The interaction between subclinical psychotic experiences, insomnia and objective measures of sleep

Association between non-restorative sleep and psychotic-like experiences among Chinese college students: A latent profile and moderated mediation analysis

BACKGROUND

Non-restorative sleep (NRS) is a core symptom of insomnia that has considerable consequences for daily life. However, the association between NRS and psychotic-like experiences (PLEs) remains unclear. The current study was designed to explore the relationship between NRS and PLEs as well as the mediation/moderation role of rumination and resilience among college students in China.

METHODS

3060 college students were recruited from two universities in South China from September 21st to October 26th, 2022. Non-restorative Sleep Scale, 8-item Positive Subscale of the Community Assessment of Psychic Experiences, Ruminative Response Scale, and 10-item Connor-Davidson Resilience Scale were administered. Latent profile analysis and moderated mediation analysis were performed.

RESULTS

11.3 % participants reported frequent PLEs in the past one month. Three profiles of rumination were identified and named as "low rumination" group (27.7 %), "medium rumination" group (55.3 %), and "high rumination" group (16.9 %). NRS directly predicted PLEs, and rumination played a significant mediation role between NRS and PLEs. Resilience significantly moderated the association between NRS and rumination as well as the association between NRS and PLEs.

CONCLUSIONS

NRS, rumination and resilience are important predictors to PLEs. Strategies on increasing restorative sleep, decreasing rumination, and enhancing resilience are of great significance in the prevention of PLEs.

Sleep Problems, Suicidal Ideation, and Psychopathology in First-Episode Psychosis

BACKGROUND AND HYPOTHESIS

Insomnia occurs frequently in the clinical course of schizophrenia. A growing literature has found associations between insomnia, suicidal ideation and behavior, and psychopathology in schizophrenia. We explored associations between sleep problems, suicidal ideation, and psychopathology in a cohort of patients with first-episode psychosis.

STUDY DESIGN

We performed a secondary analysis of data for n = 403 subjects with data from the Recovery After an Initial Schizophrenia Episode study using regression models.

STUDY RESULTS

The prevalence of sleep problems and suicidal ideation at baseline was 57% and 15%, respectively. After controlling for potential confounders, in the study baseline sleep problems were associated with increased odds of suicidal ideation with evidence of a dose-dependent relationship (OR = 2.25, 95% CI 1.15-4.41, P = .018). Over 24 months, sleep problems at any time point were associated with an over 3-fold increased odds of concurrent suicidal ideation (OR = 3.21, 95% CI 1.45-7.14, P = .004). Subjects with persistent sleep problems were almost 14 times more likely to endorse suicidal ideation at least once over the study than those without sleep problems (OR = 13.8, 95% CI 6.5-53.4, P < .001). Sleep problems were also a predictor of higher Positive and Negative Syndrome Scale total (β = 0.13-0.22), positive (β = 0.14-0.25), and general (β = 0.16-0.27) subscale scores at baseline and multiple follow-up visits (P < .01 for each).

CONCLUSIONS

Sleep problems are highly prevalent and associated with suicidal ideation and greater psychopathology in first-episode psychosis. Formal assessment and treatment of insomnia appear relevant to the clinical care of patients with psychosis as a predictor of suicidal ideation and symptom severity.

Schizophrenia and disruption of circadian rhythms: An overview of genetic, metabolic and clinical signs

A molecular clock in the suprachiasmatic nucleus of the anterior hypothalamus, which is entrained by the dark-light cycle and controls the sleep-wake cycle, regulates circadian rhythms. The risk of developing mental disorders, such as schizophrenia, has long been linked to sleep abnormalities. Additionally, a common aspect of mental disorders is sleep disturbance, which has a direct impact on the intensity of the symptoms and the quality of life of the patient. This relationship can be explained by gene alterations such as CLOCK in schizophrenia which are also important components of the physiological circadian rhythm. The function of dopamine and adenosine in circadian rhythm should also be noted, as these hypotheses are considered to be the most popular theories explaining schizophrenia pathogenesis. Therefore, determining the presence of a causal link between the two can be key to identifying new potential targets in schizophrenia therapy, which can open new avenues for clinical research as well as psychiatric care. We review circadian disruption in schizophrenia at the genetic, metabolic, and clinical levels. We summarize data about clock and clock-controlled genes' alterations, neurotransmitter systems' impairments, and association with chronotype in schizophrenia patients. Our findings demonstrate that in schizophrenia either homeostatic or circadian processes of sleep regulation are disturbed. Also, we found an insufficient number of studies aimed at studying the relationship between known biological phenomena of circadian disorders and clinical signs of schizophrenia.

