Paradoxical Insomnia Versus Atypical Obstructive Sleep Apnea or Mixed Disorder? Case Report and Literature Review.

A 69‐year‐old female with a long‐standing history of sleep disturbances presented for a somnology evaluation. Her medical history includes irritable bowel syndrome and a hysterectomy performed 12 years ago for endometriosis. The patient reported experiencing sleep problems since adolescence, which have progressively worsened over the past 15 years. She described her main complaints as difficulty falling asleep and fragmented sleep. Regarding her pharmacological history, the patient reported daily use of clonazepam 2 mg for approximately 10 years. She also mentioned prior psychiatric evaluations and treatment with medications such as mirtazapine, quetiapine, and escitalopram, all of which yielded unsatisfactory results and caused adverse effects, including nightmares. At the time of the initial evaluation, she described a typical sleep pattern of going to bed at 9:00 p.m., with highly variable sleep latency ranging from several hours to not falling asleep at all. When she did manage to fall asleep, she experienced sleep fragmentation 3–4 times per night, followed by difficulty returning to sleep. She denied a history of snoring, apnea, restless legs syndrome, or parasomnias and reported no significant daytime sleepiness or fatigue. Clinical scales and laboratory results are summarized in Table  1 . Clinical scales and laboratory tests at initial assessment. In terms of sleep hygiene, the patient stated that she slept in a dark room, avoided using her cell phone for 1 h before bedtime (though she occasionally used it afterward), and listened to relaxing music to help her fall asleep.

Alden Xavier Haslam: conceptualization, investigation, methodology, project administration, supervision, validation, visualization, writing – original draft, writing – review and editing. Adrián Coulson Romero: conceptualization, investigation, supervision, validation, writing – review and editing. Camila Angélica Espinoza Torrez: conceptualization, validation, writing – original draft, writing – review and editing. Manuel Ampié Espinoza: conceptualization, validation, writing – original draft, writing – review and editing.

At the follow‐up appointment, the patient expressed dissatisfaction with the study results and reported no improvement with the amitriptyline treatment, leading her to discontinue follow‐up. Regarding cognitive behavioral therapy (CBT), the patient completed eight sessions. The psychologist noted poor adherence to CBT techniques despite her attendance. A significant observation was that when the patient was provided with an informational pamphlet on paradoxical insomnia, she declined to read it and remained resistant to the diagnosis. An anxiety disorder was added to her diagnosis during this period. By the end of the sessions, some improvement was observed, and a gradual reduction in benzodiazepine use was successfully achieved. The current ICSD‐3 does not retain paradoxical insomnia as an independent diagnosis but discusses it under chronic insomnia disorder, particularly in cases of sleep state misperception. According to ICSD‐3, the diagnosis of chronic insomnia requires: difficulty initiating or maintaining sleep, or early‐morning awakening; symptoms occurring at least three times per week; duration of at least 3 months; associated daytime impairment. difficulty initiating or maintaining sleep, or early‐morning awakening; symptoms occurring at least three times per week; duration of at least 3 months; associated daytime impairment. In paradoxical insomnia, however, patients often meet the first three criteria but lack objective impairment. Our patient met all the ICSD‐3 insomnia criteria except for significant daytime dysfunction, which is a hallmark of paradoxical insomnia. Moreover, there was a clear discrepancy between her subjective report of very poor sleep and objective findings: PSG revealed 329 min of sleep with 77.1% efficiency, and actigraphy demonstrated consistent sleep durations across the week. Despite this, the patient perceived that she did not sleep during the PSG night, fulfilling the definition of sleep state misperception.

