, work, social relations, ability to function in daily life and more. Totals scores range from 14 to 70, with higher scores indicating better quality of life. The internal consistency in our sample was satisfactory at α = .78. Other Outcomes Dysfunctional Beliefs and Attitudes of Sleep (DBAS-16) were assessed as a mediator variable. The DBAS consists of 16 items evaluating beliefs, expectations, and attitudes about sleep complaints ( 31 ). Each item statement is rated on a scale from 0 (strongly disagree) to 10 (strongly agree), and higher scores indicate more dysfunctional beliefs and attitudes. The questionnaire is found to have adequate psychometric properties ( 31 ). The internal consistency in our sample was satisfactory at Cronbach’s α = .77. Sleep-related arousal was measured with the Pre-Sleep Arousal Scale (PSAS), which measures subjective arousal before sleep in 16 items ( 32 ). The questionnaire measures two subscales: cognitive arousal and somatic arousal. We reported the sum score of the PSAS (ranging from 8 to 40). Higher scores indicate more pre-sleep arousal. The internal consistency was good with Cronbach’s α = .87. 2.5 Deviations from the Study Protocol A total sample size of 72 participants was required to have sufficient power (0.80) to be able to detect differences of a small effect size ( d = 0.17) using alpha < 0.05 and repeated measures ANOVA. This was calculated using the G*Power v3.1.9.2. tool. However, there was a premature termination of the study due to the COVID-19 pandemic. Organization of the group session in an online format was not possible, not only due to a lack of resources, but also as it would have resulted in fundamental changes to the intervention content. After the COVID-19 break out (March 2020), the recruitment stopped. Furthermore, in the study protocol, subjective sleep quality assessed with a sleep diary was listed as another primary outcome measure. However, due to large amounts of missing data (14 participants (40%) had sufficient data at both pre-test and post-test) data imputation was not possible and therefore this outcome was not analyzed and not reported. 2.6 Statistical Analysis All analyses were performed as intention to treat in IBM SPSS Statistics (version 27.0). Analyses were carried out using a 0.05 α-level (two-tailed). Baseline differences between the two groups were tested with independent samples, t-tests for continuous variables, and chi-square tests for categorical variables. Data was checked for outliers and for assumptions for parametric analyses. Last observation carried forward was used to impute missing values at post-test (n = 2). The primary and secondary outcomes were analyzed using a repeated measures analysis of variance (ANOVA), with condition (SMILE versus waitlist) as between-subjects factor, and time (T0 versus T1) as within-subjects factor. The magnitude of the effect for the within-group change and difference between groups at post-test was calculated using Cohen’s d, with 0.2, 0.5 and 0.8 as small, moderate and large effects, respectively ( 33 ). Participants were categorized as a remitter when the ISI score at post-test was below 10 points, and participants were categorized as treatment responders when there was a reduction in the total ISI score of ≥ 8 points ( 26 ). For mediation analysis of DBAS and PSAS, Hayes’ ‘PROCESS’ tool (model 4) was used with 10.000 bootstrap re-samples ( 34 ). Group allocation was the independent variable, insomnia severity the dependent variable, and DBAS and PSAS the mediator variables, in two separate models. We used the pre- to post-test change scores of the ISI to correct for baseline values. Mediation was tested using the 95% confidence interval of the indirect effect ( path ab ). 3. Results Participant’s demographic characteristics can be found in Table 2 . The mean age of the sample was 22.8 (SD = 4.2) and 74.3% of the participants were female. There were no significant differences between the groups at baseline (all p ’s > 0.05). Even though none of the differences were statistically significant, the intervention group had a higher proportion of female participants (82.6%), higher proportion of international students (65.2%), and higher proportion of students consuming alcohol (78.3%) compared to the control group. The study compliance was very high, as 94% of all students completed T1. Compliance with the sessions in the intervention group was also high, since almost all students in the intervention group (n = 21, 95.5%) attended all four sessions, and one student attended the first three sessions. Two students (5.7%, N = 35) dropped out of the study, one in each group (one due to the death of a family member and one due to unknown reasons). Table 2 Demographic characteristics of the study sample (n = 35) SMILE Waitlist Characteristic n = 23 n = 12 Age, mean (SD), years 23.5 (4.9) 21.4 (1.4) t ( 33 ) = -1.44, p = .06 Gender, n (%) Female 19 (82.6) 7 (58.3) Male 4 (17.4) 5 (41.7) Χ² ( 1 ) = 2.43, p = .12 Nationality, n (%) Dutch 8 (34.8) 7 (58.3) Other 15 (65.2) 5 (41.7) Χ² ( 1 ) = 1.79, p = .28 Relationship status, n (%) In a relationship 6 (26.1) 5 (41.7) Married or cohabitating 2 (8.7) - Single 15 (65.2) 7 (58.3) Χ² ( 2 ) = 1.71, p = .43 Medication, n (%) No medication 19 (82.6) 11 (91.7) Antidepressants 1 (4.3) - Non-psychoactive medication 1 (4.3) 1 (8.3) Iron supplements 2 (8.7) - Χ² ( 3 ) = 1.86, p = .60 Alcohol use, n (%) Yes 18 (78.3) 7 (58.3) Χ² ( 1 ) = .22, p = .26 No 5 (21.8) 5 (41.7) Insomnia Severity (ISI), mean (SD) 14.3 (3.1) 15.7 (5.4) t ( 33 ) = 0.98, p = .12 Depressive symptoms (BDI II), mean (SD) 11.9 (7.1) 11.5 (6.0) t ( 33 ) = -0.15, p = .67 Anxiety symptoms (HADS-A), mean (SD) 8.9 (3.3) 8.8 (4.7) t ( 33 ) = -0.06, p = .50 Quality of Life (Q-LES-Q), mean (SD) 54.7 (13.6) 61.2 (10.1) t ( 33 ) = 1.45, p = .37 Pre-Sleep Arousal (PSAS), mean (SD) 42.6 (8.8) 42.1 (10.6) t ( 33 ) = -0.16, p = .41 Dysfunctional Beliefs and Attitudes about 73.2 (19.8) 78.4 (20.8) t ( 33 ) = -0.47, p = .97 Sleep (DBAS), mean (SD) Note. Non-psychoactive medication: Ibuprofen n = 1; Antibiotics n = 1. 3.1 Treatment Effects on Insomnia Severity Repeated measures ANOVA was conducted to test whether the SMILE intervention was effective in reducing insomnia severity compared to a control group in an intention-to-treat analysis (n = 35). There was a significant time x treatment effect F ( 1 , 33 ) = 5.91, p = .021, η2 = .152, in the unadjusted model. The main effect of time was significant F ( 1 , 33 ) = 18.46, p < .001, η2 = .359. The main effect of group allocation was non-significant F ( 1 , 33 ) = 3.31, p = .078, η2 = .091. Sensitivity analysis with complete cases showed similar results, with a significant interaction effect of F ( 1 , 31 ) = 5.74, p = .023, η2 = .156. Those who received the SMILE intervention had significantly lower insomnia severity (M = 10.7, SD = 4.8) compared to the waitlist at post-test (M = 14.7, SD = 4.9), t ( 33 ) = 2.33; p = .026, 95% CI [.51 to 7.52], representing a large effect with Cohen’s d = .83, 95% CI [.098 to 1.55]. 3.2 Clinically Significant Improvement of Insomnia In the SMILE group, 47.8% of the students were treatment remitters with a post-test insomnia severity score of less than 10, compared to 16.7% in the waitlist group [ X 2 (1, N = 35) = 3.28, p = .07]. In the SMILE group, 9.4% of students (n = 3) were treatment responders with a reduction in total ISI score of ≥ 8 points, compared to no responders in the waitlist group[ X 2 ( 1 , 35 ) = 1.5, p = .22]. 3.3 Treatment Effects on Secondary Mental Health Outcomes Results of repeated measures ANOVA indicated that the differences in anxiety symptoms between SMILE and waitlist group from T0 to T1 were non-significant F ( 1 , 33 ) = 2.21, p = .147, η2 = .063. Post-test differences were non-significant as well with t ( 33 ) = .803, p = .428, and a Cohen’s d = .29, 95% CI [-.42 to .99]. For depressive symptoms, repeated measures ANOVA with square root transformed data showed that there was no significant interaction effect for depression either, F ( 1 , 33 ) = 2.95, p = .095, η2 = .082. Mann-Whitney U test on the skewed BDI scores revealed no significant differences between SMILE and waitlist condition at post-test, U = 101.5, p = .204. Results of repeated measures ANOVA on quality of life furthermore revealed no interaction effect on quality of life, F ( 1 , 33 ) = 2.29, p = .139, η2 = .065. Post-test differences between the two groups were also not significant t ( 33 ) = − .349, p = .71, with Cohen’s d = − .124, 95% CI [-.82 to .56]. Table 3 presents the results for primary and secondary outcomes. Figure 2 shows the interaction plots for pre- and post-test means of the main outcomes. Table 3 Primary and secondary outcomes by treatment groups SMILE (n = 23) Waitlist (n = 12) Pre-test Post-test Cohen's d T0-T1 Pre-test Post-test Cohen’s d T0-T1 Time Group x Time Primary outcomes Mean (SD) Mean (SD) Pre-Post Mean (SD) Mean (SD) Pre-Post F p F p η2 Insomnia Severity (ISI) 14.3 (3.1) 10.7 (4.8) 0.89 15.7 (5.4) 14.7 (4.9) 0.20 18.46 .000 5.91 .021* .152 Secondary outcomes Anxiety symptoms (HADS-A) 8.9 (3.3) 8.2 (3.6) 0.20 8.8 (4.7) 9.3 (4.0) 0.11 .17 .681 2.20 .681 .005 Depressive symptoms (BDI II) 11.9 (7.1) 11.0 (8.2) 0.11 11.5 (6.0) 12.8 (5.1) 0.23 .003 .958 2.95 .095 .082 Quality of life (Q-LES-Q) 54.7 (12.8) 56.1 (17.6) 0.09 61.2 (10.2) 54.0 (15.8) 0.54 .992 .327 2.29 .139 .065 Pre-Sleep Arousal (PSAS) 42.5 (9.0) 35.7 (10.1) 0.71 43.5 (10.0) 43.1 (10.5) 0.04 3.76 .062 3.76 .062 .089 Dysfunctional Beliefs and Attitudes about Sleep ( DBAS) 81.8 (19.8) 67.9 (13.6) 0.82 78.4 (20.8) 79.8 (19.1) 0.07 4.05 .053 6.20 .018* .167 * p < .05 3.4 Mediation Analysis The mediation analysis included group allocation as the independent variable and insomnia severity as the dependent variable. The pre-to-post change scores of DBAS and PSAS were included as mediator variables in two separate models. For intention-to-treat analysis, the total effect ( path c ) of group allocation on insomnia severity was significant with b = -2.61, 95% CI [-4.79 to -0.43]. As shown in Table 4 , the effect of the SMILE intervention on insomnia severity was mediated by dysfunctional beliefs with b = 1.12, 95% CI [-2.58 to − .06], meaning a decline in dysfunctional beliefs was related to a decline in insomnia severity. 54.7% of the variance was explained by the mediator DBAS. Pre-sleep arousal did not significantly mediate the effect of the SMILE intervention on insomnia severity with b = − .68, 95% CI [-2.12 to .03]. 