The evolving role of quantitative actigraphy in clinical sleep medicine

Actigraphy has a consolidated role in Insomnia and Circadian Rhythm Sleep-Wake Disorders (CRSWD) and recent studies have highlighted the use of actigraphy for narcolepsy and REM sleep behaviour disorder (RBD). This review aims at summarising the results of studies published over the last decade regarding the use of actigraphy. Thirty-five studies proved eligible, and results were analysed separately for insomnia, narcolepsy and RBD. Actigraphy showed to consistently differentiate insomnia patients from healthy controls. Furthermore, the application of advanced analytical techniques has been shown to provide both unique insights into the physiology of insomnia and sleep misperception and to improve the specificity of actigraphy in detecting wakefulness within sleep periods. Regarding narcolepsy, several studies showed that actigraphy can detect peculiar sleep/wake disruption and the effects of pharmacological treatments. Finally, although the number of studies in RBD patients is still limited, the available evidence indicates a reduced amplitude of the activity pattern, sleep-wake rhythm dysregulation and daytime sleepiness. Therefore, the potential use of these markers as predictors of phenoconversion should be further explored. In conclusion, quantitative actigraphy presents a renewed interest when considering the possibility of using actigraphy in clinical sleep medicine to diagnose, monitor, and follow sleep disorders other than CRSWD.

Exploring the association between lifetime traumatic experiences and positive psychotic symptoms in a group of long-stay patients with schizophrenia: the mediating effect of depression, anxiety, and distress

BACKGROUND

Positive psychotic symptoms of schizophrenia are generally characterized by hallucinations and delusions. We propose to assess the relationship between total composite trauma and positive psychotic symptoms, along with the mediation effect of cognition, fear of COVID-19, insomnia, anxiety, distress, and depression of Lebanese patients with schizophrenia.

METHODS

A cross-sectional study was carried out, between June and July 2021, by deriving data from 155 long-stay in-patients diagnosed with schizophrenia.

RESULTS

Depression, anxiety, and distress but not cognitive impairment, insomnia, and fear of COVID-19) mediated the association between lifetime traumatic experiences and positive psychotic symptoms. Higher traumatic experiences were associated with greater depression, anxiety, and distress, indicating a significant positive total effect on positive psychotic scores. Moreover, higher depression, anxiety, and distress were significantly associated with higher positive psychotic symptoms.

CONCLUSION

Our results contribute to the existing knowledge by suggesting other possible intervention paths through mediating factors. Interventions that improve anxiety, depression, and distress severity may be effective in reducing positive psychotic symptoms among patients with schizophrenia having experienced lifetime trauma.

The Mind After Midnight: Nocturnal Wakefulness, Behavioral Dysregulation, and Psychopathology

Sufficient sleep with minimal interruption during the circadian/biological night supports daytime cognition and emotional regulation. Conversely, disrupted sleep involving significant nocturnal wakefulness leads to cognitive and behavioral dysregulation. Most studies to-date have examined how fragmented or insufficient sleep affects next-day functioning, but recent work highlights changes in cognition and behavior that occur when someone is awake during the night. This review summarizes the evidence for day-night alterations in maladaptive behaviors, including suicide, violent crime, and substance use, and examines how mood, reward processing, and executive function differ during nocturnal wakefulness. Based on this evidence, we propose the Mind after Midnight hypothesis in which attentional biases, negative affect, altered reward processing, and prefrontal disinhibition interact to promote behavioral dysregulation and psychiatric disorders.