Paradoxical insomnia, previously known as pseudo‐insomnia or sleep state misperception, is described as a severe complaint of sleep disturbance without objective evidence to support it. Patients with paradoxical insomnia often underestimate the amount of time they sleep, perceiving sleep time as wakefulness [ 3 ]. As a result, individuals with paradoxical insomnia typically do not experience symptoms of daytime sleepiness. The etiology of paradoxical insomnia is not fully understood, though several hypotheses have been proposed. First, certain personality traits, such as hysteria, hypochondriasis, paranoia, hypomania, and psychasthenia, have been associated with paradoxical insomnia [ 6 ]. Additionally, higher levels of depression and anxiety have been observed in these patients [ 7 ]. Structural changes in the brain have also been suggested, including alterations in the caudate nucleus, hippocampus, thalamus, amygdala, putamen, and nucleus accumbens. These structural changes may be related to mechanisms of sleep, sleep perception, and other subjective and objective sleep symptoms [ 8 ]. Electroencephalographic changes have been identified in patients with paradoxical insomnia, such as a higher percentage of cyclic alternating patterns [ 9 ], increased alpha, sigma, and beta activity, reduced delta activity during non‐REM stages [ 10 ], and changes during REM sleep [ 11 ]. These findings may help explain the poor perception of sleep, frequent awakenings, and hyperarousal seen in these patients, suggesting a possible neurobiological component to paradoxical insomnia. In paradoxical insomnia, the coexistence of other sleep disorders should be considered, such as OSA. Given that 40%–60% of patients with OSA report symptoms of insomnia and that erroneous sleep perception is common in this population [ 12 ], OSA patients may be at risk of developing paradoxical insomnia, complicating their management. Other conditions, such as periodic limb movement disorder, restless legs syndrome, circadian rhythm disorders, and parasomnias, should also be considered and ruled out. Regarding diagnosis, no established consensus exists. Based on the literature, the diagnosis is primarily clinical. Initially, polysomnography or actigraphy was deemed unnecessary, particularly in cases where the patient's report of not sleeping was physiologically impossible [ 13 ]. However, in many cases, objective evidence of sleep is required for an accurate diagnosis, with actigraphy being particularly useful. Although the ICSD‐2 criteria are now outdated, polysomnographic criteria include 6 h of sleep and > 85% sleep efficiency, along with additional criteria such as a ≥ 60‐min discrepancy between subjective and objective sleep perception [ 14 ]. As for treatment, high‐quality evidence is lacking, though some pharmacological options have been explored. A clinical trial found that olanzapine and risperidone improved sleep quality in patients with paradoxical insomnia, with a greater effect observed for olanzapine [ 15 ]. Benzodiazepines may be considered for short‐term use, but their chronic use is associated with increased nocturnal awakenings and altered sleep architecture [ 16 ], along with high dependency rates and tolerance effects. Consequently, benzodiazepine analogs may be preferred. Non‐pharmacological therapies, such as cognitive‐behavioral therapy for insomnia (CBT‐I), should also be considered, as they may improve patients' sleep perception [ 17 ], although further studies are needed to evaluate their efficacy in this population. In our case, the patient presented with a mixed disorder of paradoxical insomnia and severe OSA. Interestingly, she displayed atypical characteristics, including a low STOP‐BANG score, the absence of hypertension, and a normal weight. It should be noted, however, that up to 20% of OSA cases occur in normal‐weight patients, with non‐anatomical factors implicated in up to 70% of cases. These include a low arousal threshold, unstable ventilatory control, and reduced effectiveness of upper airway dilator muscles during sleep. Anatomical contributors, such as subtle craniofacial abnormalities, may also play a role [ 18 ]. Although the AHI was elevated at 36.1/h, other parameters—such as a snoring index of 0 and CT90 of 0%—may seem inconsistent with typical obstructive sleep apnea. However, this paradox is increasingly recognized in atypical OSA phenotypes, especially among older adults and women. In our case, all respiratory events were classified as hypopneas, without apneas, and most were associated with EEG arousals rather than desaturations. The AHI was calculated according to AASM criteria, considering ≥ 30% airflow reduction with either ≥ 3% desaturation or an arousal. This pattern supports the diagnosis of OSA with a low arousal threshold and preserved oxygenation. These findings highlight the importance of recognizing non‐anatomical OSA variants, which may lack classic features such as snoring or hypoxemia. Similar cases have been reported in the literature, involving a patient with similar anthropometric features and low OSA risk. Despite resistance to multiple treatments, polysomnography revealed severe OSA (AHI 74.6/h), and OSA was ultimately attributed as the cause of her insomnia [ 19 ]. In conclusion, paradoxical insomnia is likely an underdiagnosed sleep disorder due to its clinical characteristics and patient profile. A limitation of this case is the lack of neuroimaging or cerebrospinal fluid analysis. Although the clinical evaluation did not suggest the presence of neurological or structural sleep disorders (such as narcolepsy, parasomnias of neurological origin, or neurodegeneration), we acknowledge that neuroimaging (e.g., MRI) could have provided further support to exclude underlying pathologies. The absence of neurological symptoms and normal neurocognitive performance contributed to the decision not to pursue such testing. Given the discrepancies in its definition and diagnosis, this condition can be misdiagnosed or coexist with other sleep disorders. It should be suspected in patients whose complaints of not sleeping do not align with the expected daytime repercussions, such as low scores on sleepiness scales. Additionally, it should be considered in patients with poor response to multiple treatments, affective disorders such as anxiety or depression, and even OSA.

Written informed consent was obtained from the patient(s) for the publication of this manuscript. All necessary precautions were taken to ensure the anonymity and confidentiality of the patient(s), and no identifying information has been included in the manuscript.

The initial management plan included amitriptyline 25 mg at night, melatonin 5 mg at night, gradual tapering of benzodiazepines, cognitive behavioral therapy, and sleep studies using polysomnography and actigraphy. Chronic insomnia of the paradoxical type was established as the initial working diagnosis. During the second evaluation, it was noted that the patient had not adhered to the prescribed treatment, citing fear that the medications might be addictive. However, she successfully reduced her benzodiazepine doses. The results of the polysomnography studies are presented in Table  2 . Polysomnography and actigraphy results. During the polysomnography, the technician noted that the patient reported feeling as though she had slept very little. However, the study findings indicated adequate sleep latency, acceptable sleep efficiency, and actigraphy results showing sufficient total sleep time on several days of the week, despite an increased number of awakenings. Based on these findings, the patient was diagnosed with chronic insomnia of the paradoxical subtype, along with severe obstructive sleep apnea (OSA).

Insomnia is one of the most prevalent sleep disorders, with a prevalence ranging from 5% to 50%, depending on the definition and context studied [ 1 ]. It often presents alongside multiple comorbidities, including depression, anxiety, substance abuse, dementia, and cardiovascular disease [ 2 ]. Among its subtypes is paradoxical insomnia, characterized by a misperception of sleep time without objective evidence to support this perception [ 3 ]. The prevalence of paradoxical insomnia ranges from 9.2% to 40.3% among patients with chronic insomnia [ 4 ]. This variability may stem from inconsistencies in the definitions of paradoxical insomnia. Historically, other terms have been used, such as pseudo‐insomnia, subjective insomnia, or sleep state misperception. The latter was introduced in 1997 by the 1st International Classification of Sleep Disorders (ICSD‐1), later redefined as paradoxical insomnia in the 2nd International Classification of Sleep Disorders (ICSD‐2), and subsequently removed, although it remains mentioned in the 3rd International Classification of Sleep Disorders (ICSD‐3) [ 5 ]. As a debated diagnosis, paradoxical insomnia may be overlooked during the evaluation of patients with sleep disorders. Here, we present the case of a patient with a chronic sleep disorder and prolonged benzodiazepine use, suggestive of paradoxical insomnia.

The authors declare no conflicts of interest.