50.9% of the variance was explained by the mediator PSAS. Mediation analysis for completers showed the same pattern as for intention to treat. Table 4 Dysfunctional beliefs and attitudes and pre-sleep arousal as mediators of the intervention effect on insomnia severity M DV Effect of independent variable on mediator ( a ) Effect of mediator on dependent variable ( b ) Indirect effect ( ab ), [95% CI] Direct effect ( c' ) Total effect ( c ) DBAS ISI b = 15.33, t= -2.51, SE = 6.10 * b = .07, t = 2.59, SE = 0.28 * b= -1.12, [-2.58; -0.06] * b= -1.49, t= -1.40, SE = 0.65 b= -2.61, [-4.79 to -0.43] * PSAS ISI b= -6.14, t= -1.77, SE = 3.47 b = .11, t = 2.15, SE = 0.05 * b= -0.68, [-2.12; 0.03] b= -1.93, t= -1.81, SE = 1.07 b= -2.61, [-4.79 to -0.43] * Note : M = Mediator variable, DV = Dependent variable, Independent variable = Group allocation, DBAS = Dysfunctional Beliefs and Attitudes about Sleep Scale, PSAS = Pre-Sleep Arousal Scale, ISI = Insomnia Severity Index * p < .05 4. Discussion We found that the SMILE intervention, compared to the waitlist control group, significantly reduced insomnia severity. This finding is in line with previous research in university students, that has shown how the individual components of the SMILE intervention, such as CBT and mindfulness, are beneficial in improving sleep ( 10 , 11 , 35 ). Recent meta-analyses showed that brief psychological interventions, especially CBT-I, had moderate to large effects in improving sleep outcomes in students ( 10 , 11 , 16 ), and mindfulness-based stress reduction had moderate effects on sleep quality in insomnia patients ( 22 ). Also, the combination of both CBT and mindfulness as an integrated intervention in six weekly sessions was associated with improvements in sleep outcomes and a reduction in sleep-related arousal in adults with primary insomnia ( 36 ). A recent systematic review concluded that multi-component interventions show moderate effects in improving university students' sleep and mental health ( 15 ). The effect size for insomnia severity in our study was η2 = .152, which corresponds to d = 0.84, and was larger than the moderate effect size of d = 0.55 reported by Chandler et al. ( 15 ). No significant effects were found on any of the secondary outcomes. Mental health symptoms either showed a slight positive trend of improvement or remained stable in the intervention group but generally slightly declined in the waitlist group, as shown in Fig. 2 . That the improvement in mental health symptoms was not significant is probably a result of low statistical power, but further research needs to verify this in a larger sample. Still, effect sizes for depression and anxiety severity in our study were d = 0.60 and d = 0.14, respectively. Prior research has shown large improvements in depression and anxiety symptoms after mindfulness-based stress reduction in adults ( 22 ). Recent systematic reviews and meta-analyses overall have shown that the effects of CBT-I are moderate to large on mood symptoms and moderate on quality of life ( 37 , 38 ). In university students, however, the effects of single-and multi-component sleep interventions were smaller than in adults on the outcomes anxiety with SMD = -0.23 and depression with SMD = -0.30 ( 15 ). Similar to our findings, no improvements in anxiety symptoms were found after a multi-component mindfulness-based group sleep intervention in an adolescent population ( 23 ). These findings show that such sleep interventions might have more specific effects - only on sleep outcomes - in younger populations. The mediating effect of the cognitive and arousal processes was examined. Dysfunctional beliefs about sleep significantly mediated the effects of the intervention on insomnia severity. This finding is in line with most previous literature, supporting the evidence of dysfunctional beliefs as a mediator of insomnia symptom improvement following CBT-I ( 39 – 43 ). However, the current study design warrants cautious interpretation of the mediation results since we only established a co-occurring change of dysfunctional beliefs and change of insomnia severity. Therefore, although the finding is plausible we emphasize the need for more rigorous mediation research using multiple time points to elucidate the causal mechanisms underlying these associations. Dysfunctional beliefs are an important factor in the treatment of insomnia since it plays a role in increased anxiety around sleep and engagement in sleep-disrupting compensatory behaviors ( 24 ). Future research might look into the specific beliefs that may change during insomnia treatment, for instance by means of Network Intervention Analysis ( 44 ). In contrast, pre-sleep arousal did not significantly mediate the effects of the intervention on insomnia severity. In a previous systematic review and meta-analysis, five studies were summarized which included hyperarousal outcomes and they concluded that only limited evidence was found for hyperarousal as a mediator for CBT-I ( 42 ). It remains challenging to establish causal links between treatment, mechanisms, and outcomes, especially in multi-component interventions such as the SMILE intervention. Still, future studies should consider a range of cognitive factors (e.g., sleep self-efficacy, locus of control) and behavioral factors (e.g., variability in sleep-wake time), as suggested by Schwartz and Carney ( 24 ), and should utilize rigorous designs with multiple measurements, in order to get a better understanding of how CBT-I works. The most important limitation of the study is the small sample size leading to decreased statistical power. Furthermore, as mentioned before, adding a midpoint measurement would have given more information about temporal precedence in the mediation analysis. A final limitation is that the results may not be generalizable to other populations since our sample included a relatively heterogenous group of mostly female students. Nonetheless, the study has some strengths. The study design is a randomized controlled trial and analyses were done with the intention to treat-approach. Furthermore, study drop-out was very low since only two participants (5.7%) dropped out. Adherence to the sessions was high (95.5% attending all sessions), although this is partly attributable to the flexibility of the group leaders, who provided a brief substitute session in case a participant was unable to attend the group session. Still, it is a good indicator of the acceptability of the intervention and feasibility of the current intervention design. The short duration makes this type of multi-component intervention easy to implement in a student population. 5. Conclusions In conclusion, this study has shown that students with insomnia can benefit from a four-week group intervention in improving their insomnia symptoms. Multi-component interventions tailored to the needs of university students offer a promising path in improving sleep problems in this population at risk for both sleep and mental health disturbances. Still, the low number of treatment responders and low effect size in secondary outcomes point towards further investigation. The current treatment might be further examined in a series of case studies in order to deduce what elements need to be added or expanded to make the treatment more effective. Additionally, it would be worthwhile to investigate alternative ways to improve sleep in students. Even though the adherence rate was high in this trial, the recruitment period was long and the recruitment rate was low, indicating that not many students were willing or able to engage in the intervention. A more accessible and scalable alternative to face-to-face group therapy might be internet-delivered interventions. To summarize, future research should include larger samples, multiple measurement moments to formally test mediation, and explore different forms of delivery to further examine the effectiveness of multi-component sleep interventions. Abbreviations ANOVA Analysis of Variance BDI Beck Depression Inventory CBT-I Cognitive Behavioral Therapy for Insomnia DBAS Dysfunctional beliefs and attitudes about sleep ISI Insomnia Severity Index HADS-A Hospital Anxiety and Depression Scale - Subscale Anxiety RCT Randomized controlled trial PSAS Pre-Sleep Arousal Scale QoL Quality of Life Q-LES-Q Quality of Life Enjoyment and Satisfaction Questionnaire Declarations Ethics Approval and consent to participate Ethical approval was attained on September 18th, 2018, from the Medical Ethical Committee Leiden The Hague Delft (METC-LDD) in the Netherlands with reference number NL64330.058.17. All participants in the study gave informed consent. This study was carried out in accordance with the Declaration of Helsinki and the guidelines of Good Clinical Practice (GCP). Consent for publication Not applicable. Availability of Data and Materials The datasets generated and analyzed during the current study are available from the corresponding author on reasonable request and in the DataverseNL repository after study completion. Competing interests The authors declare that they have no competing interests. Funding The study was supported by funds of the Clinical Psychology Department of Leiden University. The contract of Laura Pape is funded by the Dutch Research Council (NWO) as part of the BioClock Research Project (project number 1292.19.077). Author’s Contributions NA is the principal investigator and wrote the study outline for the grant application. NA and LK developed the treatment protocol, contributed to the study design, carried out the interventions, recruitment, and data collection. SJ and LP performed the statistical analysis. LP drafted the manuscript. NA, LK, and AvS revised the manuscript. All authors approved the final version of the manuscript. Acknowledgments The authors would like to thank Katerina Petsi, Liv Henrich, and Akrivi Kyrgiou for their help with developing the treatment protocol and/or leading the therapy sessions. References Sivertsen B, Lallukka T, Salo P, Pallesen S, Hysing M, Krokstad S, Simon O. Insomnia as a risk factor for ill health: results from the large population-based prospective HUNT Study in Norway. J Sleep Res. 2014;23(2):124–32. Zheng B, Yu C, Lv J, Guo Y, Bian Z, Zhou M, et al. Insomnia symptoms and risk of cardiovascular diseases among 0.5 million adults. Neurology. 2019;93(23):e2110–20. Hertenstein E, Feige B, Gmeiner T, Kienzler C, Spiegelhalder K, Johann A, et al. Insomnia as a predictor of mental disorders: A systematic review and meta-analysis. Sleep Med Rev. 2019;43:96–105. Schlarb AA, Claßen M, Grünwald J, Vögele C. Sleep disturbances and mental strain in university students: results from an online survey in Luxembourg and Germany. Int J Mental Health Syst. 2017;11(1). 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Sheehan DV, Lecrubier Y, Sheehan KH, Amorim P, Janavs J, Weiller E et al. The Mini-International Neuropsychiatric Interview (M.I.N.I.): the development and validation of a structured diagnostic psychiatric interview for DSM-IV and ICD-10. J Clin Psychiatry. 1998;59 Suppl 20:22–33;quiz 4–57. Morin CM, Belleville G, Bélanger L, Ivers H. The Insomnia Severity Index: Psychometric Indicators to Detect Insomnia Cases and Evaluate Treatment Response. Sleep. 2011;34(5):601–8. Bastien C. Validation of the Insomnia Severity Index as an outcome measure for insomnia research. Sleep Med. 2001;2(4):297–307. Beck AT, Steer RA, Brown GK. Manual for the beck depression inventory-II. San Antonio, TX: Psychological Corporation. 1996;1(82):10.1037. Zigmond AS, Snaith RP. The hospital anxiety and depression scale. Acta Psychiatr Scand. 1983;67(6):361–70. Endicott J, Nee J, Harrison W, Blumenthal R. Quality of Life Enjoyment and Satisfaction Questionnaire: a new measure. Psychopharmacol Bull. 1993;29(2):321–6. Morin CM, Vallières A, Ivers H. Dysfunctional beliefs and attitudes about sleep (DBAS): validation of a brief version (DBAS-16). Sleep. 2007;30(11):1547–54. Nicassio PM, Mendlowitz DR, Fussell JJ, Petras L. The phenomenology of the pre-sleep state: The development of the pre-sleep arousal scale. Behav Res Ther. 1985;23(3):263–71. Cohen J. Statistical power analysis for the behavioral sciences. Routledge; 2013. Hayes AF. Introduction to mediation, moderation, and conditional process analysis: A regression-based approach. Guilford; 2017. Freeman D, Sheaves B, Goodwin GM, Yu L-M, Nickless A, Harrison PJ, et al. The effects of improving sleep on mental health (OASIS): a randomised controlled trial with mediation analysis. Lancet Psychiatry. 2017;4(10):749–58. Ong JC, Shapiro SL, Manber R. Combining Mindfulness Meditation with Cognitive-Behavior Therapy for Insomnia: A Treatment-Development Study. Behav Ther. 2008;39(2):171–82. Alimoradi Z, Jafari E, Broström A, Ohayon MM, Lin C-Y, Griffiths MD, et al. Effects of cognitive behavioral therapy for insomnia (CBT-I) on quality of life: A systematic review and meta-analysis. Sleep Med Rev. 2022;64:101646. Gebara MA, Siripong N, DiNapoli EA, Maree RD, Germain A, Reynolds CF, et al. Effect of insomnia treatments on depression: A systematic review and meta-analysis. Depress Anxiety. 