The nature, consequences, mechanisms, and management of sleep disturbances in individuals at-risk for psychosis

There is strong evidence that sleep disturbances are commonly experienced by people with psychosis. Evidence has also shown that sleep disturbances are present since the very early stages of the disease, even during the pre-diagnostic phase. More recently, research involving young individuals at ultra-high risk (UHR) for psychosis documented frequent occurrence of sleep disturbances in this group. The very early onset of sleep disturbances in the course of psychosis has drawn attention to the possible links between sleep parameters and the risk of psychosis. To date, the nature of sleep disturbances characterizing the UHR stage remains unclear, with available studies having yielded mixed findings. In this regard, we performed this review to update the body of literature on the nature of sleep disturbances, their underlying mechanisms, their clinical and functional consequences, the prevention and intervention strategies in the at-risk for psychosis population. Our findings provided further support to the presence of disturbed sleep in UHR individuals as evidenced by subjective and objective sleep measures such as polysomnography, sleep electroencephalograms, and actigraphy. Reviewing the possible mechanisms underlying the relationship between sleep and psychosis emphasized its complex and multifactorial nature which is yet to be determined and understood. Further research is warranted to determine which facets of sleep disturbances are most detrimental to this specific population, and to what extent they can be causal factors or markers of psychosis.

Psychotic-Like Experiences Associated with Sleep Disturbance and Brain Volumes in Youth: Findings from the Adolescent Brain Cognitive Development Study

Background

Sleep disturbance is characteristic of schizophrenia and at-risk populations, suggesting a possible etiological role in psychosis. Biological mechanisms underlying associations between sleep and psychosis vulnerability are unclear, although reduced sleep-regulatory brain structure volumes are a proposed contributor. This study is the first to examine relationships between psychotic-like experiences (PLEs; subclinical symptoms reflecting psychosis vulnerability/risk), sleep, and brain volumes in youth.

Methods

Brain volumes of five sleep-related structures were examined in relation to PLEs and difficulties initiating and maintaining sleep (DIMS) in 9260 9-11 year-olds participating in the Adolescent Brain Cognitive Development (ABCD) study. Analytic models examined relationships between DIMS, PLEs, and brain volumes, as well as DIMS as a mediator of brain volume-PLEs relationships. Although sleep regulation structures (i.e., thalamus, basal forebrain, hypothalamus) were of primary interest, other potentially-relevant structures to sleep-related functioning and psychosis (i.e., hippocampus, amygdala) were also examined.

Results

PLEs were associated with increased DIMS as well as reduced volume in some, but not all, brain structures, including the thalamus and basal forebrain in children. DIMS was also associated with reduced left thalamus volume in youth. Increased DIMS partially, statistically mediated the relationship between left thalamic volume and PLEs, although the effect was relatively small.

Conclusions

Results highlight left thalamic volume as a potential neural mechanism underlying sleep disturbances and PLEs in childhood. Future studies should assess causal relationships between sleep, PLEs, and brain structure across adolescent development, interactions with other psychosis risk factors, and the role of sleep interventions in prevention of psychosis and a range of psychiatric conditions across the lifespan.

Comparison of actigraphy indices among patients with depression and schizophrenia: A preliminary study

Background:

Schizophrenia (SCZ) and depression (MDD) are associated with changes in sleep and activity patterns. However, because of a lack of objective evaluation, the diagnostic or clinical value of these sleep-activity patterns is unknown. In this study, we attempted to assess and compare the sleep and activity patterns using actigraphy.

Materials and Methods:

We have recruited 35 patients with SCZ (mean age: 29.29 ± 7.54 years) and 42 patients with MDD (mean age: 27.5 ± 5.59 years) in this cross-sectional study. The actigraphy indices [Time in bed (minutes), Onset latency (minutes), Total sleep time (Minutes), Sleep efficiency (%), WASO (minutes), number of awakening, and activity duration (minutes) were compared among the two groups using unpaired t-test and Fisher exact test.

Results:

In the MDD group, the time in bed (minutes) was significantly higher than in the SCZ group (402.7 ± 41.97 vs. 379.1 ± 40.45, P = 0.01), while the sleep efficiency was lower in the SCZ group than in the MDD group (60.04 ± 9.25 vs. 65.05 ± 7.16, P = 0.0092). An increase in onset latency (minutes) was observed in the SCZ group compared to the MDD group (49.06 ± 16.09 vs. 43.6 ± 10.14, P = 0.074). The difference in WASO (minutes), the number of awakenings, and activity duration (minutes) among the two groups were insignificant.

