Nonrestorative Sleep is Associated with Somatic and Depressive Symptoms in Japanese Junior High School Students

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This study aimed to clarify the factors affecting NRS in Japanese junior high school students. Methods The participants were 529 Japanese junior high school students in grades 7 through 9. Participants were asked to respond to Google Forms, and responses were obtained from 392 students. Sleep habits, history of coronavirus disease (COVID-19), physical symptoms, depressive and symptoms, social isolation, insomnia symptoms, and the presence of symptoms of restless legs syndrome (RLS) were identified. NRS was evaluated using the Restorative Sleep Questionnaire, with scores below 48.5 categorizing participants into the NRS group. Logistic regression analysis was conducted to explore the relationship between NRS and various factors, including sleep duration, insomnia symptoms, RLS symptoms, chronotype, and depressive symptoms. Results The NRS group comprised 30.4% of participants and exhibited a higher prevalence of physical and depressive symptoms compared to those with restorative sleep. Logistic regression analysis, adjusted for sex, grade, and COVID-19 history, revealed the following odds ratios (95% confidence intervals) for NRS: depressive symptoms 3.77 (2.24–6.34), evening chronotype 3.00 (1.62–5.56), RLS symptoms 2.75 (1.12–6.76), and insomnia symptoms 1.92 (1.03–3.57). Conclusions These findings suggest that NRS in Japanese junior high school students is associated with physical and mental health issues. When considering health problems in this population, measures are needed to address the sleep-wake problems associated with NRS. chronotype depression insomnia nonrestorative sleep restless legs syndrome restorative sleep sleep duration Background Nonrestorative sleep (NRS), the inability to feel fully rested and recover from sleep upon awakening, has been shown to be associated with physical and mental health problems in adults. A 2019 meta-analysis found that NRS increases the risk of all-cause mortality and death from cardiovascular disease.[ 1 ] In addition, NRS increases the risk of mortality among adults aged 40–64 years, among short sleepers, and among those aged 65 years and older.[ 2 ] Furthermore, NRS is associated with the development of metabolic syndrome, hypertension, and type 2 diabetes,[ 3 , 4 ] as well as the appearance of depressive symptoms.[ 5 ] NRS is a frequent sleep problem in adolescents as well as adults, occurring almost daily in 17.7% and often in 43.0% of adolescent students in the United States.[ 6 ] In a survey of adolescent students in China, when asked to identify which level of sleep restfulness, from 0 (no sleep rest at all) to 10 (fully rested), they reported that 4.5% scored 0 and had no sleep restfulness at all, with a mean (standard deviation) of 4.5 (2.30).[ 7 ] Few studies have focused on NRS in adolescents, and, to the best of our knowledge, no studies on Japanese adolescents have been reported. Although NRS is caused by a variety of sleep-wake problems, insomnia should also be considered a contributing factor to NRS in adolescents. Insomnia is diagnosed when there is difficulty falling asleep, staying asleep, or waking early in the morning, even with adequate sleep opportunities, and when there are daytime problems related to nighttime sleep difficulties. The prevalence of insomnia in adolescents is nearly 20%,[ 8 – 10 ] and the prevalence of insomnia symptoms is even higher.[ 11 ] Insomnia symptoms that begin in childhood or adolescence often persist into adulthood,[ 12 ] and need to be addressed appropriately. Restless legs syndrome (RLS) should be distinguished from insomnia, as it is a sleep-wake disorder that presents with insomnia-like symptoms. Because RLS symptoms often emerge at bedtime and in the first half of sleep, RLS symptoms can cause difficulty initiating and maintaining sleep.[ 13 ] It is also evident that a substantial number of RLS cases have been inadvertently included in the population conventionally classified as having insomnia, particularly during efforts to identify disease susceptibility genes for insomnia.[ 14 ] The prevalence of RLS in children and adolescents is 1–6%,[ 15 – 21 ] and it is important to consider the possibility of this syndrome when identifying insomnia symptoms. The prevalence of RLS increased after the coronavirus disease (COVID-19) pandemic, and it is necessary to distinguish RLS from insomnia, especially as a potential sequelae of Long COVID. The incidence and prevalence of RLS have increased several-fold, and more severe cases have also increased.[ 22 – 24 ] The affinity of dopaminergic neurons for severe acute respiratory syndrome coronavirus 2 has been shown to be higher than that of other neurons,[ 25 ] which may contribute to the increase in RLS. Therefore, it is necessary to examine whether RLS in children and adolescents has increased after the pandemic. This study aimed to determine the status of mental and physical health and sleep problems among Japanese junior high school students in 2024 after the spread of COVID-19. We confirmed sleep habits, insomnia symptoms, sleep restlessness, and RLS. In addition to anxiety and depressive symptoms, loneliness and isolation were identified as possible psychological problems. Fatiguability, loss of appetite, headache, and abdominal pain were identified as possible physical symptoms. In this study, we focused on NRS and examined and reported sleep-wake problems related to NRS to achieve better sleep health. Methods Participants, Study Design, and Ethical Considerations All students (N = 529) enrolled in a junior high school in Nagasaki City in April 2024 were invited to participate in the study. We distributed an information disclosure document on the "Survey on Sleep Habits and Health Problems" to parents and ensured that parents and students had an opportunity to refuse participation in the study and use of the data. A total of 528 students were asked to respond to the survey, with the exception of one student whose parents requested not to participate in the study. The tablets distributed to all students in the study were used to collect data by requesting responses from Google Forms. All participants were given a randomly generated research ID, and their names and classes were excluded from data analysis. This study was approved by the Nagasaki City Medical Association Ethics Review Committee (approval no. 2023-5). Measures Sociodemographic Information In this study, sex, grade, time of last use of electronic devices, past history of COVID-19, history of COVID-19 vaccination, physical and mental symptoms, insomnia symptoms, and sleep habits were investigated. The frequency of physical symptoms such as headache, abdominal pain, decreased appetite, and fatiguability was divided into the following four categories: "never,” "1 day a week,” "2–4 days a week,” and "more than 5 days a week.” Other items were checked using the following questionnaire. Sleep Habits Sleep habits were assessed using the following seven items, and social jetlag (SJL) was evaluated[ 26 ]: 1. Last awakening time on weekdays, 2. Time of falling asleep on weekdays, 3. Last awakening time on weekends, 4. Time of falling asleep on weekends, 5. Total sleep time on weekdays (TST weekday), 6. Total sleep time on weekends (TST weekend), 7. Ideal total sleep time (ideal TST). From the answers to the above items, we calculated the average sleep time per week (average TST), assuming 5 weekdays and 2 weekends. sleep debt index = ideal TST – average TST average TST = (TST weekday × 5 + TST weekend × 2) / 7 days Weekly sleep loss (wSL) was calculated as follows if the average TST was longer than the TST weekday: wSL = (average TST – TST weekday) × 5. In the other cases, wSL was calculated as follows: wSL = (average TST – TST weekend) × 2. wSLs were categorized into three groups: < 1 h, 1–2 h, and ≥ 2 h. SJL was calculated from mid-sleep time (MST). Relative SJL was calculated by subtracting the weekday MST from the weekend MST, and the absolute value of relative SJL was calculated. Weekends MST was used to assess the chronotype of each individual. The MST of the participants was divided into three groups, approximately equal in number, and categorized as morning, intermediate, and evening types, starting with the early group. However, if the TST weekend was longer than the average TST, the MST on the weekends was corrected as follows: corrected MST weekend = MST weekend – (TST weekend – average TST) / 2. Restorative Sleep Questionnaire The Japanese version of the Restorative Sleep Questionnaire is a 9-item self-administered questionnaire that measures the sense of restfulness obtained from sleeping during the past week.[ 27 , 28 ] Each item is scored from 1 to 5, and the average score of the nine items is converted to a score from 0 to 100. The lower the score, the lower is the perceived recovery. Based on reports from Japanese participants, a score of less than 45.8 was considered to be NRS.[ 27 ] Athens Insomnia Scale The Japanese version of the Athens Insomnia Scale (AIS) is an 8-item self-administered questionnaire that measures insomnia severity.[ 29 , 30 ] It asks for responses to insomnia symptoms and sleep-related daytime problems in the past month. Each item is scored from 0 to 3, and the total score ranges from 0 to 24, with higher scores indicating greater severity of insomnia. The cutoff point between normal participants and those with insomnia is 6 points.[ 29 ] The severity of insomnia is determined as follows: 6–9 points is mild, 10–15 points is moderate, and 16–24 points is severe.[ 31 ] Restless Legs Syndrome Single Question The presence or absence of RLS symptoms was confirmed by the following single question: When you try to relax in the evening or sleep at night, do you ever have unpleasant, restless feelings in your legs that can be relieved by walking or movement?[ 32 ] Those who answered "not at all" for the past 2 weeks were considered the non-RLS group, while the others were considered the RLS group. Furthermore, we divided the RLS group into two groups: those whose symptoms appeared 1 day per week and those whose symptoms appeared 2 or more days per week during the past 2 weeks. Patient Health Questionnaire-9 The Japanese version of the Patient Health Questionnaire-9 (PHQ-9) is a 9-item self-administered questionnaire that measures depressive symptoms.[ 33 , 34 ] Participants answer questions about their symptoms of depression over the past 2 weeks; each item is scored from 0 to 3, and the total score ranges from 0 to 27, with higher scores indicating greater severity of depression. A score of 5 or more indicates the presence of depression.[ 34 ] Generalized Anxiety Disorder-7 The Japanese version of the Generalized Anxiety Disorder-7 is a 7-item self-administered questionnaire that measures anxiety disorders.[ 35 ] The questionnaire asks about anxiety disorders in the past 2 weeks. Each item is scored from 0 to 3, with total scores ranging from 0 to 21, with higher scores indicating greater severity of anxiety disorder. A score of 5 or more indicates the presence of an anxiety disorder.[ 35 ] Three-Item Loneliness Scale The Japanese version of the Three-Item Loneliness Scale is a 3-item self-administered questionnaire that measures loneliness.[ 36 , 37 ] The survey was designed to be easily answered, assuming a large-scale survey using telephones or other means. Each item is scored from 1 to 3, and the total score ranges from 3 to 9, with higher scores indicating a stronger sense of loneliness. Lubben Social Network Scale The abbreviated Japanese version of the Lubben Social Network Scale is a 6-item self-administered questionnaire that measures social networks.