2018;35(8):717–31. Lancee J, Effting M, Van Der Zweerde T, Van Daal L, Van Straten A, Kamphuis JH. Cognitive processes mediate the effects of insomnia treatment: evidence from a randomized wait-list controlled trial. Sleep Med. 2019;54:86–93. Chow PI, Ingersoll KS, Thorndike FP, Lord HR, Gonder-Frederick L, Morin CM, Ritterband LM. Cognitive mechanisms of sleep outcomes in a randomized clinical trial of internet-based cognitive behavioral therapy for insomnia. Sleep Med. 2018;47:77–85. Harvey AG, Dong L, Bélanger L, Morin CM. Mediators and treatment matching in behavior therapy, cognitive therapy and cognitive behavior therapy for chronic insomnia. J Consult Clin Psychol. 2017;85(10):975–87. Parsons CE, Zachariae R, Landberger C, Young KS. How does cognitive behavioural therapy for insomnia work? A systematic review and meta-analysis of mediators of change. Clin Psychol Rev. 2021;86:102027. Norell-Clarke A, Tillfors M, Jansson-Fröjmark M, Holländare F, Engström I. How Does Cognitive Behavioral Therapy for Insomnia Work? An Investigation of Cognitive Processes and Time in Bed as Outcomes and Mediators in a Sample With Insomnia and Depressive Symptomatology. Int J Cogn Therapy. 2017;10(4):304–29. Blanken TF, Van Der Zweerde T, Van Straten A, Van Someren EJW, Borsboom D, Lancee J. Introducing Network Intervention Analysis to Investigate Sequential, Symptom-Specific Treatment Effects: A Demonstration in Co-Occurring Insomnia and Depression. Psychother Psychosom. 2019;88(1):52–4. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 05 Nov, 2024 Read the published version in BMC Psychology → Version 1 posted Editorial decision: Revision requested 03 Jul, 2024 Editor assigned by journal 02 Jul, 2024 Submission checks completed at journal 02 Jul, 2024 First submitted to journal 21 Jun, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4617700","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":322140290,"identity":"498ac58c-891b-480e-92c5-48ec4d1068ea","order_by":0,"name":"Laura M. 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Kivelä","email":"","orcid":"","institution":"Leiden University","correspondingAuthor":false,"prefix":"","firstName":"Liia","middleName":"M.M.","lastName":"Kivelä","suffix":""},{"id":322140295,"identity":"e23bb1c2-7d75-45f7-9a54-deeef887f517","order_by":3,"name":"Annemieke van Straten","email":"","orcid":"","institution":"VU Amsterdam","correspondingAuthor":false,"prefix":"","firstName":"Annemieke","middleName":"van","lastName":"Straten","suffix":""},{"id":322140296,"identity":"b20860e5-a5ed-4da7-bf84-9eea843c3dc1","order_by":4,"name":"Niki Antypa","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABCUlEQVRIiWNgGAWjYBADOfYGIPmAQYIRRDMkADEfbtVgRcY8B8AqkbSwEdCS2APRAuGBAS4t5uxnjz/m3WGX3sN/xoAhocJCtl+6x+zBwzaGPFxaLHvyEpt5zyTn9kjkALWckTCeOeeMuUFiG0MxLi0GB3IMm3nbmHP3S/BuYEhsk0jccCPHTCLhDJCNS8v5NyAt9ek8/GeBWv5JJO4nqOUG2JbDCTwMuUAtDUBbJEBaKvBpeWM4c+6Z44Y9EvkfDiQckzCecSOtDKhFAo/Dcgw+vN1RLc/DfyzxwYeaOtn+GcnbJH8Y2CT249ACAky8DRDGASRBCTwagLH3swGv/CgYBaNgFIx0AACXplvDaGyIwQAAAABJRU5ErkJggg==","orcid":"","institution":"Leiden University","correspondingAuthor":true,"prefix":"","firstName":"Niki","middleName":"","lastName":"Antypa","suffix":""}],"badges":[],"createdAt":"2024-06-21 13:26:59","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4617700/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4617700/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s40359-024-02057-1","type":"published","date":"2024-11-05T15:57:19+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":61181531,"identity":"c51b3cf9-1d31-4dd8-905a-840ff18359a9","added_by":"auto","created_at":"2024-07-26 16:50:21","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":844334,"visible":true,"origin":"","legend":"\u003cp\u003eOverview of the study design - CONSORT flow diagram\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eNote\u003c/em\u003e. Flow diagram of participants in the study. ISI = Insomnia Severity Index; HADS-A = Hospital Anxiety and Depression Scale – Subscale Anxiety; BDI II = Beck Depression Inventory II; Q-LES-Q-sf = Quality of Life Enjoyment and Satisfaction Questionnaire; DBAS = Dysfunctional Beliefs and Attitudes about Sleep Scale; PSAS = Pre-Sleep Arousal Scale.\u003c/p\u003e","description":"","filename":"Figure1OverviewoftheStudyDesignConsortflowdiagram.png","url":"https://assets-eu.researchsquare.com/files/rs-4617700/v1/1a24e2c232096d11471a1536.png"},{"id":61181530,"identity":"05cce8c1-2060-4f74-b53c-11bfda19084c","added_by":"auto","created_at":"2024-07-26 16:50:21","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":261265,"visible":true,"origin":"","legend":"\u003cp\u003eInteraction plots for pre- and post-test means for SMILE and waitlist\u003c/p\u003e\n\u003cp\u003eNote: Means of Insomnia Severity (ISI), Depressive Symptoms (BDI-II), Anxiety Symptoms (HADS-A), and Quality of Life (Q-LES-Q) in SMILE and waitlist group at pre-test and post-test. Error bars represent standard error of the mean. * Significant mean difference p\u0026lt; .05.\u003c/p\u003e","description":"","filename":"Figure2Interactionplots.png","url":"https://assets-eu.researchsquare.com/files/rs-4617700/v1/85902674f4a5f4b54b46fe1f.png"},{"id":68750194,"identity":"bbd4eae0-e6bc-47ec-9d21-a580a26c779e","added_by":"auto","created_at":"2024-11-11 16:11:33","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1734115,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4617700/v1/6cbe3516-0ff4-47b2-ad57-a39889d0987e.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Effectiveness of a Multi-component Sleep-Mood Group Intervention on Improving Insomnia in University Students – a Pilot Randomized Controlled Trial","fulltext":[{"header":"1. Background","content":"\u003cp\u003eInsomnia is a major public health problem and can, if untreated, lead to a range of physical and mental health problems, such as hypertension, obesity, cardiovascular disease, depression and anxiety disorders (\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e). Sleep problems are especially common among university students (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e). A systematic review of the prevalence of insomnia in 16,748 university students found a weighted mean of 18.5% (ranging from 9.4\u0026ndash;38.2%), which was substantially higher than in the general population at 7.4% (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe increased prevalence of insomnia may be attributed to numerous challenges in the lives of students. University students face high expectations of their education and future careers, have to develop greater personal independence, and face the challenge of balancing social activities, part-time jobs, and self-directed studying, all while contending with financial pressure due to rising tuition fees and living expenses (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e). These generally conflicting demands can lead to excess stress among students, making them a high-risk population for both sleep disturbances and mental health complaints (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e). Moreover, university students are in an age group that is particularly vulnerable to the onset of psychopathology (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eA growing body of literature supports the effectiveness of psychological interventions for insomnia, especially cognitive behavioral therapy for insomnia (CBT-I). During CBT-I, patients learn to identify and modify maladaptive thoughts, attitudes, and behaviors, by utilizing psychoeducation, cognitive restructuring, stimulus control, sleep restriction, and relaxation techniques. It has been shown effective in both individual and group face-to-face formats as well as in online formats (\u003cspan additionalcitationids=\"CR11\" citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e), and even for those with subthreshold insomnia (\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e). About 70\u0026ndash;80% of people with insomnia benefit from CBT-I (\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e). Furthermore, sleep interventions including CBT-I show smaller effect sizes in students than in the general adult population (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e). Chandler et al. almost exclusively included CBT-I studies and found a moderate effect size (\u003cem\u003ed\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.55), while Saruhanjan et al. and Kodsi et al. included more studies with different types of sleep interventions, such as sleep education and relaxation training, and found moderate effects on sleep, with effect estimates of 0.61 and 0.51, respectively. A possible explanation for the smaller effect size in students may be that several interrelated factors are especially relevant in the lives of students that are insufficiently addressed in current interventions. For instance, issues relevant to students include perfectionism, stress-sleep reactivity, poor psychological flexibility and coping skills, which are known to contribute to the development and maintenance of sleep problems (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan additionalcitationids=\"CR18\" citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e) and may have to be emphasized more in a student population. Students may require a tailored approach that considers their specific challenges and circumstances. Interventions targeting multiple behaviors and skills simultaneously may therefore be more effective than single-component treatments to promote better sleep among students.\u003c/p\u003e \u003cp\u003eA promising add-on to CBT-I is mindfulness-based interventions. Mindfulness is a practice aiming to direct an individual\u0026rsquo;s attention to the present moment without judgement and increase awareness of internal and external experiences (\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e). It is used to decrease stress and increase mental well-being through exercises such as breath regulation and body-scan meditation (\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e). A recent meta-analysis of seven RCT\u0026rsquo;s showed that mindfulness-based stress reduction significantly improved sleep quality, depression, and anxiety among adult insomnia patients (\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e). Another study among adolescent girls examined the effectiveness of a multi-component mindfulness-based group intervention and found that the intervention was feasible and resulted in moderate improvements in subjective sleep (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e). Therefore, in order to tackle the stress-related factors mentioned above that are intertwined with the lives of students, mindfulness-based techniques might be a fruitful add-on to sleep interventions.\u003c/p\u003e \u003cp\u003eA brief group multi-component sleep-mood intervention combining CBT-I and mindfulness practices with lifestyle components, the Sleep Mood Intervention: Live Effectively (SMILE) intervention, was developed to target sleep and mood in university students, taking into account the needs of this target group. The objective of the present study was to assess the effectiveness of the SMILE intervention in university students with sleep complaints. The primary outcome was insomnia severity. The secondary outcomes were symptoms of depression, anxiety and quality of life. Given the close relationship between sleep and mental health, we hypothesized that SMILE improves all outcomes. Secondly, we explored the mechanisms of change, namely whether the treatment effect on insomnia was mediated by dysfunctional beliefs about sleep and levels of pre-sleep arousal. Both are factors that have been previously assessed as mediators in other intervention studies on sleep outcomes (\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e).\u003c/p\u003e"},{"header":"2. Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Study Design\u003c/h2\u003e \u003cp\u003eThe current research is a pilot randomized controlled trial to determine the effectiveness of a multi-component sleep-mood intervention (the SMILE intervention; Sleep Mood Intervention: Live Effectively) in university students on reduction of insomnia symptoms comparing two groups: the SMILE intervention group and a waiting list control group with an allocation ratio of 2:1. The study included a baseline period of one week, an intervention period of four weeks, and a post-intervention period of one week. Participants in the wait-list condition received the SMILE intervention after six weeks. The study was approved by the Medical Ethical Committee Leiden The Hague Delft (METC-LDD) in the Netherlands (NL64330.058.17, September 18th, 2018) and was registered at the Overzicht van Medisch-wetenschappelijk Onderzoek register (registration number: NL-OMON46359) on September 18th, 2018. This study was carried out in accordance with the Declaration of Helsinki and the guidelines of Good Clinical Practice (GCP).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Recruitment and Participant Screening\u003c/h2\u003e \u003cp\u003eParticipants were recruited between September 19th, 2018 and February 11th, 2020. Recruitment took place at Leiden University through posters placed in university buildings, on social media via postings in student groups, as well as through referrals from other studies. The recruitment process consisted of two stages. First, pre-screening of participants was performed through online questionnaires, including the Insomnia Severity Index (ISI) with a cut-off of \u0026ge;\u0026thinsp;10, to identify students with current sleep problems. Second, all participants deemed eligible through the pre-screening procedure and willing to participate in the study completed a face-to-face diagnostic interview with the M.I.N.I Plus International Neuropsychiatric Interview (\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e) confirming that the participants met the full inclusion and exclusion criteria.\u003c/p\u003e \u003cp\u003eInclusion criteria were 1) self-reported sleep complaints with ISI score of \u0026ge;\u0026thinsp;10, representing clinically significant insomnia (\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e); 2) being enrolled as a university student 3) being 18 years or older; 4) adequate proficiency in both written and spoken English; and 5) willingness to participate in a four-week group intervention program and giving informed consent. Students were excluded under the following circumstances: 1) in the presence of clinically significant psychopathology (as based on DSM-IV criteria from the M.I.N.I. diagnostic interview) regarding: current Major Depressive Disorder, Bipolar Disorder, Panic disorder, Social Anxiety Disorder, Post-traumatic Stress Disorder, Attention Deficit Hyperactivity Disorder, Eating disorders, and Psychotic disorders; 2) in the presence of a sleep disorder such as narcolepsy or sleep apnea; 3) in the presence of acute somatic illness that might interfere with the intervention; 4) currently (past month) using medication known to influence sleep (e.g. hypnotics, anxiolytics, antidepressants, stimulants, and \u0026gt;\u0026thinsp;0.5mg melatonin per day), except for antidepressant treatment which if it was started more than 3 months prior to study enrollment and dosage was stable then the participant was included; 5) current substance use dependency; and 6) concurrent psychotherapy (e.g. CBT, including past CBT for sleep or depression).\u003c/p\u003e \u003cp\u003eAn overview of the study design can be found in Fig.\u0026nbsp;1. The online eligibility screening was completed by 91 students, of which 19 were excluded due to scoring\u0026thinsp;\u0026lt;\u0026thinsp;10 on the ISI. Sixty-six students were invited to the intake and completed the psychiatric interview. After this intake, 31 students were excluded due to exclusion criteria during or after the initial screening. Thirty-five people were randomized into SMILE (n\u0026thinsp;=\u0026thinsp;23) or waitlist group (n\u0026thinsp;=\u0026thinsp;12). Randomization took place by an independent researcher with a 2 : 1 ratio for intervention : waiting list, respectively. This was done for clinical purposes, in order to provide help to more students. Groups could start when enough participants had been enrolled to form groups, this took on average 4\u0026ndash;6 weeks to achieve.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Intervention\u003c/h2\u003e \u003cp\u003eThe SMILE intervention (Sleep Mood Intervention: Live Effectively) is a group therapy intervention with a duration of four weeks (two-hour sessions weekly). Each session covers different topics: Session 1) Sleep education, sleep hygiene, stimulus control, and sleep restriction; Session 2) negative thoughts; Session 3) relaxation techniques and mindfulness; Session 4) lifestyle issues. Further information on the content of the SMILE intervention can be found in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Therapists were trained Master-level psychologists. They were instructed to follow the intervention protocol; for the fourth session (lifestyle issues), a range of issues was covered taking into account the needs of each group. Each group had a maximum of six participants.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003e\u003cem\u003eContent of the SMILE intervention\u003c/em\u003e\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSession\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eContent\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSession 1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eIntroduction \u0026ndash; Sleep education and hygiene\u003c/b\u003e\u003c/p\u003e \u003cp\u003e- Biology of sleep, effects of sleep deprivation, importance of sleep in physical and mental wellbeing\u003c/p\u003e \u003cp\u003e- Sleep hygiene (behaviours that promote healthy sleep), e.g. sleep schedule, avoiding daytime napping, and limiting coffee and substance use\u003c/p\u003e \u003cp\u003e- Stimulus control (strengthen the bed as a cue for sleep)\u003c/p\u003e \u003cp\u003e- Sleep restriction (limiting the hours in bed)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c3\" namest=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSession 2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e\u003cb\u003eThe Mind \u0026ndash; Dealing with negative thoughts\u003c/b\u003e\u003c/p\u003e \u003cp\u003e- Concept of cognitive arousal and its impact on sleep\u003c/p\u003e \u003cp\u003e- Cognitive behavioural techniques\u003c/p\u003e \u003cp\u003e- Dysfunctional thoughts about sleep or non-sleep related\u003c/p\u003e \u003cp\u003e- Constructive worrying and positive refocusing\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSession 3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e\u003cb\u003eThe Body \u0026ndash; Relaxation and Mindfulness\u003c/b\u003e\u003c/p\u003e \u003cp\u003e- Dealing with stress and arousal\u003c/p\u003e \u003cp\u003e- Deep (diaphragmatic) breathing\u003c/p\u003e \u003cp\u003e- Progressive muscle relaxation\u003c/p\u003e \u003cp\u003e- Mindfulness practice directed at challenging automatic reactions to stress, increasing awareness to the present moment, and letting go of negative thoughts associated with sleep\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSession 4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e\u003cb\u003eThe Whole \u0026ndash; Lifestyle Issues\u003c/b\u003e\u003c/p\u003e \u003cp\u003e- Cognitive and behavioural patterns influencing sleep\u003c/p\u003e \u003cp\u003e- Substance use (alcohol, drugs, smoking)\u003c/p\u003e \u003cp\u003e- Lifestyle topics such as flexibility and planning, perfectionism, burnout, diet, self-acceptance\u003c/p\u003e \u003cp\u003e- Summary and relapse prevention plan\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.4 Measurements\u003c/h2\u003e \u003cp\u003e \u003cem\u003eAssessment Points\u003c/em\u003e \u003c/p\u003e \u003cp\u003eAssessments took place at baseline (T0) and after five weeks (T1). After T1, all participants in the waitlist control group were offered the SMILE intervention, which finished the controlled element of the trial. Demographic characteristics were assessed at baseline.\u003c/p\u003e \u003cp\u003e \u003cem\u003ePrimary Outcome\u003c/em\u003e \u003c/p\u003e \u003cp\u003eInsomnia complaints were measured with the 7-item ISI (\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e). A higher score suggests more insomnia severity in the past week or past two weeks, with total scores ranging from 0 (no insomnia) to 28 (severe insomnia). A cut-off score of 10 was determined as optimal to indicate clinical levels of insomnia and was therefore used as a cut-off for inclusion of participants (\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e). The ISI is a widely used measure with adequate internal consistency and reliability (\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e). The internal consistency in this sample at baseline was moderate at Cronbach\u0026rsquo;s α\u0026thinsp;=\u0026thinsp;.65.\u003c/p\u003e \u003cp\u003e \u003cem\u003eSecondary Outcomes\u003c/em\u003e \u003c/p\u003e \u003cp\u003eThe Beck Depression Inventory II is a 21-item questionnaire which measures depressive symptoms in the preceding two weeks. Total scores are ranging from 0 (no depression) to 63 (severe depression). This inventory is shown to be a sensitive and reliable measure (\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e). The internal consistency in this sample was good at Cronbach\u0026rsquo;s α\u0026thinsp;=\u0026thinsp;.84.\u003c/p\u003e \u003cp\u003eAnxiety symptoms were assessed using the anxiety subscale of the Hospital Anxiety and Depression Scale (HADS-A) (\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e). Seven items are assessed to measure anxiety over the past week. The total score ranges from 0 (no symptoms of anxiety) to 21 (severe symptoms of anxiety). Internal consistency of the HADS-A in this sample was moderate, with Cronbach\u0026rsquo;s α\u0026thinsp;=\u0026thinsp;.76.\u003c/p\u003e \u003cp\u003eQuality of life was measured with the Quality of Life Enjoyment and Satisfaction Questionnaire - short form (Q-LES-Q-sf) (\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e). The Q-LES-Q contains 16 item-domains, including physical health, mood, work, social relations, ability to function in daily life and more. Totals scores range from 14 to 70, with higher scores indicating better quality of life. The internal consistency in our sample was satisfactory at α\u0026thinsp;=\u0026thinsp;.78.\u003c/p\u003e \u003cp\u003e \u003cem\u003eOther Outcomes\u003c/em\u003e \u003c/p\u003e \u003cp\u003eDysfunctional Beliefs and Attitudes of Sleep (DBAS-16) were assessed as a mediator variable. The DBAS consists of 16 items evaluating beliefs, expectations, and attitudes about sleep complaints (\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e). Each item statement is rated on a scale from 0 (strongly disagree) to 10 (strongly agree), and higher scores indicate more dysfunctional beliefs and attitudes. The questionnaire is found to have adequate psychometric properties (\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e). The internal consistency in our sample was satisfactory at Cronbach\u0026rsquo;s α\u0026thinsp;=\u0026thinsp;.77.\u003c/p\u003e \u003cp\u003eSleep-related arousal was measured with the Pre-Sleep Arousal Scale (PSAS), which measures subjective arousal before sleep in 16 items (\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e). The questionnaire measures two subscales: cognitive arousal and somatic arousal. We reported the sum score of the PSAS (ranging from 8 to 40). Higher scores indicate more pre-sleep arousal. The internal consistency was good with Cronbach\u0026rsquo;s α\u0026thinsp;=\u0026thinsp;.87.