Conclusion:

Actigraphy parameters such as sleep efficiency and time in bed may be a useful sleep process, etiological, and prognostic markers in patients with SCZ and MDD. The longitudinal studies are needed to estimate the predictive role of these parameters for therapeutic outcome in these patients.

Do environmental risk factors for the development of psychosis distribute differently across dimensionally assessed psychotic experiences?

Psychotic experiences (PE) are associated with poorer functioning, higher distress and the onset of serious mental illness. Environmental exposures (e.g. childhood abuse) are associated with the development of PE. However, which specific exposures convey risk for each type or dimension of PE has rarely been explored. The Oxford Wellbeing Life and Sleep (OWLS) survey includes 22 environmental risk factors for psychosis and was designed to examine how environmental risks are associated with specific dimensions of PE. Multivariate logistic regression models were fit using these risk factors to predict six dimensions of PE (perceptual abnormalities, persecutory ideation, bizarre ideas, cognitive disorganisation, delusional mood and negative symptoms). Models were built using only 70% of the data, and then fit to the remaining data to assess their generalisability and quality. 1789 (27.2% men; mean age = 27.6; SD = 10.9) survey responses were analysed. The risk factors predictive of the most PE were anxiety, social withdrawal during childhood and trauma. Cannabis and depression predicted three dimensions with both predicting bizarre ideas and persecutory ideation. Psychological abuse and sleep quality each predicted two dimensions (persecutory ideation and delusional mood). Risk factors predicting one PE dimension were age (predicting cognitive disorganisation), physical abuse (bizarre ideas), bullying and gender (persecutory ideation); and circadian phase (delusional mood). These results lend support for a continuum of psychosis, suggesting environmental risks for psychotic disorders also increase the risk of assorted dimensions of PE. Furthermore, it advocates the use of dimensional approaches when examining environmental exposures for PE given that environmental risks distribute differently across dimensions.

Sleep disturbances and the At Risk Mental State: A systematic review and meta-analysis

AIMS

To synthesise and investigate how sleep disturbances relate to psychotic symptoms, functioning and Quality of Life (QoL) in At Risk Mental State (ARMS) youth.

METHOD

A comprehensive search of six databases (MEDLINE, PsycINFO, Embase, CINAHL, Web of Science and CENTRAL) was conducted. Eligible studies provided data on sleep disturbances or disorders in ARMS patients.

RESULTS

Sixteen studies met the inclusion criteria (n = 1962 ARMS patients) including 7 cross-sectional studies, 2 RCT's and 7 cohort studies. Narrative synthesis revealed that self-reported sleep (e.g., general disturbances, fragmented night time sleep and nightmares) was poorer among ARMS patients compared to healthy controls. In the limited studies (n = 4) including objective measurements of sleep disturbances, ARMS patients experienced higher levels of movement during sleep, more daytime naps and increased sleep latency compared to controls. Furthermore, sleep disturbances were associated with attenuated psychotic symptoms and functional outcomes cross-sectionally and longitudinally. Only one study investigated the relationship between sleep and QoL. The exploratory meta-analysis revealed a significant difference in self-reported sleep disturbances measured by the PSQI (mean difference in score: 3.30 (95% CI 1.87, 4.74), p < 0.00001) and SIPS (mean difference in score: 1.58 (95% CI 0.80, 2.35), p < 0.00001) of ARMS patients compared to control groups.

CONCLUSIONS

ARMS individuals report impaired sleep quality and reduced sleep quantity compared to healthy controls. However, further research is needed to explore the longitudinal relationship between sleep disruptions and QoL in early psychosis. Significant variations in how sleep is measured across studies highlight a need to assess disturbances to sleep using robust and consistent approaches in this patient group.

Major depression, sleep, hostility and body mass index are associated with impaired quality of life in schizophrenia. Results from the FACE-SZ cohort

BACKGROUND

Impaired Quality of life (QoL) in schizophrenia has been mostly associated with psychotic and mood symptomatology, insight and functioning so far.

AIMS

QoL levels remain unsatisfactory due to other factors we aim to explore.

METHOD

We have explored sleep quality with the Pittsburgh Sleep Quality Index, hostility with the Buss&Perry questionnaire, major depression with the Positive and Negative Syndrome Scale depressive factor, functioning with the Global Assessment of Functioning scale and weight gain with body mass index in addition to other classical QoL-associated factors.