[ 38 , 39 ] Each item is scored from 0 to 5 on the family and friends network, and the total score ranges from 0 to 30, with higher scores indicating a larger social network. Statistical analysis Data were analyzed using EZR version 1.68[ 40 ] based on R ver. 4.3.1 ( https://www.r-project.org/ ). Normality was evaluated using the Shapiro–Wilk test. Continuous variables for which normality was confirmed are expressed as mean (standard deviation), and continuous variables for which normality was not observed are expressed as median (interquartile range [IQR]). For comparisons between two groups of continuous variables, an uncorrelated t-test was used for normally distributed variables, and the Mann–Whitney U test was used for non-normally distributed variables. For comparisons between three or more groups of continuous variables, one-way analysis of variance was used for variables that showed normality, the Kruskal–Wallis test was used for variables that showed non-normality, and the Bonferroni method was used for multiple comparisons. Fisher's exact probability test was used to test the independence of the nominal variables. The significance level was set at p < 0.05. Logistic regression analysis with NRS as the dependent variable was adjusted for sex, grade, and past history of COVID-19, and the following variables were entered as independent variables: average TST, AIS score, chronotype, RLS symptoms, and PHQ score. The average TST was categorized into four groups: < 7 h, 7–8 h, 8–9 h (ref), and ≥ 9 h. The AIS scores were categorized into two groups: 6. RLS symptoms were categorized into two groups: those who had symptoms less than 1 day per week, including the non-RLS group, and those who had symptoms 2 or more days per week, with the non-RLS group and those who had symptoms less than 1 day per week as the reference group. The PHQ scores were categorized into two groups: < 5 (ref) and ≥ 5. Results In this survey, 528 students were asked to respond to the questionnaire, and 476 responses were obtained, excluding 52 students who were absent owing to illness or long-term absence. Responses with missing values that would have affected the analysis were excluded, and 392 participants (185 boys and 207 girls) were included in the analysis. As of April 2024, half of the participants had completed the COVID-19 vaccination at least once, and 3/4 of the participants had been affected by COVID-19 at least once (Table 1). Of the participants, 64.0% were aware of fatiguability as a physical symptom, and 36.7% complained of fatigue more than twice a week. A PHQ-9 score of ≥ 5 was reported by 28.6% of the participants and was more common among females. Although the survey was conducted just after the entrance of seventh-grade junior high school students, more seventh-grade students reported feeling anxious, lonely, and lacking a social network compared to other grades (Tables S1 and S2). Sleep duration decreased in the older grades, and students tended to be nocturnal. The median (IQR) average sleep duration was 8.00 (7.29, 8.57) h, and 48.2% of the participants slept for less than 8 h, although the recommended sleep duration for junior high school students is 8–10 h. An AIS score ≥ 6 was reported by 16.8% of the participants. RLS symptoms were observed in 15.8% of the participants, and 7.7% of the participants had symptoms more frequently than 2 days a week (Tables S1 and S2). The NRS group accounted for 30.4% of participants. Compared to the restorative sleep group, the NRS group was more likely to use electronic devices and more likely to use them late after 23:00. The NRS group was more likely to have physical symptoms, such as headache, abdominal pain, loss of appetite, and fatiguability, as well as depressive symptoms, while there was no association with anxiety, loneliness, or a lack of social networks (Table 2). Compared with the restorative sleep group, the NRS group had higher rates of AIS score ≥ 6, difficulty waking, and RLS symptoms. Sleep duration was shorter in the NRS group, reflecting the later time of sleep onset not only on weekdays but also on weekends. The chronotype tended to be evening-type, and sleep loss and SJL were prominent (Table 3). In the multivariate analysis with NRS as the dependent variable, short sleep duration, which was significant in the univariate analysis, was not significant. An AIS score ≥ 6, evening chronotype, RLS symptoms at least twice a week, and a PHQ score ≥ 6 were identified as significant factors. The odds ratios (95% confidence intervals) for NRS were as follows: depressive symptoms 3.77 (2.24–6.34), evening chronotype 3.00 (1.62–5.56), RLS symptoms 2.75 (1.12–6.76), and insomnia symptoms 1.92 (1.03–3.57) (Table 4). Discussion Japanese junior high school students with fatiguability and depressive symptoms accounted for approximately 30% of the total number of students. NRS was also observed in approximately 30% of the students. The presence of NRS was significantly associated with mental and physical problems. Insomnia symptoms, evening chronotype, and RLS symptoms were identified as sleep problems associated with NRS. To achieve sleep health for adolescents to lead healthy lives, measures focusing on individual sleep problems are needed. The NRS is associated with difficulty in waking. When adolescents wake up spontaneously in the morning and are able to get out of bed promptly, they often experience a sense of restorative sleep. If they have to repeatedly rely on an alarm or be repeatedly woken up by family members, their performance in the morning may decline, along with their likelihood of maintaining the habit of eating breakfast.[ 41 ] Adolescents and their families can feel the difficulty of waking up every day, and it is necessary to take measures from the night before to start the morning with a sense of restorative sleep. In this study, the prevalence of symptomatic participants suspected of having RLS was higher than expected and was an important factor associated with NRS. Although the prevalence and incidence of RLS in adults are increasing with the spread of COVID-19 worldwide,[ 22 – 24 ] to our knowledge, there are no reports of RLS in children and adolescents. RLS symptoms emerge during the night and late at night, which may cause not only insomnia but also the evening chronotype with late onset of sleep. The epidemiology and clinical findings of RLS in children and adolescents need to be re-examined. In this study, short sleep duration was associated with NRS in the univariate analysis but was not a significant factor in the multivariate analysis. It is widely known that short sleep durations increase the risk of mental and physical health problems. In the present study, we could not establish categories for multivariate analysis because of the small number of participants who slept for less than 6 h. Further studies with a larger number of participants are needed to clarify the effects of short sleep durations. This study had some limitations. First, the questionnaires used in this study were the same as those used with adults. There is a concern that the respondents may have encountered difficulties with questions and answers that were hard to understand. The valid response rate of 82.4% was low, which may have been due to the content of the questionnaire. For example, the Patient Health Questionnaire for Adolescents (PHQ-A) has been developed for the PHQ-9 for adolescent participants.[ 42 ] Although a validated Japanese version of the PHQ-A has not been published, a questionnaire for this age group should be utilized whenever possible, and sufficient consideration should be given when an appropriate questionnaire is not available. Second, the present study could not include information on absenteeism, which corresponds to approximately 10% of the target population, because the responses were requested at school. There is a concern that some absent students may have sleep-wake problems. The inclusion of responses from absent students may have resulted in a higher number of students with problems. Third, there is a lack of comprehensive evaluation of the daily changes in sleep-wake problems associated with NRS. In addition to insomnia, RLS, and circadian rhythm sleep-wake disorder, NRS is also observed in long-sleepers and patients with hypersomnia, in whom the effects of sleep insufficiency are more likely to become apparent. Obstructive sleep apnea and periodic limb movement disorder, which cause poor sleep quality, also affect NRS. There is a need for a more comprehensive evaluation of sleep-wake problems because questionnaires alone have limitations. In conclusion, NRS is associated with physical and mental health problems among Japanese junior high school students. Insomnia, evening chronotype, and RLS are associated with NRS, and measures to address sleep-wake problems in adolescents targeting the improvement of NRS are needed. The present study indicates the importance of addressing sleep onset difficulties and preventing excessive delays in sleep phases, which can be achieved through sleep health education. In addition, considering the diversity of sleep and individual differences, it is crucial to assist individuals and their families in understanding their specific sleep-wake challenges and developing self-care strategies. Moreover, it is necessary to establish a system of medical cooperation between schools, pediatricians, and specialized medical institutions to link children to medical care when self-care alone is insufficient. Abbreviations AIS Athens Insomnia Scale COVID-19 coronavirus disease IQR interquartile range MST Mid-Sleep Time NRS nonrestorative sleep PHQ-9 Patient Health Questionnaire-9 PHQ-A Patient Health Questionnaire for Adolescents RLS restless legs syndrome SJL social jetlag TST total sleep time wSL weekly sleep loss Declarations Ethics approval and consent to participate All procedures performed in this study involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. This study was approved by the Nagasaki City Medical Association Ethics Review Committee (approval no. 2023-5). Consent for publication Not applicable. Availability of data and materials The datasets used and/or analyzed during the current study are available from the corresponding author upon reasonable request. Competing interests The author declare that they have no conflicts of interest. Funding No funding was received for conducting this study. Author’s contributions YN is the sole author of all parts of this manuscript. The author conceived this study, collected the data, performed the analysis, and drafted the manuscript. The author read and approved the final manuscript. Acknowledgements We would like to thank Yuto Honda, Yuko Matsuo, and Yukari Shimazaki for their cooperation in this study, conducted at a junior high school. We also thank Dr. Hideaki Kondo of the Department of General Medicine, Nagasaki University Hospital for his extensive guidance and advice on this study. We would like to express our deep appreciation for the cooperation of all those involved, including the students and their parents, who participated in this study. References Ge L, Guyatt G, Tian J, Pan B, Chang Y, Chen Y, et al. 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The PHQ-9: Validity of a brief depression severity measure. Journal of General Internal Medicine. 2001;16(9):606-13. doi: 10.1046/j.1525-1497.2001.016009606.x. Spitzer RL, Kroenke K, Williams JB, Löwe B. A brief measure for assessing generalized anxiety disorder: the GAD-7. Arch Intern Med. 2006;166(10):1092-7. doi: 10.1001/archinte.166.10.1092. Igarashi T. Development of the Japanese version of the three-item loneliness scale. BMC Psychology. 2019;7(1):20. doi: 10.1186/s40359-019-0285-0. Hughes ME, Waite LJ, Hawkley LC, Cacioppo JT. A Short Scale for Measuring Loneliness in Large Surveys: Results From Two Population-Based Studies. Research on Aging. 