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e2.5 Deviations from the Study Protocol\u003c/h2\u003e \u003cp\u003eA total sample size of 72 participants was required to have sufficient power (0.80) to be able to detect differences of a small effect size (\u003cem\u003ed\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.17) using alpha\u0026thinsp;\u0026lt;\u0026thinsp;0.05 and repeated measures ANOVA. This was calculated using the G*Power v3.1.9.2. tool. However, there was a premature termination of the study due to the COVID-19 pandemic. Organization of the group session in an online format was not possible, not only due to a lack of resources, but also as it would have resulted in fundamental changes to the intervention content. After the COVID-19 break out (March 2020), the recruitment stopped. Furthermore, in the study protocol, subjective sleep quality assessed with a sleep diary was listed as another primary outcome measure. However, due to large amounts of missing data (14 participants (40%) had sufficient data at both pre-test and post-test) data imputation was not possible and therefore this outcome was not analyzed and not reported.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e2.6 Statistical Analysis\u003c/h2\u003e \u003cp\u003eAll analyses were performed as intention to treat in IBM SPSS Statistics (version 27.0). Analyses were carried out using a 0.05 α-level (two-tailed). Baseline differences between the two groups were tested with independent samples, t-tests for continuous variables, and chi-square tests for categorical variables. Data was checked for outliers and for assumptions for parametric analyses. Last observation carried forward was used to impute missing values at post-test (n\u0026thinsp;=\u0026thinsp;2).\u003c/p\u003e \u003cp\u003eThe primary and secondary outcomes were analyzed using a repeated measures analysis of variance (ANOVA), with condition (SMILE versus waitlist) as between-subjects factor, and time (T0 versus T1) as within-subjects factor. The magnitude of the effect for the within-group change and difference between groups at post-test was calculated using Cohen\u0026rsquo;s d, with 0.2, 0.5 and 0.8 as small, moderate and large effects, respectively (\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e). Participants were categorized as a remitter when the ISI score at post-test was below 10 points, and participants were categorized as treatment responders when there was a reduction in the total ISI score of \u0026ge;\u0026thinsp;8 points (\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFor mediation analysis of DBAS and PSAS, Hayes\u0026rsquo; \u0026lsquo;PROCESS\u0026rsquo; tool (model 4) was used with 10.000 bootstrap re-samples (\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e). Group allocation was the independent variable, insomnia severity the dependent variable, and DBAS and PSAS the mediator variables, in two separate models. We used the pre- to post-test change scores of the ISI to correct for baseline values. Mediation was tested using the 95% confidence interval of the indirect effect (\u003cem\u003epath ab\u003c/em\u003e).\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results","content":"\u003cp\u003eParticipant\u0026rsquo;s demographic characteristics can be found in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. The mean age of the sample was 22.8 (SD\u0026thinsp;=\u0026thinsp;4.2) and 74.3% of the participants were female. There were no significant differences between the groups at baseline (all \u003cem\u003ep\u003c/em\u003e\u0026rsquo;s\u0026thinsp;\u0026gt;\u0026thinsp;0.05). Even though none of the differences were statistically significant, the intervention group had a higher proportion of female participants (82.6%), higher proportion of international students (65.2%), and higher proportion of students consuming alcohol (78.3%) compared to the control group. The study compliance was very high, as 94% of all students completed T1. Compliance with the sessions in the intervention group was also high, since almost all students in the intervention group (n\u0026thinsp;=\u0026thinsp;21, 95.5%) attended all four sessions, and one student attended the first three sessions. Two students (5.7%, N\u0026thinsp;=\u0026thinsp;35) dropped out of the study, one in each group (one due to the death of a family member and one due to unknown reasons).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003e\u003cem\u003eDemographic characteristics of the study sample (n\u0026thinsp;=\u0026thinsp;35)\u003c/em\u003e\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSMILE\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eWaitlist\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eCharacteristic\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003en\u0026thinsp;=\u0026thinsp;23\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003en\u0026thinsp;=\u0026thinsp;12\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eAge, mean (SD), years\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e23.5 (4.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e21.4 (1.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003et\u003c/em\u003e(\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e) = -1.44, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;.06\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eGender, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFemale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e19 (82.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7 (58.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4 (17.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5 (41.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eΧ\u0026sup2;\u003c/em\u003e (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e)\u0026thinsp;=\u0026thinsp;2.43, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;.12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c5\" namest=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eNationality, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDutch\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8 (34.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7 (58.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOther\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e15 (65.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5 (41.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eΧ\u0026sup2;\u003c/em\u003e (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e)\u0026thinsp;=\u0026thinsp;1.79, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;.28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c5\" namest=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eRelationship status, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eIn a relationship\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6 (26.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5 (41.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMarried or cohabitating\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2 (8.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c5\" namest=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSingle\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e15 (65.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7 (58.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eΧ\u0026sup2;\u003c/em\u003e (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e)\u0026thinsp;=\u0026thinsp;1.71, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;.43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c5\" namest=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eMedication, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNo medication\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e19 (82.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e11 (91.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAntidepressants\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1 (4.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c5\" namest=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNon-psychoactive medication\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1 (4.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1 (8.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c5\" namest=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIron supplements\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2 (8.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eΧ\u0026sup2;\u003c/em\u003e (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e)\u0026thinsp;=\u0026thinsp;1.86, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;.60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c5\" namest=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eAlcohol use, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e18 (78.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7 (58.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eΧ\u0026sup2;\u003c/em\u003e (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e)\u0026thinsp;=\u0026thinsp;.22, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;.26\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5 (21.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5 (41.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c5\" namest=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eInsomnia Severity (ISI), mean (SD)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e14.3 (3.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e15.7 (5.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003et\u003c/em\u003e(\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e)\u0026thinsp;=\u0026thinsp;0.98, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;.12\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eDepressive symptoms (BDI II), mean (SD)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e11.9 (7.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e11.5 (6.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003et\u003c/em\u003e(\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e) = -0.15, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;.67\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eAnxiety symptoms (HADS-A), mean (SD)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8.9 (3.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e8.8 (4.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003et\u003c/em\u003e(\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e) = -0.06, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;.50\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eQuality of Life (Q-LES-Q), mean (SD)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e54.7 (13.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e61.2 (10.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003et\u003c/em\u003e(\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e)\u0026thinsp;=\u0026thinsp;1.45, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;.37\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003ePre-Sleep Arousal (PSAS), mean (SD)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e42.6 (8.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e42.1 (10.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003et\u003c/em\u003e(\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e) = -0.16, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;.41\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eDysfunctional Beliefs and Attitudes about\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e73.2 (19.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e78.4 (20.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003et\u003c/em\u003e(\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e) = -0.47, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;.97\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eSleep (DBAS), mean (SD)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003e\u003cem\u003eNote.\u003c/em\u003e Non-psychoactive medication: Ibuprofen n\u0026thinsp;=\u0026thinsp;1; Antibiotics n\u0026thinsp;=\u0026thinsp;1.