RESULTS

559 patients (mean age=31 (SD 9) years, 74% male sex) were included in the national FACE-SZ cohort. Impaired QoL has been significantly associated with respectively major depression, impaired sleep quality, increased hostility, impaired functioning and impaired insight independently of age, sex, treatments, tobacco smoking and body mass index. Major depression was associated with impaired psychological and physical well-being, and impaired self-esteem. Impaired sleep quality has been associated with impaired psychological and physical well-being and sentimental life. Hostility has been associated with impaired psychological well-being and self-esteem, impaired friends' relationships and impaired autonomy. Weight was associated with impaired physical well-being. Tobacco smoking was associated with higher level of friends' relationships.

CONCLUSIONS

Major depression, sleep, hostility, and weight gain have been identified as potential targets to improve QoL in schizophrenia and should be implemented in the recommendations for good practice to optimize schizophrenia care.

Sleep-related memory consolidation in the psychosis spectrum phenotype

Sleep and memory processing impairments range from mild to severe in the psychosis spectrum. Relationships between memory processing and sleep characteristics have been described for schizophrenia, including unaffected first-degree relatives, but they are less clear across other high-risk groups within the psychosis spectrum. In this study, we investigated high-risk individuals with accumulated risk-factors for psychosis and subthreshold symptoms. Out of 1898 screened individuals, 44 age- and sex-matched participants were sub-grouped into those with substantial environmental risk factors for psychosis and subthreshold psychotic symptoms (high-risk group) and those without these phenotypes (low-risk controls). Four groups (high/low risk, morning/evening training) were trained and tested in the laboratory for sustained attention, motor skill memory (finger-tapping task) and declarative memory (word-pair learning task) immediately after training, again after a night of EEG-recorded sleep at home or a period of daytime wakefulness, and again after 24 h from training. No differences in sustained attention or in memory consolidation of declarative and motor skill memory were found between groups for any time period tested. However, a group difference was found for rapid-eye movement (REM) sleep in relation to motor skill memory: the longer the total sleep time, particularly longer REM sleep, the greater the performance gain, which occurred only in high-risk individuals. In conclusion, our results suggest a gain in motor skill performance with sufficient sleep opportunity for longer REM sleep in high-risk individuals with subthreshold psychotic symptoms. Declarative memory did not benefit from sleep consolidation above or beyond that of the control group.

Disrupted Sleep and Circadian Rhythms in Schizophrenia and Their Interaction With Dopamine Signaling

Sleep and circadian rhythm disruption (SCRD) is a common feature of schizophrenia, and is associated with symptom severity and patient quality of life. It is commonly manifested as disturbances to the sleep/wake cycle, with sleep abnormalities occurring in up to 80% of patients, making it one of the most common symptoms of this disorder. Severe circadian misalignment has also been reported, including non-24 h periods and phase advances and delays. In parallel, there are alterations to physiological circadian parameters such as body temperature and rhythmic hormone production. At the molecular level, alterations in the rhythmic expression of core clock genes indicate a dysfunctional circadian clock. Furthermore, genetic association studies have demonstrated that mutations in several clock genes are associated with a higher risk of schizophrenia. Collectively, the evidence strongly suggests that sleep and circadian disruption is not only a symptom of schizophrenia but also plays an important causal role in this disorder. The alterations in dopamine signaling that occur in schizophrenia are likely to be central to this role. Dopamine is well-documented to be involved in the regulation of the sleep/wake cycle, in which it acts to promote wakefulness, such that elevated dopamine levels can disturb sleep. There is also evidence for the influence of dopamine on the circadian clock, such as through entrainment of the master clock in the suprachiasmatic nuclei (SCN), and dopamine signaling itself is under circadian control. Therefore dopamine is closely linked with sleep and the circadian system; it appears that they have a complex, bidirectional relationship in the pathogenesis of schizophrenia, such that disturbances to one exacerbate abnormalities in the other. This review will provide an overview of the evidence for a role of SCRD in schizophrenia, and examine the interplay of this with altered dopamine signaling. We will assess the evidence to suggest common underlying mechanisms in the regulation of sleep/circadian rhythms and the pathophysiology of schizophrenia. Improvements in sleep are associated with improvements in symptoms, along with quality of life measures such as cognitive ability and employability. Therefore the circadian system holds valuable potential as a new therapeutic target for this disorder.