2004;26(6):655-72. doi: 10.1177/0164027504268574. Kurimoto A, Awata S, Ohkubo T, Tsubota-Utsugi M, Asayama K, Takahashi K, et al. [Reliability and validity of the Japanese version of the abbreviated Lubben Social Network Scale]. Nihon Ronen Igakkai Zasshi. 2011;48(2):149-57. doi: 10.3143/geriatrics.48.149. Lubben J, Blozik E, Gillmann G, Iliffe S, von Renteln Kruse W, Beck JC, et al. Performance of an abbreviated version of the Lubben Social Network Scale among three European community-dwelling older adult populations. Gerontologist. 2006;46(4):503-13. doi: 10.1093/geront/46.4.503. Kanda Y. Investigation of the freely available easy-to-use software ‘EZR’ for medical statistics. Bone marrow transplantation. 2013;48(3):452-8. doi: 10.1038/bmt.2012.244. Arakawa M, Taira K, Tanaka H, Yamakawa K, Toguchi H, Kadekaru H, et al. A survey of junior high school students' sleep habit and lifestyle in Okinawa. Psychiatry Clin Neurosci. 2001;55(3):211-2. doi: 10.1046/j.1440-1819.2001.00829.x. Johnson JG, Harris ES, Spitzer RL, Williams JBW. The patient health questionnaire for adolescents: Validation of an instrument for the assessment of mental disorders among adolescent primary care patients. Journal of Adolescent Health. 2002;30(3):196-204. doi: https://doi.org/10.1016/S1054-139X(01)00333-0. Tables Table 1. Demographic characteristics n 392 Grade seventh, n (%) 122 (31.1) eighth, n (%) 143 (36.5) ninth, n (%) 127 (32.4) Electronic devices user, n (%) 257 (65.6) Last electronic devices usage time 257 (65.6) < 21:00, n (%) 59 (15.1) 21:00–22:00, n (%) 76 (19.4) 22:00–23:00, n (%) 128 (32.7) ≥ 23:00, n (%) 129 (32.9) Past history of COVID-19, n (%) 296 (75.5) COVID-19 unvaccinated person, n (%) 195 (49.7) COVID-19: coronavirus disease Table 2. Comparisons of demographic and psychosomatic symptoms between restorative sleep (RS) group and nonrestorative sleep (NRS) group RS group NRS group P value n 273 119 392 Male, n (%) 137 (50.2) 48 (40.3) 0.08 Grade seventh, n (%) 89 (32.6) 33 (27.7) 0.52 eighth, n (%) 100 (36.6) 43 (36.1) ninth, n (%) 84 (30.8) 43 (36.1) Electronic devices user, n (%) 169 (61.9) 88 (73.9) 0.02 Last electronic devices usage time < 21:00, n (%) 44 (16.1) 15 (12.6) 0.006 21:00–22:00, n (%) 60 (22.0) 16 (13.4) 22:00–23:00, n (%) 94 (34.4) 34 (28.6) ≥ 23:00, n (%) 75 (27.5) 54 (45.4) Headache, n (%) 74 (31.6) 60 (59.4) < 0.001 ≥ 2 days/week, n (%) 19 (7.0) 32 (26.9) < 0.001 Abdominal pain, n (%) 76 (27.8) 61 (51.3) < 0.001 ≥ 2 days/week, n (%) 25 (9.2) 23 (19.3) 0.007 Appetite loss, n (%) 38 (13.9) 40 (33.6) < 0.001 ≥ 2 days/week, n (%) 13 (4.8) 18 (15.1) 0.001 Fatiguability, n (%) 148 (54.2) 103 (86.6) < 0.001 ≥ 2 days/week, n (%) 71 (26.0) 73 (61.3) < 0.001 Past history of COVID-19, n (%) 206 (75.5) 90 (75.6) 1 COVID-19 unvaccinated person, n (%) 135 (49.5) 60 (50.4) 0.10 PHQ-9 score, median (IQR) 1.0 (0.0, 4.0) 5.0 (2.0, 9.0) < 0.001 PHQ-9 score ≥ 5, n (%) 50 (18.3) 62 (52.1) < 0.001 GAD-7 score, median (IQR) 1.0 (0.0, 4.0) 1.0 (0.0, 3.0) 0.71 GAD-7 score ≥ 5, n (%) 51 (18.7) 23 (19.3) 0.89 Loneliness scale score, median (IQR) 3.0 (3.0, 4.0) 3.0 (3.0, 4.0) 0.60 Loneliness scale score ≥ 6, n (%) 27 (9.9) 7 (5.9) 0.24 LSNS-6 score, median (IQR) 21.0 (16.0, 24.0) 21.0 (17.0, 26.0) 0.22 LSNS-6 score ≥ 12, n (%) 32 (11.7) 8 (6.7) 0.15 IQR: Interquartile range, GAD: Generalized Anxiety Disorder, LSNS-6: Lubben Social Network Scale-6, NRS: nonrestorative sleep, PHQ: Patient Health Questionnaire, RS: Restorative sleep, RSQ: Restorative Sleep Questionnaire. Table 3. Comparisons of sleep characteristics between restorative sleep (RS) group and nonrestorative sleep (NRS) group RS group NRS group P value n 273 119 392 AIS score, median (IQR) 2.0 (1.0, 4.0) 4.0 (2.0, 6.0) < 0.001 AIS score ≥ 6, n (%) 31 (11.4) 35 (29.4) < 0.001 RSQ score, median (IQR) 65.6 (56.3, 78.1) 37.5 (31.3, 40.6) < 0.001 Difficulty getting up, n (%) 44 (16.1) 48 (40.3) < 0.001 RLS symptoms, n (%) 30 (11.0) 32 (26.9) < 0.001 ≥ 2 days/week, n (%) 13 (4.8) 17 (14.3) 0.003 Average sleep duration h, median (IQR) 8.00 (7.50, 8.57) 7.79 (7.04, 8.39) 0.01 < 7 hours, n (%) 33 (12.1) 29 (24.4) 0.02 7–8 hours, n (%) 88 (32.2) 39 (32.8) 8–9 hours, n (%) 112 (41.0) 39 (32.8) ≥ 9 hours, n (%) 40 (14.7) 12 (10.1) Ideal sleep duration h, median (IQR) 9.00 (8.00, 10.00) 9.00 (8.00, 10.00) 0.31 Weekday sleep habits Sleep duration h, median (IQR) 8.00 (7.00, 8.00) 7.50 (6.50, 8.00) 0.006 Falling asleep time, h:mm, median (IQR) 22:50 (22:00, 23:30) 23:00 (22:35, 23:30) < 0.001 Last waking up time, h:mm, median (IQR) 6:30 (6:30, 7:00) 6:40 (6:25, 7:00) 0.84 Weekday sleep habits Sleep duration h, median (IQR) 8.50 (8.00, 10.00) 9.00 (8.00, 10.00) 0.98 Falling asleep time, h:mm, median (IQR) 23:00 (22:30, 23:30) 23:30 (23:00, 0:00) < 0.001 Last waking up time, h:mm, median (IQR) 8:00 (7:00, 9:00) 8:30 (7:30, 9:45) 0.001 Corrected mid-sleep time, h:mm, median (IQR) 3:09 (2:38, 3:33) 3:29 (3:03, 4:17) < 0.001 Chronotype Morning type 106 (38.8) 25 (21.0) < 0.001 Intermediate type 95 (34.8) 36 (30.3) Evening type 72 (26.4) 58 (48.7) Weekly sleep loss, h, median (IQR) 1.43 (0.71, 2.86) 2.14 (1.43, 2.86) 0.007 < 1 hour, n (%) 168 (61.5) 53 (44.5) 0.007 1–2 hours, n (%) 72 (26.4) 46 (38.7) ≥ 2 hours, n (%) 33 (12.1) 20 (16.8) SJL, mm, median (IQR) 57.5 (30.0, 80.0) 75.0 (37.5, 123.3) < 0.001 AIS: Athens Insomnia Scale, IQR: Interquartile range, RLS: restless legs syndrome, RSQ: Restorative Sleep Questionnaire, SJL: social Jetlag. Table 4. Logistic regression analysis for nonrestorative sleep Univariable analysis Multivariable analysis* Odds ratio (95% CI) Odds ratio (95% CI) Average total sleep time < 7 hr 2.52 (1.36-4.68) 1.53 (0.76-3.09) 7–8 hr 1.27 (0.75-2.15) 0.91 (0.51-1.65) 8–9 hr 1 1 ≥ 9 hr 0.86 (0.41-1.81) 0.68 (0.30-1.57) Athens Insomnia Scale score 3.25 (1.89-5.60) 1.92 (1.03-3.57) < 6 1 1 ≥ 6 3.25 (1.89-5.60) 1.92 (1.03-3.57) Chronotype Morning type 1 1 Intermediate type 1.61 (0.90-2.87) 1.54 (0.81-2.90) Evening type 3.42 (1.96-5.96) 3.00 (1.62-5.56) RLS symptoms < 2 days/week or symptom-free 1 1 ≥ 2 days/week 2.98 (1.71-5.19) 2.75 (1.12-6.76) PHQ-9 < 5 1 1 ≥ 5 4.85 (3.02-7.78) 3.77 (2.24-6.34) *Adjusted for sex, grade, and past history of COVID-19. CI: confidence interval, PHQ: Patient Health Questionnaire, RLS: restless legs syndrome. Additional Declarations No competing interests reported. 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A 2019 meta-analysis found that NRS increases the risk of all-cause mortality and death from cardiovascular disease.[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e] In addition, NRS increases the risk of mortality among adults aged 40\u0026ndash;64 years, among short sleepers, and among those aged 65 years and older.[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e] Furthermore, NRS is associated with the development of metabolic syndrome, hypertension, and type 2 diabetes,[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e] as well as the appearance of depressive symptoms.[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eNRS is a frequent sleep problem in adolescents as well as adults, occurring almost daily in 17.7% and often in 43.0% of adolescent students in the United States.[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e] In a survey of adolescent students in China, when asked to identify which level of sleep restfulness, from 0 (no sleep rest at all) to 10 (fully rested), they reported that 4.5% scored 0 and had no sleep restfulness at all, with a mean (standard deviation) of 4.5 (2.30).[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] Few studies have focused on NRS in adolescents, and, to the best of our knowledge, no studies on Japanese adolescents have been reported.\u003c/p\u003e \u003cp\u003eAlthough NRS is caused by a variety of sleep-wake problems, insomnia should also be considered a contributing factor to NRS in adolescents. Insomnia is diagnosed when there is difficulty falling asleep, staying asleep, or waking early in the morning, even with adequate sleep opportunities, and when there are daytime problems related to nighttime sleep difficulties. The prevalence of insomnia in adolescents is nearly 20%,[\u003cspan additionalcitationids=\"CR9\" citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e] and the prevalence of insomnia symptoms is even higher.[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e] Insomnia symptoms that begin in childhood or adolescence often persist into adulthood,[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e] and need to be addressed appropriately.\u003c/p\u003e \u003cp\u003eRestless legs syndrome (RLS) should be distinguished from insomnia, as it is a sleep-wake disorder that presents with insomnia-like symptoms. Because RLS symptoms often emerge at bedtime and in the first half of sleep, RLS symptoms can cause difficulty initiating and maintaining sleep.[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e] It is also evident that a substantial number of RLS cases have been inadvertently included in the population conventionally classified as having insomnia, particularly during efforts to identify disease susceptibility genes for insomnia.[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] The prevalence of RLS in children and adolescents is 1\u0026ndash;6%,[\u003cspan additionalcitationids=\"CR16 CR17 CR18 CR19 CR20\" citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e] and it is important to consider the possibility of this syndrome when identifying insomnia symptoms.\u003c/p\u003e \u003cp\u003eThe prevalence of RLS increased after the coronavirus disease (COVID-19) pandemic, and it is necessary to distinguish RLS from insomnia, especially as a potential sequelae of Long COVID. The incidence and prevalence of RLS have increased several-fold, and more severe cases have also increased.[\u003cspan additionalcitationids=\"CR23\" citationid=\"CR23\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e24\u003c/span\u003e] The affinity of dopaminergic neurons for severe acute respiratory syndrome coronavirus 2 has been shown to be higher than that of other neurons,[\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e25\u003c/span\u003e] which may contribute to the increase in RLS. Therefore, it is necessary to examine whether RLS in children and adolescents has increased after the pandemic.\u003c/p\u003e \u003cp\u003eThis study aimed to determine the status of mental and physical health and sleep problems among Japanese junior high school students in 2024 after the spread of COVID-19. We confirmed sleep habits, insomnia symptoms, sleep restlessness, and RLS. In addition to anxiety and depressive symptoms, loneliness and isolation were identified as possible psychological problems. Fatiguability, loss of appetite, headache, and abdominal pain were identified as possible physical symptoms. In this study, we focused on NRS and examined and reported sleep-wake problems related to NRS to achieve better sleep health.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eParticipants, Study Design, and Ethical Considerations\u003c/h2\u003e \u003cp\u003e All students (N\u0026thinsp;=\u0026thinsp;529) enrolled in a junior high school in Nagasaki City in April 2024 were invited to participate in the study. We distributed an information disclosure document on the \"Survey on Sleep Habits and Health Problems\" to parents and ensured that parents and students had an opportunity to refuse participation in the study and use of the data. A total of 528 students were asked to respond to the survey, with the exception of one student whose parents requested not to participate in the study. The tablets distributed to all students in the study were used to collect data by requesting responses from Google Forms. All participants were given a randomly generated research ID, and their names and classes were excluded from data analysis. This study was approved by the Nagasaki City Medical Association Ethics Review Committee (approval no. 2023-5).