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Treatment Effects on Insomnia Severity\u003c/h2\u003e \u003cp\u003eRepeated measures ANOVA was conducted to test whether the SMILE intervention was effective in reducing insomnia severity compared to a control group in an intention-to-treat analysis (n\u0026thinsp;=\u0026thinsp;35). There was a significant time x treatment effect \u003cem\u003eF\u003c/em\u003e(\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e)\u0026thinsp;=\u0026thinsp;5.91, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;.021, \u003cem\u003eη2\u003c/em\u003e\u0026thinsp;=\u0026thinsp;.152, in the unadjusted model. The main effect of time was significant \u003cem\u003eF\u003c/em\u003e(\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e)\u0026thinsp;=\u0026thinsp;18.46, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;.001, \u003cem\u003eη2\u003c/em\u003e\u0026thinsp;=\u0026thinsp;.359. The main effect of group allocation was non-significant \u003cem\u003eF\u003c/em\u003e(\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e)\u0026thinsp;=\u0026thinsp;3.31, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;.078, \u003cem\u003eη2\u003c/em\u003e\u0026thinsp;=\u0026thinsp;.091. Sensitivity analysis with complete cases showed similar results, with a significant interaction effect of \u003cem\u003eF\u003c/em\u003e(\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e)\u0026thinsp;=\u0026thinsp;5.74, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;.023, \u003cem\u003eη2\u003c/em\u003e\u0026thinsp;=\u0026thinsp;.156. Those who received the SMILE intervention had significantly lower insomnia severity (M\u0026thinsp;=\u0026thinsp;10.7, SD\u0026thinsp;=\u0026thinsp;4.8) compared to the waitlist at post-test (M\u0026thinsp;=\u0026thinsp;14.7, SD\u0026thinsp;=\u0026thinsp;4.9), \u003cem\u003et\u003c/em\u003e(\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e)\u0026thinsp;=\u0026thinsp;2.33; \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;.026, 95% CI [.51 to 7.52], representing a large effect with Cohen\u0026rsquo;s \u003cem\u003ed\u003c/em\u003e\u0026thinsp;=\u0026thinsp;.83, 95% CI [.098 to 1.55].\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Clinically Significant Improvement of Insomnia\u003c/h2\u003e \u003cp\u003eIn the SMILE group, 47.8% of the students were treatment remitters with a post-test insomnia severity score of less than 10, compared to 16.7% in the waitlist group [\u003cem\u003eX\u003c/em\u003e\u003csup\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e (1, \u003cem\u003eN\u003c/em\u003e\u0026thinsp;=\u0026thinsp;35)\u0026thinsp;=\u0026thinsp;3.28, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;.07]. In the SMILE group, 9.4% of students (n\u0026thinsp;=\u0026thinsp;3) were treatment responders with a reduction in total ISI score of \u0026ge;\u0026thinsp;8 points, compared to no responders in the waitlist group[\u003cem\u003eX\u003c/em\u003e\u003csup\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e)\u0026thinsp;=\u0026thinsp;1.5, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;.22].\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003e3.3 Treatment Effects on Secondary Mental Health Outcomes\u003c/h2\u003e \u003cp\u003eResults of repeated measures ANOVA indicated that the differences in anxiety symptoms between SMILE and waitlist group from T0 to T1 were non-significant \u003cem\u003eF\u003c/em\u003e(\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e)\u0026thinsp;=\u0026thinsp;2.21, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;.147, \u003cem\u003eη2\u003c/em\u003e\u0026thinsp;=\u0026thinsp;.063. Post-test differences were non-significant as well with \u003cem\u003et\u003c/em\u003e(\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e)\u0026thinsp;=\u0026thinsp;.803, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;.428, and a Cohen\u0026rsquo;s \u003cem\u003ed\u003c/em\u003e\u0026thinsp;=\u0026thinsp;.29, 95% CI [-.42 to .99]. For depressive symptoms, repeated measures ANOVA with square root transformed data showed that there was no significant interaction effect for depression either, \u003cem\u003eF\u003c/em\u003e(\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e)\u0026thinsp;=\u0026thinsp;2.95, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;.095, \u003cem\u003eη2\u003c/em\u003e\u0026thinsp;=\u0026thinsp;.082. Mann-Whitney U test on the skewed BDI scores revealed no significant differences between SMILE and waitlist condition at post-test, \u003cem\u003eU\u003c/em\u003e\u0026thinsp;=\u0026thinsp;101.5, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;.204. Results of repeated measures ANOVA on quality of life furthermore revealed no interaction effect on quality of life, \u003cem\u003eF\u003c/em\u003e(\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e)\u0026thinsp;=\u0026thinsp;2.29, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;.139, \u003cem\u003eη2\u003c/em\u003e\u0026thinsp;=\u0026thinsp;.065. Post-test differences between the two groups were also not significant \u003cem\u003et\u003c/em\u003e(\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e)\u0026thinsp;=\u0026thinsp;\u0026minus;\u0026thinsp;.349, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;.71, with Cohen\u0026rsquo;s \u003cem\u003ed\u003c/em\u003e\u0026thinsp;=\u0026thinsp;\u0026minus;\u0026thinsp;.124, 95% CI [-.82 to .56]. Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e presents the results for primary and secondary outcomes. Figure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e2\u003c/span\u003e shows the interaction plots for pre- and post-test means of the main outcomes.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003e\u003cem\u003ePrimary and secondary outcomes by treatment groups\u003c/em\u003e\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"14\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c13\" colnum=\"13\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c14\" colnum=\"14\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003eSMILE (n\u0026thinsp;=\u0026thinsp;23)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c8\" namest=\"c6\"\u003e \u003cp\u003eWaitlist (n\u0026thinsp;=\u0026thinsp;12)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c11\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c13\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c14\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePre-test\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePost-test\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eCohen's d T0-T1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003ePre-test\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003ePost-test\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eCohen\u0026rsquo;s d\u003c/p\u003e \u003cp\u003eT0-T1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c11\" namest=\"c10\"\u003e \u003cp\u003e\u003cem\u003eTime\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c14\" namest=\"c12\"\u003e \u003cp\u003e\u003cem\u003eGroup x Time\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePrimary outcomes\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMean (SD)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMean (SD)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ePre-Post\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eMean (SD)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eMean (SD)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003ePre-Post\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e\u003cem\u003ep\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e\u003cem\u003ep\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c14\"\u003e \u003cp\u003e\u003cem\u003eη2\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eInsomnia Severity (ISI)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e14.3 (3.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e10.7 (4.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e15.7 (5.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e14.7 (4.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e18.46\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e5.91\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e\u003cb\u003e.021*\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c14\"\u003e \u003cp\u003e.152\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSecondary outcomes\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c14\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAnxiety symptoms (HADS-A)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e8.9 (3.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8.2 (3.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e8.8 (4.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e9.3 (4.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e.17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e.681\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e2.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e.681\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c14\"\u003e \u003cp\u003e.005\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDepressive symptoms (BDI II)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e11.9 (7.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e11.0 (8.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e11.5 (6.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e12.8 (5.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e.003\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e.958\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e2.95\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e.095\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c14\"\u003e \u003cp\u003e.082\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eQuality of life (Q-LES-Q)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e54.7 (12.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e56.1 (17.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e61.2 (10.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e54.0 (15.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e.992\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e.327\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e2.29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e.139\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c14\"\u003e \u003cp\u003e.065\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePre-Sleep Arousal (PSAS)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e42.5 (9.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e35.7 (10.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.71\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e43.5 (10.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e43.1 (10.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e3.76\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e.062\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e3.76\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e.062\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c14\"\u003e \u003cp\u003e.089\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDysfunctional Beliefs and Attitudes about Sleep ( DBAS)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e81.8 (19.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e67.9 (13.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.82\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e78.4 (20.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e79.8 (19.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.07\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e4.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e.053\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e6.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e\u003cb\u003e.018*\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c14\"\u003e \u003cp\u003e.167\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e* \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c14\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e\u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003e3.4 Mediation Analysis\u003c/h2\u003e \u003cp\u003eThe mediation analysis included group allocation as the independent variable and insomnia severity as the dependent variable. The pre-to-post change scores of DBAS and PSAS were included as mediator variables in two separate models. For intention-to-treat analysis, the total effect (\u003cem\u003epath c\u003c/em\u003e) of group allocation on insomnia severity was significant with \u003cem\u003eb\u003c/em\u003e= -2.61, 95% CI [-4.79 to -0.43].