\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eMeasures\u003c/h3\u003e\n\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eSociodemographic Information\u003c/h2\u003e \u003cp\u003eIn this study, sex, grade, time of last use of electronic devices, past history of COVID-19, history of COVID-19 vaccination, physical and mental symptoms, insomnia symptoms, and sleep habits were investigated. The frequency of physical symptoms such as headache, abdominal pain, decreased appetite, and fatiguability was divided into the following four categories: \"never,\u0026rdquo; \"1 day a week,\u0026rdquo; \"2\u0026ndash;4 days a week,\u0026rdquo; and \"more than 5 days a week.\u0026rdquo; Other items were checked using the following questionnaire.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eSleep Habits\u003c/h3\u003e\n\u003cp\u003eSleep habits were assessed using the following seven items, and social jetlag (SJL) was evaluated[\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e26\u003c/span\u003e]: 1. Last awakening time on weekdays, 2. Time of falling asleep on weekdays, 3. Last awakening time on weekends, 4. Time of falling asleep on weekends, 5. Total sleep time on weekdays (TST weekday), 6. Total sleep time on weekends (TST weekend), 7. Ideal total sleep time (ideal TST). From the answers to the above items, we calculated the average sleep time per week (average TST), assuming 5 weekdays and 2 weekends.\u003c/p\u003e \u003cp\u003esleep debt index\u0026thinsp;=\u0026thinsp;ideal TST \u0026ndash; average TST\u003c/p\u003e \u003cp\u003eaverage TST = (TST weekday \u0026times; 5\u0026thinsp;+\u0026thinsp;TST weekend \u0026times; 2) / 7 days\u003c/p\u003e \u003cp\u003eWeekly sleep loss (wSL) was calculated as follows if the average TST was longer than the TST weekday: wSL = (average TST \u0026ndash; TST weekday) \u0026times; 5. In the other cases, wSL was calculated as follows: wSL = (average TST \u0026ndash; TST weekend) \u0026times; 2. wSLs were categorized into three groups: \u0026lt; 1 h, 1\u0026ndash;2 h, and \u0026ge;\u0026thinsp;2 h. SJL was calculated from mid-sleep time (MST). Relative SJL was calculated by subtracting the weekday MST from the weekend MST, and the absolute value of relative SJL was calculated.\u003c/p\u003e \u003cp\u003eWeekends MST was used to assess the chronotype of each individual. The MST of the participants was divided into three groups, approximately equal in number, and categorized as morning, intermediate, and evening types, starting with the early group. However, if the TST weekend was longer than the average TST, the MST on the weekends was corrected as follows: corrected MST weekend\u0026thinsp;=\u0026thinsp;MST weekend \u0026ndash; (TST weekend \u0026ndash; average TST) / 2.\u003c/p\u003e\n\u003ch3\u003eRestorative Sleep Questionnaire\u003c/h3\u003e\n\u003cp\u003eThe Japanese version of the Restorative Sleep Questionnaire is a 9-item self-administered questionnaire that measures the sense of restfulness obtained from sleeping during the past week.[\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e28\u003c/span\u003e] Each item is scored from 1 to 5, and the average score of the nine items is converted to a score from 0 to 100. The lower the score, the lower is the perceived recovery. Based on reports from Japanese participants, a score of less than 45.8 was considered to be NRS.[\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e27\u003c/span\u003e]\u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eAthens Insomnia Scale\u003c/h2\u003e \u003cp\u003eThe Japanese version of the Athens Insomnia Scale (AIS) is an 8-item self-administered questionnaire that measures insomnia severity.[\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e29\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e30\u003c/span\u003e] It asks for responses to insomnia symptoms and sleep-related daytime problems in the past month. Each item is scored from 0 to 3, and the total score ranges from 0 to 24, with higher scores indicating greater severity of insomnia. The cutoff point between normal participants and those with insomnia is 6 points.[\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e29\u003c/span\u003e] The severity of insomnia is determined as follows: 6\u0026ndash;9 points is mild, 10\u0026ndash;15 points is moderate, and 16\u0026ndash;24 points is severe.[\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e31\u003c/span\u003e]\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eRestless Legs Syndrome Single Question\u003c/h3\u003e\n\u003cp\u003eThe presence or absence of RLS symptoms was confirmed by the following single question: When you try to relax in the evening or sleep at night, do you ever have unpleasant, restless feelings in your legs that can be relieved by walking or movement?[\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e32\u003c/span\u003e] Those who answered \"not at all\" for the past 2 weeks were considered the non-RLS group, while the others were considered the RLS group. Furthermore, we divided the RLS group into two groups: those whose symptoms appeared 1 day per week and those whose symptoms appeared 2 or more days per week during the past 2 weeks.\u003c/p\u003e\n\u003ch3\u003ePatient Health Questionnaire-9\u003c/h3\u003e\n\u003cp\u003eThe Japanese version of the Patient Health Questionnaire-9 (PHQ-9) is a 9-item self-administered questionnaire that measures depressive symptoms.[\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e33\u003c/span\u003e, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e34\u003c/span\u003e] Participants answer questions about their symptoms of depression over the past 2 weeks; each item is scored from 0 to 3, and the total score ranges from 0 to 27, with higher scores indicating greater severity of depression. A score of 5 or more indicates the presence of depression.[\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e34\u003c/span\u003e]\u003c/p\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eGeneralized Anxiety Disorder-7\u003c/h2\u003e \u003cp\u003eThe Japanese version of the Generalized Anxiety Disorder-7 is a 7-item self-administered questionnaire that measures anxiety disorders.[\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e35\u003c/span\u003e] The questionnaire asks about anxiety disorders in the past 2 weeks. Each item is scored from 0 to 3, with total scores ranging from 0 to 21, with higher scores indicating greater severity of anxiety disorder. A score of 5 or more indicates the presence of an anxiety disorder.[\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e35\u003c/span\u003e]\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eThree-Item Loneliness Scale\u003c/h2\u003e \u003cp\u003eThe Japanese version of the Three-Item Loneliness Scale is a 3-item self-administered questionnaire that measures loneliness.[\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e36\u003c/span\u003e, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e37\u003c/span\u003e] The survey was designed to be easily answered, assuming a large-scale survey using telephones or other means. Each item is scored from 1 to 3, and the total score ranges from 3 to 9, with higher scores indicating a stronger sense of loneliness.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eLubben Social Network Scale\u003c/h2\u003e \u003cp\u003eThe abbreviated Japanese version of the Lubben Social Network Scale is a 6-item self-administered questionnaire that measures social networks.[\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e38\u003c/span\u003e, \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e39\u003c/span\u003e] Each item is scored from 0 to 5 on the family and friends network, and the total score ranges from 0 to 30, with higher scores indicating a larger social network.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eData were analyzed using EZR version 1.68[\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e40\u003c/span\u003e] based on R ver. 4.3.1 (\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.r-project.org/\u003c/span\u003e\u003cspan address=\"https://www.r-project.org/\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e). Normality was evaluated using the Shapiro\u0026ndash;Wilk test. Continuous variables for which normality was confirmed are expressed as mean (standard deviation), and continuous variables for which normality was not observed are expressed as median (interquartile range [IQR]). For comparisons between two groups of continuous variables, an uncorrelated t-test was used for normally distributed variables, and the Mann\u0026ndash;Whitney U test was used for non-normally distributed variables. For comparisons between three or more groups of continuous variables, one-way analysis of variance was used for variables that showed normality, the Kruskal\u0026ndash;Wallis test was used for variables that showed non-normality, and the Bonferroni method was used for multiple comparisons. Fisher's exact probability test was used to test the independence of the nominal variables. The significance level was set at p\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e \u003cp\u003eLogistic regression analysis with NRS as the dependent variable was adjusted for sex, grade, and past history of COVID-19, and the following variables were entered as independent variables: average TST, AIS score, chronotype, RLS symptoms, and PHQ score. The average TST was categorized into four groups: \u0026lt; 7 h, 7\u0026ndash;8 h, 8\u0026ndash;9 h (ref), and \u0026ge;\u0026thinsp;9 h. The AIS scores were categorized into two groups: \u0026lt; 6 (ref) and \u0026gt;\u0026thinsp;6. RLS symptoms were categorized into two groups: those who had symptoms less than 1 day per week, including the non-RLS group, and those who had symptoms 2 or more days per week, with the non-RLS group and those who had symptoms less than 1 day per week as the reference group. The PHQ scores were categorized into two groups: \u0026lt; 5 (ref) and \u0026ge;\u0026thinsp;5.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eIn this survey, 528 students were asked to respond to the questionnaire, and 476 responses were obtained, excluding 52 students who were absent owing to illness or long-term absence. Responses with missing values that would have affected the analysis were excluded, and 392 participants (185 boys and 207 girls) were included in the analysis. As of April 2024, half of the participants had completed the COVID-19 vaccination at least once, and 3/4 of the participants had been affected by COVID-19 at least once (Table\u0026nbsp;1).\u003c/p\u003e \u003cp\u003eOf the participants, 64.0% were aware of fatiguability as a physical symptom, and 36.7% complained of fatigue more than twice a week. A PHQ-9 score of \u0026ge;\u0026thinsp;5 was reported by 28.6% of the participants and was more common among females. Although the survey was conducted just after the entrance of seventh-grade junior high school students, more seventh-grade students reported feeling anxious, lonely, and lacking a social network compared to other grades (Tables S1 and S2).\u003c/p\u003e \u003cp\u003eSleep duration decreased in the older grades, and students tended to be nocturnal. The median (IQR) average sleep duration was 8.00 (7.29, 8.57) h, and 48.2% of the participants slept for less than 8 h, although the recommended sleep duration for junior high school students is 8\u0026ndash;10 h. An AIS score\u0026thinsp;\u0026ge;\u0026thinsp;6 was reported by 16.8% of the participants. RLS symptoms were observed in 15.8% of the participants, and 7.7% of the participants had symptoms more frequently than 2 days a week (Tables S1 and S2).\u003c/p\u003e \u003cp\u003eThe NRS group accounted for 30.4% of participants. Compared to the restorative sleep group, the NRS group was more likely to use electronic devices and more likely to use them late after 23:00. The NRS group was more likely to have physical symptoms, such as headache, abdominal pain, loss of appetite, and fatiguability, as well as depressive symptoms, while there was no association with anxiety, loneliness, or a lack of social networks (Table\u0026nbsp;2).\u003c/p\u003e \u003cp\u003eCompared with the restorative sleep group, the NRS group had higher rates of AIS score\u0026thinsp;\u0026ge;\u0026thinsp;6, difficulty waking, and RLS symptoms. Sleep duration was shorter in the NRS group, reflecting the later time of sleep onset not only on weekdays but also on weekends. The chronotype tended to be evening-type, and sleep loss and SJL were prominent (Table\u0026nbsp;3).\u003c/p\u003e \u003cp\u003eIn the multivariate analysis with NRS as the dependent variable, short sleep duration, which was significant in the univariate analysis, was not significant. An AIS score\u0026thinsp;\u0026ge;\u0026thinsp;6, evening chronotype, RLS symptoms at least twice a week, and a PHQ score\u0026thinsp;\u0026ge;\u0026thinsp;6 were identified as significant factors. The odds ratios (95% confidence intervals) for NRS were as follows: depressive symptoms 3.77 (2.24\u0026ndash;6.34), evening chronotype 3.00 (1.62\u0026ndash;5.56), RLS symptoms 2.75 (1.12\u0026ndash;6.76), and insomnia symptoms 1.92 (1.03\u0026ndash;3.57) (Table\u0026nbsp;4).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eJapanese junior high school students with fatiguability and depressive symptoms accounted for approximately 30% of the total number of students. NRS was also observed in approximately 30% of the students. The presence of NRS was significantly associated with mental and physical problems. Insomnia symptoms, evening chronotype, and RLS symptoms were identified as sleep problems associated with NRS. To achieve sleep health for adolescents to lead healthy lives, measures focusing on individual sleep problems are needed.\u003c/p\u003e \u003cp\u003eThe NRS is associated with difficulty in waking. When adolescents wake up spontaneously in the morning and are able to get out of bed promptly, they often experience a sense of restorative sleep. If they have to repeatedly rely on an alarm or be repeatedly woken up by family members, their performance in the morning may decline, along with their likelihood of maintaining the habit of eating breakfast.[\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e41\u003c/span\u003e] Adolescents and their families can feel the difficulty of waking up every day, and it is necessary to take measures from the night before to start the morning with a sense of restorative sleep.\u003c/p\u003e \u003cp\u003eIn this study, the prevalence of symptomatic participants suspected of having RLS was higher than expected and was an important factor associated with NRS. Although the prevalence and incidence of RLS in adults are increasing with the spread of COVID-19 worldwide,[\u003cspan additionalcitationids=\"CR23\" citationid=\"CR23\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e24\u003c/span\u003e] to our knowledge, there are no reports of RLS in children and adolescents. RLS symptoms emerge during the night and late at night, which may cause not only insomnia but also the evening chronotype with late onset of sleep. The epidemiology and clinical findings of RLS in children and adolescents need to be re-examined.\u003c/p\u003e \u003cp\u003eIn this study, short sleep duration was associated with NRS in the univariate analysis but was not a significant factor in the multivariate analysis. It is widely known that short sleep durations increase the risk of mental and physical health problems. In the present study, we could not establish categories for multivariate analysis because of the small number of participants who slept for less than 6 h. Further studies with a larger number of participants are needed to clarify the effects of short sleep durations.\u003c/p\u003e \u003cp\u003eThis study had some limitations. First, the questionnaires used in this study were the same as those used with adults. There is a concern that the respondents may have encountered difficulties with questions and answers that were hard to understand. The valid response rate of 82.4% was low, which may have been due to the content of the questionnaire. For example, the Patient Health Questionnaire for Adolescents (PHQ-A) has been developed for the PHQ-9 for adolescent participants.[\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e42\u003c/span\u003e] Although a validated Japanese version of the PHQ-A has not been published, a questionnaire for this age group should be utilized whenever possible, and sufficient consideration should be given when an appropriate questionnaire is not available. Second, the present study could not include information on absenteeism, which corresponds to approximately 10% of the target population, because the responses were requested at school. There is a concern that some absent students may have sleep-wake problems. The inclusion of responses from absent students may have resulted in a higher number of students with problems. Third, there is a lack of comprehensive evaluation of the daily changes in sleep-wake problems associated with NRS. In addition to insomnia, RLS, and circadian rhythm sleep-wake disorder, NRS is also observed in long-sleepers and patients with hypersomnia, in whom the effects of sleep insufficiency are more likely to become apparent. Obstructive sleep apnea and periodic limb movement disorder, which cause poor sleep quality, also affect NRS. There is a need for a more comprehensive evaluation of sleep-wake problems because questionnaires alone have limitations.\u003c/p\u003e \u003cp\u003eIn conclusion, NRS is associated with physical and mental health problems among Japanese junior high school students. Insomnia, evening chronotype, and RLS are associated with NRS, and measures to address sleep-wake problems in adolescents targeting the improvement of NRS are needed. The present study indicates the importance of addressing sleep onset difficulties and preventing excessive delays in sleep phases, which can be achieved through sleep health education. In addition, considering the diversity of sleep and individual differences, it is crucial to assist individuals and their families in understanding their specific sleep-wake challenges and developing self-care strategies. Moreover, it is necessary to establish a system of medical cooperation between schools, pediatricians, and specialized medical institutions to link children to medical care when self-care alone is insufficient.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eAIS\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Athens Insomnia Scale\u003c/p\u003e\n\u003cp\u003eCOVID-19 \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;coronavirus disease\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIQR\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;interquartile range\u003c/p\u003e\n\u003cp\u003eMST\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Mid-Sleep Time\u003c/p\u003e\n\u003cp\u003eNRS\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;nonrestorative sleep\u003c/p\u003e\n\u003cp\u003ePHQ-9\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Patient Health Questionnaire-9\u003c/p\u003e\n\u003cp\u003ePHQ-A\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Patient Health Questionnaire for Adolescents\u003c/p\u003e\n\u003cp\u003eRLS\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;restless legs syndrome\u003c/p\u003e\n\u003cp\u003eSJL\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;social jetlag\u003c/p\u003e\n\u003cp\u003eTST\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;total sleep time\u003c/p\u003e\n\u003cp\u003ewSL \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; weekly sleep loss\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003e\u003cem\u003eEthics approval and consent to participate\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll procedures performed in this study involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. This study was approved by the Nagasaki City Medical Association Ethics Review Committee (approval no. 2023-5). \u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eConsent for publication\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eAvailability of data and materials\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and/or analyzed during the current study are available from the corresponding author upon reasonable request.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eCompeting interests\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe author declare that they have no conflicts of interest.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eFunding\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo funding was received for conducting this study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eAuthor’s contributions\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eYN is the sole author of all parts of this manuscript. The author conceived this study, collected the data, performed the analysis, and drafted the manuscript. The author read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eAcknowledgements\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe would like to thank Yuto Honda, Yuko Matsuo, and Yukari Shimazaki for their cooperation in this study, conducted at a junior high school. We also thank Dr. Hideaki Kondo of the Department of General Medicine, Nagasaki University Hospital for his extensive guidance and advice on this study. We would like to express our deep appreciation for the cooperation of all those involved, including the students and their parents, who participated in this study.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eGe L, Guyatt G, Tian J, Pan B, Chang Y, Chen Y, et al. 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Sleep Med. 2017;30:204-9. doi: 10.1016/j.sleep.2016.10.014.\u003c/li\u003e\n\u003cli\u003ePer H, Gunay N, Ismailogullari S, Oztop DB, Gunay O. Determination of restless legs syndrome prevalence in children aged 13-16years in the provincial center of Kayseri. Brain Dev. 2017;39(2):154-60. doi: 10.1016/j.braindev.2016.08.011.\u003c/li\u003e\n\u003cli\u003eXue R, Liu G, Ma S, Yang J, Li L. An epidemiologic study of restless legs syndrome among Chinese children and adolescents. Neurol Sci. 2015;36(6):971-6. doi: 10.1007/s10072-015-2206-1.\u003c/li\u003e\n\u003cli\u003eTurkdogan D, Bekiroglu N, Zaimoglu S. A prevalence study of restless legs syndrome in Turkish children and adolescents. Sleep Med. 2011;12(4):315-21. doi: 10.1016/j.sleep.2010.08.013.\u003c/li\u003e\n\u003cli\u003ePicchietti D, Allen RP, Walters AS, Davidson JE, Myers A, Ferini-Strambi L. Restless legs syndrome: prevalence and impact in children and adolescents--the Peds REST study. Pediatrics. 2007;120(2):253-66. doi: 120/2/253 [pii] 10.1542/peds.2006-2767.\u003c/li\u003e\n\u003cli\u003ePartinen E, Inoue Y, Sieminski M, Merikanto I, Bjorvatn B, Bolstad CJ, et al. Restless legs symptoms increased during COVID-19 pandemic. International ICOSS-survey. Sleep Med. 2024;119:389-98. doi: 10.1016/j.sleep.2024.04.016.\u003c/li\u003e\n\u003cli\u003eWeinstock LB, Brook JB, Walters AS, Goris A, Afrin LB, Molderings GJ. Restless legs syndrome is associated with long-COVID in women. J Clin Sleep Med. 2022;18(5):1413-8. doi: 10.5664/jcsm.9898.\u003c/li\u003e\n\u003cli\u003eKim J, Kang KW, Kim KT, Cho YW. Prevalence of restless legs syndrome during the 2019 coronavirus disease pandemic in South Korea: A nationwide cross-sectional population-based study. Front Neurol. 2022;13:1101711. doi: 10.3389/fneur.2022.1101711.