\u003c/p\u003e \u003cp\u003eAs shown in Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, the effect of the SMILE intervention on insomnia severity was mediated by dysfunctional beliefs with \u003cem\u003eb\u003c/em\u003e\u0026thinsp;=\u0026thinsp;1.12, 95% CI [-2.58 to \u0026minus;\u0026thinsp;.06], meaning a decline in dysfunctional beliefs was related to a decline in insomnia severity. 54.7% of the variance was explained by the mediator DBAS. Pre-sleep arousal did not significantly mediate the effect of the SMILE intervention on insomnia severity with \u003cem\u003eb\u003c/em\u003e\u0026thinsp;=\u0026thinsp;\u0026minus;\u0026thinsp;.68, 95% CI [-2.12 to .03]. 50.9% of the variance was explained by the mediator PSAS. Mediation analysis for completers showed the same pattern as for intention to treat.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eDysfunctional beliefs and attitudes and pre-sleep arousal as mediators of the intervention effect on insomnia severity\u003c/p\u003e\u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eM\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDV\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eEffect of independent variable on mediator (\u003cem\u003ea\u003c/em\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eEffect of mediator on dependent variable (\u003cem\u003eb\u003c/em\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eIndirect effect (\u003cem\u003eab\u003c/em\u003e), \u003c/p\u003e \u003cp\u003e[95% CI]\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eDirect effect (\u003cem\u003ec'\u003c/em\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eTotal effect (\u003cem\u003ec\u003c/em\u003e)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDBAS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eISI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eb\u0026thinsp;=\u0026thinsp;15.33, t= \u003c/p\u003e \u003cp\u003e-2.51, SE\u0026thinsp;=\u0026thinsp;6.10 \u003cb\u003e*\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eb\u0026thinsp;=\u0026thinsp;.07, t\u0026thinsp;=\u0026thinsp;2.59, SE\u0026thinsp;=\u0026thinsp;0.28 \u003cb\u003e*\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eb= -1.12,\u003c/p\u003e \u003cp\u003e[-2.58; -0.06] \u003cb\u003e*\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eb= -1.49,\u003c/p\u003e \u003cp\u003et= -1.40, SE\u0026thinsp;=\u0026thinsp;0.65\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eb= -2.61,\u003c/p\u003e \u003cp\u003e[-4.79 to -0.43] *\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePSAS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eISI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eb= -6.14, t= \u003c/p\u003e \u003cp\u003e-1.77, SE\u0026thinsp;=\u0026thinsp;3.47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eb\u0026thinsp;=\u0026thinsp;.11, t\u0026thinsp;=\u0026thinsp;2.15,\u003c/p\u003e \u003cp\u003eSE\u0026thinsp;=\u0026thinsp;0.05\u003cb\u003e*\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eb= -0.68,\u003c/p\u003e \u003cp\u003e[-2.12; 0.03]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eb= -1.93,\u003c/p\u003e \u003cp\u003et= -1.81, SE\u0026thinsp;=\u0026thinsp;1.07\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eb= -2.61,\u003c/p\u003e \u003cp\u003e[-4.79 to -0.43] *\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"7\" nameend=\"c7\" namest=\"c1\"\u003e \u003cp\u003e\u003cem\u003eNote\u003c/em\u003e: M\u0026thinsp;=\u0026thinsp;Mediator variable, DV\u0026thinsp;=\u0026thinsp;Dependent variable, Independent variable\u0026thinsp;=\u0026thinsp;Group allocation, DBAS\u0026thinsp;=\u0026thinsp;Dysfunctional Beliefs and Attitudes about Sleep Scale, PSAS\u0026thinsp;=\u0026thinsp;Pre-Sleep Arousal Scale, ISI\u0026thinsp;=\u0026thinsp;Insomnia Severity Index\u003c/p\u003e \u003cp\u003e* \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;.05\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"4. Discussion","content":"\u003cp\u003eWe found that the SMILE intervention, compared to the waitlist control group, significantly reduced insomnia severity. This finding is in line with previous research in university students, that has shown how the individual components of the SMILE intervention, such as CBT and mindfulness, are beneficial in improving sleep (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e). Recent meta-analyses showed that brief psychological interventions, especially CBT-I, had moderate to large effects in improving sleep outcomes in students (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e), and mindfulness-based stress reduction had moderate effects on sleep quality in insomnia patients (\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e). Also, the combination of both CBT and mindfulness as an integrated intervention in six weekly sessions was associated with improvements in sleep outcomes and a reduction in sleep-related arousal in adults with primary insomnia (\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e). A recent systematic review concluded that multi-component interventions show moderate effects in improving university students' sleep and mental health (\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e). The effect size for insomnia severity in our study was \u003cem\u003eη2\u0026thinsp;=\u003c/em\u003e\u0026thinsp;.152, which corresponds to \u003cem\u003ed\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.84, and was larger than the moderate effect size of \u003cem\u003ed\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.55 reported by Chandler et al. (\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eNo significant effects were found on any of the secondary outcomes. Mental health symptoms either showed a slight positive trend of improvement or remained stable in the intervention group but generally slightly declined in the waitlist group, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e2\u003c/span\u003e. That the improvement in mental health symptoms was not significant is probably a result of low statistical power, but further research needs to verify this in a larger sample. Still, effect sizes for depression and anxiety severity in our study were \u003cem\u003ed\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.60 and \u003cem\u003ed\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.14, respectively. Prior research has shown large improvements in depression and anxiety symptoms after mindfulness-based stress reduction in adults (\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e). Recent systematic reviews and meta-analyses overall have shown that the effects of CBT-I are moderate to large on mood symptoms and moderate on quality of life (\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e). In university students, however, the effects of single-and multi-component sleep interventions were smaller than in adults on the outcomes anxiety with \u003cem\u003eSMD\u003c/em\u003e= -0.23 and depression with \u003cem\u003eSMD\u003c/em\u003e= -0.30 (\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e). Similar to our findings, no improvements in anxiety symptoms were found after a multi-component mindfulness-based group sleep intervention in an adolescent population (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e). These findings show that such sleep interventions might have more specific effects - only on sleep outcomes - in younger populations.\u003c/p\u003e \u003cp\u003eThe mediating effect of the cognitive and arousal processes was examined. Dysfunctional beliefs about sleep significantly mediated the effects of the intervention on insomnia severity. This finding is in line with most previous literature, supporting the evidence of dysfunctional beliefs as a mediator of insomnia symptom improvement following CBT-I (\u003cspan additionalcitationids=\"CR40 CR41 CR42\" citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e). However, the current study design warrants cautious interpretation of the mediation results since we only established a co-occurring change of dysfunctional beliefs and change of insomnia severity. Therefore, although the finding is plausible we emphasize the need for more rigorous mediation research using multiple time points to elucidate the causal mechanisms underlying these associations. Dysfunctional beliefs are an important factor in the treatment of insomnia since it plays a role in increased anxiety around sleep and engagement in sleep-disrupting compensatory behaviors (\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e). Future research might look into the specific beliefs that may change during insomnia treatment, for instance by means of Network Intervention Analysis (\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e). In contrast, pre-sleep arousal did not significantly mediate the effects of the intervention on insomnia severity. In a previous systematic review and meta-analysis, five studies were summarized which included hyperarousal outcomes and they concluded that only limited evidence was found for hyperarousal as a mediator for CBT-I (\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e). It remains challenging to establish causal links between treatment, mechanisms, and outcomes, especially in multi-component interventions such as the SMILE intervention. Still, future studies should consider a range of cognitive factors (e.g., sleep self-efficacy, locus of control) and behavioral factors (e.g., variability in sleep-wake time), as suggested by Schwartz and Carney (\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e), and should utilize rigorous designs with multiple measurements, in order to get a better understanding of how CBT-I works.\u003c/p\u003e \u003cp\u003eThe most important limitation of the study is the small sample size leading to decreased statistical power. Furthermore, as mentioned before, adding a midpoint measurement would have given more information about temporal precedence in the mediation analysis. A final limitation is that the results may not be generalizable to other populations since our sample included a relatively heterogenous group of mostly female students. Nonetheless, the study has some strengths. The study design is a randomized controlled trial and analyses were done with the intention to treat-approach. Furthermore, study drop-out was very low since only two participants (5.7%) dropped out. Adherence to the sessions was high (95.5% attending all sessions), although this is partly attributable to the flexibility of the group leaders, who provided a brief substitute session in case a participant was unable to attend the group session. Still, it is a good indicator of the acceptability of the intervention and feasibility of the current intervention design. The short duration makes this type of multi-component intervention easy to implement in a student population.\u003c/p\u003e"},{"header":"5. Conclusions","content":"\u003cp\u003eIn conclusion, this study has shown that students with insomnia can benefit from a four-week group intervention in improving their insomnia symptoms. Multi-component interventions tailored to the needs of university students offer a promising path in improving sleep problems in this population at risk for both sleep and mental health disturbances. Still, the low number of treatment responders and low effect size in secondary outcomes point towards further investigation. The current treatment might be further examined in a series of case studies in order to deduce what elements need to be added or expanded to make the treatment more effective. Additionally, it would be worthwhile to investigate alternative ways to improve sleep in students. Even though the adherence rate was high in this trial, the recruitment period was long and the recruitment rate was low, indicating that not many students were willing or able to engage in the intervention. A more accessible and scalable alternative to face-to-face group therapy might be internet-delivered interventions. To summarize, future research should include larger samples, multiple measurement moments to formally test mediation, and explore different forms of delivery to further examine the effectiveness of multi-component sleep interventions.