\u003c/li\u003e\n\u003cli\u003eYang L, Kim TW, Han Y, Nair MS, Harschnitz O, Zhu J, et al. SARS-CoV-2 infection causes dopaminergic neuron senescence. Cell Stem Cell. 2024;31(2):196-211.e6. doi: https://doi.org/10.1016/j.stem.2023.12.012.\u003c/li\u003e\n\u003cli\u003eOkajima I, Komada Y, Ito W, Inoue Y. Sleep Debt and Social Jetlag Associated with Sleepiness, Mood, and Work Performance among Workers in Japan. Int J Environ Res Public Health. 2021;18(6). doi: 10.3390/ijerph18062908.\u003c/li\u003e\n\u003cli\u003eIbata R, Takano Y, Machida N, Ubara A, Motoya R, Okajima I. Development and validation of the Japanese version of the Restorative Sleep Questionnaire in community samples. Sleep Med. 2023;108:45-52. doi: 10.1016/j.sleep.2023.05.015.\u003c/li\u003e\n\u003cli\u003eDrake CL, Hays RD, Morlock R, Wang F, Shikiar R, Frank L, et al. Development and evaluation of a measure to assess restorative sleep. J Clin Sleep Med. 2014;10(7):733-41, 41a-41e. doi: 10.5664/jcsm.3860.\u003c/li\u003e\n\u003cli\u003eOkajima I, Nakajima S, Kobayashi M, Inoue Y. Development and validation of the Japanese version of the Athens Insomnia Scale. Psychiatry Clin Neurosci. 2013;67(6):420-5. doi: 10.1111/pcn.12073.\u003c/li\u003e\n\u003cli\u003eSoldatos CR, Dikeos DG, Paparrigopoulos TJ. Athens Insomnia Scale: validation of an instrument based on ICD-10 criteria. J Psychosom Res. 2000;48(6):555-60. doi: 10.1016/s0022-3999(00)00095-7.\u003c/li\u003e\n\u003cli\u003eOkajima I, Miyamoto T, Ubara A, Omichi C, Matsuda A, Sumi Y, et al. Evaluation of Severity Levels of the Athens Insomnia Scale Based on the Criterion of Insomnia Severity Index. Int J Environ Res Public Health. 2020;17(23). doi: 10.3390/ijerph17238789.\u003c/li\u003e\n\u003cli\u003eFerri R, Lanuzza B, Cosentino FI, Iero I, Tripodi M, Spada RS, et al. A single question for the rapid screening of restless legs syndrome in the neurological clinical practice. Eur J Neurol. 2007;14(9):1016-21. doi: 10.1111/j.1468-1331.2007.01862.x.\u003c/li\u003e\n\u003cli\u003eMuramatsu K, Kamijima K, Yoshida M, Otsubo T, Miyaoka H, Muramatsu Y, et al. The patient health questionnaire, Japanese version: Validity according to the mini-international neuropsychiatry interview-plus. Psychological Reports. 2007;101(3 I):952-60. doi: 10.2466/PR0.101.3.952-960.\u003c/li\u003e\n\u003cli\u003eKroenke K, Spitzer RL, Williams JBW. The PHQ-9: Validity of a brief depression severity measure. Journal of General Internal Medicine. 2001;16(9):606-13. doi: 10.1046/j.1525-1497.2001.016009606.x.\u003c/li\u003e\n\u003cli\u003eSpitzer RL, Kroenke K, Williams JB, L\u0026ouml;we B. A brief measure for assessing generalized anxiety disorder: the GAD-7. Arch Intern Med. 2006;166(10):1092-7. doi: 10.1001/archinte.166.10.1092.\u003c/li\u003e\n\u003cli\u003eIgarashi T. Development of the Japanese version of the three-item loneliness scale. BMC Psychology. 2019;7(1):20. doi: 10.1186/s40359-019-0285-0.\u003c/li\u003e\n\u003cli\u003eHughes ME, Waite LJ, Hawkley LC, Cacioppo JT. A Short Scale for Measuring Loneliness in Large Surveys: Results From Two Population-Based Studies. Research on Aging. 2004;26(6):655-72. doi: 10.1177/0164027504268574.\u003c/li\u003e\n\u003cli\u003eKurimoto A, Awata S, Ohkubo T, Tsubota-Utsugi M, Asayama K, Takahashi K, et al. [Reliability and validity of the Japanese version of the abbreviated Lubben Social Network Scale]. Nihon Ronen Igakkai Zasshi. 2011;48(2):149-57. doi: 10.3143/geriatrics.48.149.\u003c/li\u003e\n\u003cli\u003eLubben J, Blozik E, Gillmann G, Iliffe S, von Renteln Kruse W, Beck JC, et al. Performance of an abbreviated version of the Lubben Social Network Scale among three European community-dwelling older adult populations. Gerontologist. 2006;46(4):503-13. doi: 10.1093/geront/46.4.503.\u003c/li\u003e\n\u003cli\u003eKanda Y. Investigation of the freely available easy-to-use software \u0026lsquo;EZR\u0026rsquo; for medical statistics. Bone marrow transplantation. 2013;48(3):452-8. doi: 10.1038/bmt.2012.244.\u003c/li\u003e\n\u003cli\u003eArakawa M, Taira K, Tanaka H, Yamakawa K, Toguchi H, Kadekaru H, et al. A survey of junior high school students\u0026apos; sleep habit and lifestyle in Okinawa. Psychiatry Clin Neurosci. 2001;55(3):211-2. doi: 10.1046/j.1440-1819.2001.00829.x.\u003c/li\u003e\n\u003cli\u003eJohnson JG, Harris ES, Spitzer RL, Williams JBW. The patient health questionnaire for adolescents: Validation of an instrument for the assessment of mental disorders among adolescent primary care patients. Journal of Adolescent Health. 2002;30(3):196-204. doi: https://doi.org/10.1016/S1054-139X(01)00333-0.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003eTable 1. Demographic characteristics\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"284\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 208px;\"\u003e\n \u003cp\u003en\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e392\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 208px;\"\u003e\n \u003cp\u003eGrade\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 208px;\"\u003e\n \u003cp\u003e\u0026nbsp; seventh, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e122 (31.1)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 208px;\"\u003e\n \u003cp\u003e\u0026nbsp; eighth, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e143 (36.5)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 208px;\"\u003e\n \u003cp\u003e\u0026nbsp; ninth, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e127 (32.4)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 208px;\"\u003e\n \u003cp\u003eElectronic devices user, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e257 (65.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 208px;\"\u003e\n \u003cp\u003eLast electronic devices usage time\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e257 (65.6)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 208px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026lt; 21:00, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e\u0026nbsp;59 (15.1)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 208px;\"\u003e\n \u003cp\u003e\u0026nbsp; 21:00\u0026ndash;22:00, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e\u0026nbsp;76 (19.4)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 208px;\"\u003e\n \u003cp\u003e\u0026nbsp; 22:00\u0026ndash;23:00, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e128 (32.7)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 208px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026ge; 23:00, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e129 (32.9)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 208px;\"\u003e\n \u003cp\u003ePast history of COVID-19, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e296 (75.5)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 208px;\"\u003e\n \u003cp\u003eCOVID-19 unvaccinated person,\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e195 (49.7)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eCOVID-19: coronavirus disease\u003c/p\u003e\n\u003cp\u003eTable 2. Comparisons of demographic and psychosomatic symptoms between restorative sleep (RS) group and nonrestorative sleep (NRS) group\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"565\"\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 243px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003eRS group\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 127px;\"\u003e\n \u003cp\u003eNRS group\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e\u003cem\u003eP\u003c/em\u003e value\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 243px;\"\u003e\n \u003cp\u003en\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e273\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 127px;\"\u003e\n \u003cp\u003e119\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e392\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 243px;\"\u003e\n \u003cp\u003eMale, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e137 (50.2)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 127px;\"\u003e\n \u003cp\u003e\u0026nbsp;48 (40.3)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e0.08\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 243px;\"\u003e\n \u003cp\u003eGrade\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 127px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 243px;\"\u003e\n \u003cp\u003e\u0026nbsp; seventh, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;89 (32.6)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 127px;\"\u003e\n \u003cp\u003e\u0026nbsp;33 (27.7)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e0.52\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 243px;\"\u003e\n \u003cp\u003e\u0026nbsp; eighth, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e100 (36.6)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 127px;\"\u003e\n \u003cp\u003e\u0026nbsp;43 (36.1)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 243px;\"\u003e\n \u003cp\u003e\u0026nbsp; ninth, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;84 (30.8)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 127px;\"\u003e\n \u003cp\u003e\u0026nbsp;43 (36.1)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 243px;\"\u003e\n \u003cp\u003eElectronic devices user, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e169 (61.9)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 127px;\"\u003e\n \u003cp\u003e\u0026nbsp;88 (73.9)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e0.02\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 243px;\"\u003e\n \u003cp\u003eLast electronic devices usage time\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 127px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 243px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026lt; 21:00, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;44 (16.1)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 127px;\"\u003e\n \u003cp\u003e\u0026nbsp;15 (12.6)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e0.006\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 243px;\"\u003e\n \u003cp\u003e\u0026nbsp; 21:00\u0026ndash;22:00, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;60 (22.0)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 127px;\"\u003e\n \u003cp\u003e\u0026nbsp;16 (13.4)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 243px;\"\u003e\n \u003cp\u003e\u0026nbsp; 22:00\u0026ndash;23:00, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;94 (34.4)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 127px;\"\u003e\n \u003cp\u003e\u0026nbsp;34 (28.6)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 243px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026ge; 23:00, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;75 (27.5)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 127px;\"\u003e\n \u003cp\u003e\u0026nbsp;54 (45.4)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 243px;\"\u003e\n \u003cp\u003eHeadache, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;74 (31.6)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 127px;\"\u003e\n \u003cp\u003e\u0026nbsp;60 (59.4)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 243px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026ge; 2 days/week, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;19 (7.0)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 127px;\"\u003e\n \u003cp\u003e\u0026nbsp;32 (26.9)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 243px;\"\u003e\n \u003cp\u003eAbdominal pain, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;76 (27.8)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 127px;\"\u003e\n \u003cp\u003e\u0026nbsp;61 (51.3)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 243px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;\u0026ge; 2 days/week, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;25 (9.2)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 127px;\"\u003e\n \u003cp\u003e\u0026nbsp;23 (19.3)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e0.007\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 243px;\"\u003e\n \u003cp\u003eAppetite loss, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;38 (13.9)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 127px;\"\u003e\n \u003cp\u003e\u0026nbsp;40 (33.6)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 243px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;\u0026ge; 2 days/week, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;13 (4.8)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 127px;\"\u003e\n \u003cp\u003e\u0026nbsp;18 (15.1)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 243px;\"\u003e\n \u003cp\u003eFatiguability, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e148 (54.2)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 127px;\"\u003e\n \u003cp\u003e103 (86.6)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 243px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;\u0026ge; 2 days/week, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;71 (26.0)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 127px;\"\u003e\n \u003cp\u003e\u0026nbsp;73 (61.3)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 243px;\"\u003e\n \u003cp\u003ePast history of COVID-19, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e206 (75.5)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 127px;\"\u003e\n \u003cp\u003e\u0026nbsp;90 (75.6)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 243px;\"\u003e\n \u003cp\u003eCOVID-19 unvaccinated person, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e135 (49.5)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 127px;\"\u003e\n \u003cp\u003e\u0026nbsp;60 (50.4)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e0.10\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 243px;\"\u003e\n \u003cp\u003ePHQ-9 score, median (IQR)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;1.0 (0.0, 4.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 127px;\"\u003e\n \u003cp\u003e\u0026nbsp;5.0 (2.0, 9.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 243px;\"\u003e\n \u003cp\u003e\u0026nbsp; PHQ-9 score \u0026ge; 5, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;50 (18.3)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 127px;\"\u003e\n \u003cp\u003e\u0026nbsp;62 (52.1)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 243px;\"\u003e\n \u003cp\u003eGAD-7 score, median (IQR)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;1.0 (0.0, 4.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 127px;\"\u003e\n \u003cp\u003e\u0026nbsp;1.0 (0.0, 3.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e0.71\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 243px;\"\u003e\n \u003cp\u003e\u0026nbsp;GAD-7 score \u0026ge; 5, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;51 (18.7)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 127px;\"\u003e\n \u003cp\u003e\u0026nbsp;23 (19.3)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e0.89\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 243px;\"\u003e\n \u003cp\u003eLoneliness scale score, median (IQR)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;3.0 (3.0, 4.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 127px;\"\u003e\n \u003cp\u003e\u0026nbsp;3.0 (3.0, 4.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e0.60\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 243px;\"\u003e\n \u003cp\u003e\u0026nbsp;Loneliness scale score \u0026ge; 6, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;27 (9.9)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 127px;\"\u003e\n \u003cp\u003e\u0026nbsp; 7 (5.9)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e0.24\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 243px;\"\u003e\n \u003cp\u003eLSNS-6 score, median (IQR)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e21.0 (16.0, 24.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 127px;\"\u003e\n \u003cp\u003e21.0 (17.0, 26.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e0.22\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 243px;\"\u003e\n \u003cp\u003e\u0026nbsp;LSNS-6 score \u0026ge; 12, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;32 (11.7)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 127px;\"\u003e\n \u003cp\u003e\u0026nbsp; 8 (6.7)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e0.15\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eIQR: Interquartile range, GAD: Generalized Anxiety Disorder, LSNS-6: Lubben Social Network Scale-6, NRS: nonrestorative sleep, PHQ: Patient Health Questionnaire, RS: Restorative sleep, RSQ: Restorative Sleep Questionnaire.\u003c/p\u003e\n\u003cp\u003eTable 3. Comparisons of sleep characteristics between restorative sleep (RS) group and nonrestorative sleep (NRS) group\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"624\"\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 284px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003eRS group\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 134px;\"\u003e\n \u003cp\u003eNRS group\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e\u003cem\u003eP\u003c/em\u003e value\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 284px;\"\u003e\n \u003cp\u003en\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e273\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 134px;\"\u003e\n \u003cp\u003e119\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e392\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 284px;\"\u003e\n \u003cp\u003eAIS score, median (IQR)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;2.0 (1.0, 4.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 134px;\"\u003e\n \u003cp\u003e\u0026nbsp;4.0 (2.0, 6.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 284px;\"\u003e\n \u003cp\u003e\u0026nbsp;AIS score \u0026ge; 6, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;31 (11.4)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 134px;\"\u003e\n \u003cp\u003e\u0026nbsp;35 (29.4)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 284px;\"\u003e\n \u003cp\u003eRSQ score, median (IQR)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e65.6 (56.3, 78.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 134px;\"\u003e\n \u003cp\u003e37.5 (31.3, 40.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 284px;\"\u003e\n \u003cp\u003eDifficulty getting up, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;44 (16.1)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 134px;\"\u003e\n \u003cp\u003e\u0026nbsp;48 (40.3)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 284px;\"\u003e\n \u003cp\u003eRLS symptoms, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;30 (11.0)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 134px;\"\u003e\n \u003cp\u003e\u0026nbsp;32 (26.9)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 284px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026ge; 2 days/week, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;13 (4.8)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 134px;\"\u003e\n \u003cp\u003e\u0026nbsp;17 (14.3)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e0.003\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 284px;\"\u003e\n \u003cp\u003eAverage sleep duration h, median (IQR)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;8.00 (7.50, 8.57)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 134px;\"\u003e\n \u003cp\u003e\u0026nbsp;7.79 (7.04, 8.39)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e0.01\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 284px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026lt; 7 hours, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;33 (12.1)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 134px;\"\u003e\n \u003cp\u003e\u0026nbsp;29 (24.4)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e0.02\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 284px;\"\u003e\n \u003cp\u003e\u0026nbsp; 7\u0026ndash;8 hours, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;88 (32.2)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 134px;\"\u003e\n \u003cp\u003e\u0026nbsp;39 (32.8)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 284px;\"\u003e\n \u003cp\u003e\u0026nbsp; 8\u0026ndash;9 hours, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e112 (41.0)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 134px;\"\u003e\n \u003cp\u003e\u0026nbsp;39 (32.8)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 284px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026ge; 9 hours, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;40 (14.7)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 134px;\"\u003e\n \u003cp\u003e\u0026nbsp;12 (10.1)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 284px;\"\u003e\n \u003cp\u003eIdeal sleep duration h, median (IQR)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e9.00 (8.00, 10.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 134px;\"\u003e\n \u003cp\u003e9.00 (8.00, 10.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e0.31\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 284px;\"\u003e\n \u003cp\u003eWeekday sleep habits\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 134px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 284px;\"\u003e\n \u003cp\u003e\u0026nbsp; Sleep duration h, median (IQR)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;8.00 (7.00, 8.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 134px;\"\u003e\n \u003cp\u003e\u0026nbsp;7.50 (6.50, 8.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e0.006\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 284px;\"\u003e\n \u003cp\u003e\u0026nbsp; Falling asleep time, h:mm, median (IQR)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e22:50 (22:00, 23:30)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 134px;\"\u003e\n \u003cp\u003e23:00 (22:35, 23:30)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 284px;\"\u003e\n \u003cp\u003e\u0026nbsp; Last waking up time, h:mm, median (IQR)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e6:30 (6:30, 7:00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 134px;\"\u003e\n \u003cp\u003e6:40 (6:25, 7:00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e0.84\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 284px;\"\u003e\n \u003cp\u003eWeekday sleep habits\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 134px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 284px;\"\u003e\n \u003cp\u003e\u0026nbsp; Sleep duration h, median (IQR)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;8.50 (8.00, 10.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 134px;\"\u003e\n \u003cp\u003e\u0026nbsp;9.00 (8.00, 10.