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eANOVA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eAnalysis of Variance\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eBDI\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eBeck Depression Inventory\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eCBT-I\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eCognitive Behavioral Therapy for Insomnia\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eDBAS\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eDysfunctional beliefs and attitudes about sleep\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eISI\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eInsomnia Severity Index\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eHADS-A\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eHospital Anxiety and Depression Scale - Subscale Anxiety\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eRCT\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eRandomized controlled trial\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003ePSAS\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003ePre-Sleep Arousal Scale\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eQoL\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eQuality of Life\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eQ-LES-Q\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eQuality of Life Enjoyment and Satisfaction Questionnaire\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003ch2\u003eEthics Approval and consent to participate\u003c/h2\u003e\n\u003cp\u003eEthical approval was attained on September 18th, 2018, from the Medical Ethical Committee Leiden The Hague Delft (METC-LDD) in the Netherlands with reference number NL64330.058.17. All participants in the study gave informed consent. This study was carried out in accordance with the Declaration of Helsinki and the guidelines of Good Clinical Practice (GCP).\u003c/p\u003e\n\u003ch2\u003eConsent for publication\u003c/h2\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003ch2\u003eAvailability of Data and Materials\u003c/h2\u003e\n\u003cp\u003eThe datasets generated and analyzed during the current study are available from the corresponding author on reasonable request and in the DataverseNL repository after study completion.\u003c/p\u003e\n\u003ch2\u003eCompeting interests\u003c/h2\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003ch2\u003eFunding\u003c/h2\u003e\n\u003cp\u003eThe study was supported by funds of the Clinical Psychology Department of Leiden University. The contract of Laura Pape is funded by the Dutch Research Council (NWO) as part of the BioClock Research Project (project number 1292.19.077).\u003c/p\u003e\n\u003ch2\u003eAuthor\u0026rsquo;s Contributions\u003c/h2\u003e\n\u003cp\u003eNA is the principal investigator and wrote the study outline for the grant application. NA and LK developed the treatment protocol, contributed to the study design, carried out the interventions, recruitment, and data collection. SJ and LP performed the statistical analysis. LP drafted the manuscript. NA, LK, and AvS revised the manuscript. All authors approved the final version of the manuscript.\u003c/p\u003e\n\u003ch2\u003eAcknowledgments\u003c/h2\u003e\n\u003cp\u003eThe authors would like to thank Katerina Petsi, Liv Henrich, and Akrivi Kyrgiou for their help with developing the treatment protocol and/or leading the therapy sessions.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eSivertsen B, Lallukka T, Salo P, Pallesen S, Hysing M, Krokstad S, Simon O. Insomnia as a risk factor for ill health: results from the large population-based prospective HUNT Study in Norway. J Sleep Res. 2014;23(2):124\u0026ndash;32.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZheng B, Yu C, Lv J, Guo Y, Bian Z, Zhou M, et al. Insomnia symptoms and risk of cardiovascular diseases among 0.5 million adults. 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Introduction to mediation, moderation, and conditional process analysis: A regression-based approach. Guilford; 2017.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFreeman D, Sheaves B, Goodwin GM, Yu L-M, Nickless A, Harrison PJ, et al. The effects of improving sleep on mental health (OASIS): a randomised controlled trial with mediation analysis. Lancet Psychiatry. 2017;4(10):749\u0026ndash;58.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOng JC, Shapiro SL, Manber R. Combining Mindfulness Meditation with Cognitive-Behavior Therapy for Insomnia: A Treatment-Development Study. Behav Ther. 2008;39(2):171\u0026ndash;82.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAlimoradi Z, Jafari E, Brostr\u0026ouml;m A, Ohayon MM, Lin C-Y, Griffiths MD, et al. Effects of cognitive behavioral therapy for insomnia (CBT-I) on quality of life: A systematic review and meta-analysis. Sleep Med Rev. 2022;64:101646.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGebara MA, Siripong N, DiNapoli EA, Maree RD, Germain A, Reynolds CF, et al. Effect of insomnia treatments on depression: A systematic review and meta-analysis. Depress Anxiety. 2018;35(8):717\u0026ndash;31.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLancee J, Effting M, Van Der Zweerde T, Van Daal L, Van Straten A, Kamphuis JH. Cognitive processes mediate the effects of insomnia treatment: evidence from a randomized wait-list controlled trial. Sleep Med. 2019;54:86\u0026ndash;93.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChow PI, Ingersoll KS, Thorndike FP, Lord HR, Gonder-Frederick L, Morin CM, Ritterband LM. Cognitive mechanisms of sleep outcomes in a randomized clinical trial of internet-based cognitive behavioral therapy for insomnia. Sleep Med. 2018;47:77\u0026ndash;85.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHarvey AG, Dong L, B\u0026eacute;langer L, Morin CM. Mediators and treatment matching in behavior therapy, cognitive therapy and cognitive behavior therapy for chronic insomnia. J Consult Clin Psychol. 2017;85(10):975\u0026ndash;87.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eParsons CE, Zachariae R, Landberger C, Young KS. How does cognitive behavioural therapy for insomnia work? A systematic review and meta-analysis of mediators of change. Clin Psychol Rev. 2021;86:102027.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNorell-Clarke A, Tillfors M, Jansson-Fr\u0026ouml;jmark M, Holl\u0026auml;ndare F, Engstr\u0026ouml;m I. How Does Cognitive Behavioral Therapy for Insomnia Work? An Investigation of Cognitive Processes and Time in Bed as Outcomes and Mediators in a Sample With Insomnia and Depressive Symptomatology. Int J Cogn Therapy. 2017;10(4):304\u0026ndash;29.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBlanken TF, Van Der Zweerde T, Van Straten A, Van Someren EJW, Borsboom D, Lancee J. Introducing Network Intervention Analysis to Investigate Sequential, Symptom-Specific Treatment Effects: A Demonstration in Co-Occurring Insomnia and Depression. Psychother Psychosom. 2019;88(1):52\u0026ndash;4.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-psychology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"psyo","sideBox":"Learn more about [BMC Psychology](http://bmcpsychology.biomedcentral.com/)","snPcode":"","submissionUrl":"","title":"BMC Psychology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"insomnia, mood, mindfulness, university students, group intervention","lastPublishedDoi":"10.21203/rs.3.rs-4617700/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4617700/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground:\u003c/strong\u003e Sleep and mental health problems are very common in university students. The objective of this study was to assess the effectiveness of a multi-component sleep-mood intervention on improving sleep and mental health in university students with clinically significant insomnia symptoms, and to investigate possible mediators.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods:\u003c/strong\u003e Thirty-five participants were randomized to the Sleep Mood Intervention: Live Effectively (SMILE) intervention (n= 23), or wait-list group (n= 12). SMILE is a multi-component group therapy and includes elements of cognitive behavioral therapy for insomnia (CBT-I), mindfulness, and lifestyle modifications, in four weekly two-hour sessions. The primary outcome was insomnia severity. Secondary outcomes were severity of depression and anxiety, and quality of life (QoL). Dysfunctional beliefs and attitudes about sleep and pre-sleep arousal were assessed as mediators.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults:\u003c/strong\u003eIntention-to-treat analysis showed significant time x treatment interaction on insomnia symptoms (\u003cem\u003ep\u003c/em\u003e=.021, \u003cem\u003epartial η²\u003c/em\u003e=.152), with significantly lower insomnia severity for SMILE compared to waitlist at post-test. No significant effects were found on depression, anxiety, and QoL. Dysfunctional beliefs mediated the effect on insomnia severity, but pre-sleep arousal did not.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions:\u003c/strong\u003e This integrated group intervention is associated with reductions in insomnia symptoms in university students. Since no significant effects were detected on mood and QoL, future studies with larger sample size may explore the effects of this intervention on these outcomes.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTrial Registration:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eRegistry: Overzicht van Medisch-wetenschappelijk Onderzoek\u003c/p\u003e\n\u003cp\u003eRegistration number: NL-OMON46359\u003c/p\u003e\n\u003cp\u003eDate of registration: September 18th, 2018\u003c/p\u003e","manuscriptTitle":"Effectiveness of a Multi-component Sleep-Mood Group Intervention on Improving Insomnia in University Students – a Pilot Randomized Controlled Trial","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-07-26 16:50:16","doi":"10.21203/rs.3.rs-4617700/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-07-03T09:34:34+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-07-02T08:28:16+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-07-02T08:27:21+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Psychology","date":"2024-06-21T13:25:31+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-psychology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"psyo","sideBox":"Learn more about [BMC Psychology](http://bmcpsychology.biomedcentral.com/)","snPcode":"","submissionUrl":"","title":"BMC Psychology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"47873ff9-57bd-4194-8c05-ca5798d5967d","owner":[],"postedDate":"July 26th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2024-11-11T16:07:04+00:00","versionOfRecord":{"articleIdentity":"rs-4617700","link":"https://doi.org/10.1186/s40359-024-02057-1","journal":{"identity":"bmc-psychology","isVorOnly":false,"title":"BMC Psychology"},"publishedOn":"2024-11-05 15:57:19","publishedOnDateReadable":"November 5th, 2024"},"versionCreatedAt":"2024-07-26 16:50:16","video":"","vorDoi":"10.1186/s40359-024-02057-1","vorDoiUrl":"https://doi.org/10.1186/s40359-024-02057-1","workflowStages":[]},"version":"v1","identity":"rs-4617700","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4617700","identity":"rs-4617700","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}