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e0.98\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 284px;\"\u003e\n \u003cp\u003e\u0026nbsp; Falling asleep time, h:mm, median (IQR)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e23:00 (22:30, 23:30)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 134px;\"\u003e\n \u003cp\u003e23:30 (23:00, 0:00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 284px;\"\u003e\n \u003cp\u003e\u0026nbsp; Last waking up time, h:mm, median (IQR)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e8:00 (7:00, 9:00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 134px;\"\u003e\n \u003cp\u003e8:30 (7:30, 9:45)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 284px;\"\u003e\n \u003cp\u003eCorrected mid-sleep time, h:mm, median (IQR)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e3:09 (2:38, 3:33)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 134px;\"\u003e\n \u003cp\u003e3:29 (3:03, 4:17)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 284px;\"\u003e\n \u003cp\u003eChronotype\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 134px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 284px;\"\u003e\n \u003cp\u003e Morning type\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e106 (38.8)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 134px;\"\u003e\n \u003cp\u003e\u0026nbsp;25 (21.0)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 284px;\"\u003e\n \u003cp\u003e Intermediate type\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;95 (34.8)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 134px;\"\u003e\n \u003cp\u003e\u0026nbsp;36 (30.3)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 284px;\"\u003e\n \u003cp\u003e Evening type\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;72 (26.4)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 134px;\"\u003e\n \u003cp\u003e\u0026nbsp;58 (48.7)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 284px;\"\u003e\n \u003cp\u003eWeekly sleep loss, h, median (IQR)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;1.43 (0.71, 2.86)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 134px;\"\u003e\n \u003cp\u003e\u0026nbsp;2.14 (1.43, 2.86)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e0.007\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 284px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026lt; 1 hour, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e168 (61.5)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 134px;\"\u003e\n \u003cp\u003e\u0026nbsp;53 (44.5)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e0.007\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 284px;\"\u003e\n \u003cp\u003e\u0026nbsp; 1\u0026ndash;2 hours, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;72 (26.4)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 134px;\"\u003e\n \u003cp\u003e\u0026nbsp;46 (38.7)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 284px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026ge; 2 hours, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;33 (12.1)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 134px;\"\u003e\n \u003cp\u003e\u0026nbsp;20 (16.8)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 284px;\"\u003e\n \u003cp\u003eSJL, mm, median (IQR)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e57.5 (30.0, 80.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 134px;\"\u003e\n \u003cp\u003e75.0 (37.5, 123.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eAIS: Athens Insomnia Scale, IQR: Interquartile range, RLS: restless legs syndrome, RSQ: Restorative Sleep Questionnaire, SJL: social Jetlag.\u003c/p\u003e\n\u003cp\u003eTable 4. Logistic regression analysis for nonrestorative sleep\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 199px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 183px;\"\u003e\n \u003cp\u003eUnivariable analysis\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 186px;\"\u003e\n \u003cp\u003eMultivariable analysis*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 199px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 183px;\"\u003e\n \u003cp\u003eOdds ratio (95% CI)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 186px;\"\u003e\n \u003cp\u003eOdds ratio (95% CI)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 199px;\"\u003e\n \u003cp\u003eAverage total sleep time\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 183px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 186px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 199px;\"\u003e\n \u003cp\u003e \u0026lt; 7 hr\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 183px;\"\u003e\n \u003cp\u003e2.52 (1.36-4.68)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 186px;\"\u003e\n \u003cp\u003e1.53 (0.76-3.09)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 199px;\"\u003e\n \u003cp\u003e 7\u0026ndash;8 hr\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 183px;\"\u003e\n \u003cp\u003e1.27 (0.75-2.15)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 186px;\"\u003e\n \u003cp\u003e0.91 (0.51-1.65)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 199px;\"\u003e\n \u003cp\u003e 8\u0026ndash;9 hr\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 183px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 186px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 199px;\"\u003e\n \u003cp\u003e \u0026ge; 9 hr\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 183px;\"\u003e\n \u003cp\u003e0.86 (0.41-1.81)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 186px;\"\u003e\n \u003cp\u003e0.68 (0.30-1.57)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 199px;\"\u003e\n \u003cp\u003eAthens Insomnia Scale score\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 183px;\"\u003e\n \u003cp\u003e3.25 (1.89-5.60)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 186px;\"\u003e\n \u003cp\u003e1.92 (1.03-3.57)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 199px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026lt; 6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 183px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 186px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 199px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026ge; 6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 183px;\"\u003e\n \u003cp\u003e3.25 (1.89-5.60)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 186px;\"\u003e\n \u003cp\u003e1.92 (1.03-3.57)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 199px;\"\u003e\n \u003cp\u003eChronotype\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 183px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 186px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 199px;\"\u003e\n \u003cp\u003e Morning type\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 183px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 186px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 199px;\"\u003e\n \u003cp\u003e Intermediate type\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 183px;\"\u003e\n \u003cp\u003e1.61 (0.90-2.87)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 186px;\"\u003e\n \u003cp\u003e1.54 (0.81-2.90)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 199px;\"\u003e\n \u003cp\u003e Evening type\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 183px;\"\u003e\n \u003cp\u003e3.42 (1.96-5.96)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 186px;\"\u003e\n \u003cp\u003e3.00 (1.62-5.56)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 199px;\"\u003e\n \u003cp\u003eRLS symptoms\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 183px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 186px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 199px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026lt; 2 days/week or symptom-free\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 183px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 186px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 199px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026ge; 2 days/week\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 183px;\"\u003e\n \u003cp\u003e2.98 (1.71-5.19)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 186px;\"\u003e\n \u003cp\u003e2.75 (1.12-6.76)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 199px;\"\u003e\n \u003cp\u003ePHQ-9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 183px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 186px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 199px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026lt; 5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 183px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 186px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 199px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026ge; 5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 183px;\"\u003e\n \u003cp\u003e4.85 (3.02-7.78)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 186px;\"\u003e\n \u003cp\u003e3.77 (2.24-6.34)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e*Adjusted for sex, grade, and past history of COVID-19. CI: confidence interval, PHQ: Patient Health Questionnaire, RLS: restless legs syndrome.\u0026nbsp;\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"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":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"chronotype, depression, insomnia, nonrestorative sleep, restless legs syndrome, restorative sleep, sleep duration","lastPublishedDoi":"10.21203/rs.3.rs-6472923/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6472923/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eStudy objectives\u003c/h2\u003e \u003cp\u003eNonrestorative sleep (NRS) has been identified as a potential risk factor for physical and mental well-being in adults, but limited research exists for children and adolescents. This study aimed to clarify the factors affecting NRS in Japanese junior high school students.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eThe participants were 529 Japanese junior high school students in grades 7 through 9. Participants were asked to respond to Google Forms, and responses were obtained from 392 students. Sleep habits, history of coronavirus disease (COVID-19), physical symptoms, depressive and symptoms, social isolation, insomnia symptoms, and the presence of symptoms of restless legs syndrome (RLS) were identified. NRS was evaluated using the Restorative Sleep Questionnaire, with scores below 48.5 categorizing participants into the NRS group. Logistic regression analysis was conducted to explore the relationship between NRS and various factors, including sleep duration, insomnia symptoms, RLS symptoms, chronotype, and depressive symptoms.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eThe NRS group comprised 30.4% of participants and exhibited a higher prevalence of physical and depressive symptoms compared to those with restorative sleep. Logistic regression analysis, adjusted for sex, grade, and COVID-19 history, revealed the following odds ratios (95% confidence intervals) for NRS: depressive symptoms 3.77 (2.24\u0026ndash;6.34), evening chronotype 3.00 (1.62\u0026ndash;5.56), RLS symptoms 2.75 (1.12\u0026ndash;6.76), and insomnia symptoms 1.92 (1.03\u0026ndash;3.57).\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003eThese findings suggest that NRS in Japanese junior high school students is associated with physical and mental health issues. When considering health problems in this population, measures are needed to address the sleep-wake problems associated with NRS.\u003c/p\u003e","manuscriptTitle":"Nonrestorative Sleep is Associated with Somatic and Depressive Symptoms in Japanese Junior High School Students","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-05-06 16:09:20","doi":"10.21203/rs.3.rs-6472923/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"b08edd38-5253-4180-84b9-28f7ab8bf719","owner":[],"postedDate":"May 6th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-11-17T16:00:23+00:00","versionOfRecord":{"articleIdentity":"rs-6472923","link":"https://doi.org/10.1186/s40101-025-00412-8","journal":{"identity":"journal-of-physiological-anthropology","isVorOnly":false,"title":"Journal of Physiological Anthropology"},"publishedOn":"2025-11-11 15:56:55","publishedOnDateReadable":"November 11th, 2025"},"versionCreatedAt":"2025-05-06 16:09:20","video":"","vorDoi":"10.1186/s40101-025-00412-8","vorDoiUrl":"https://doi.org/10.1186/s40101-025-00412-8","workflowStages":[]},"version":"v1","identity":"rs-6472923","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6472923","identity":"rs-6472923","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}