Insomnia and suicidal ideation in nonaffective psychosis

Study Objectives

Insomnia is a common symptom in the clinical course of schizophrenia. There is a robust association between insomnia and suicidality in other psychiatric disorders. Two previous studies found associations between insomnia and suicide attempt or completed suicide in patients with schizophrenia. We hypothesized that greater insomnia would be associated with greater levels of suicidal ideation in patients with schizophrenia and other nonaffective psychoses.

Methods

We recruited 108 inpatients and outpatients age 18-65 between July 2010 and July 2016 with DSM-IV nonaffective psychosis (schizophrenia, schizoaffective disorder, or schizophreniform disorder). We investigated relationships between current insomnia (Insomnia Severity Index [ISI]), suicidal ideation over the past week, and lifetime history of suicide attempt (Beck Scale for Suicide Ideation [BSS]) in regression analyses.

Results

After controlling for potential confounders, insomnia was a significant indicator of suicidal ideation (β = 0.27, p = 0.032). Insomnia was also a significant indicator of a high BSS score (≥16; OR = 1.14, 95% CI: 1.01-1.28, p = 0.029). Furthermore, participants with severe insomnia were almost 15 times more likely to have a lifetime history suicide attempt than participants without current insomnia (OR = 14.8, 95% CI: 1.4-157, p = 0.025). Insomnia was also an indicator of greater PANSS total (β = 0.33, p = 0.001), positive subscale (β = 0.32, p = 0.002), and general subscale (β = 0.40, p < 0.001) scores.

Conclusions

Insomnia is associated with suicidal ideation, lifetime suicide attempt, and greater psychopathology in patients with schizophrenia. Our findings suggest that formal assessment of insomnia may be germane to the clinical care of patients with schizophrenia as a marker of suicide risk and symptom severity.

Prevalence, dimensionality and clinical relevance of self-disturbances and psychotic-like experiences in Polish young adults: a latent class analysis approach

OBJECTIVES

We aimed to investigate latent classes of psychotic-like experiences (PLEs) and self-disturbances (SD) and to explore mutual overlapping between derived subgroups. Further, our goal was to investigate class membership relationship with an exposure to childhood trauma and different psychopathological factors such as cognitive biases, depression, insomnia, psychiatric diagnosis and lifetime suicidality.

METHODS

Participants consist of 3167 non-clinical adults. We performed two latent class analyses (LCA), for PLEs and SD separately, to identify subgroups of individuals with different profiles on PLEs and SD. Associations between psychopathological factors and latent class membership were examined using multinomial logistic regression analysis.

RESULTS

LCA produced 5 classes within SD and 3 classes within PLEs. Class of the highest endorsement of SD showed 53% overlap with class of the highest endorsement of PLEs. The highest risk of belonging to High Class for both SD and PLEs was associated in particular with depression, cognitive biases and insomnia. Trauma emerged as a significant predictor only for PLEs classes.

CONCLUSIONS

Our findings confirm that high PLEs and SD co-occur and are concentrated in a relatively small number of individuals, at least in the general population. Their combination may capture the highest risk of psychosis in the general population.

Decreased need for sleep as an endophenotype of bipolar disorder: an actigraphy study

Reports of subjective sleep impairments have been replicated in adults with bipolar disorder (BD), young BD patients, and even children of parents with BD. Furthermore, circadian rhythm alterations are a core feature of BD. Despite the impairment in circadian rhythms and altered sleep included in various heuristic developmental models of BD, thus far, biomarkers have not been sufficiently objectively validated. Thus, here, we assessed the rest-activity circadian rhythmicity and sleep macrostructure using actigraphy in a sample of unaffected child and adolescent offspring of bipolar parents (BO; n = 43; 21 females; 11.0 ± 3.2 years) and controls (n = 42; 17 females; 11.1 ± 3.4 years) comparable in sex (p = .4) and age (p = .7). All participants wore a MotionWatch 8 (Camntech, Cambridge, UK) actigraph on their nondominant wrist for ≥ 14 days and completed sleep diaries. Psychopathology was assessed by the Kiddie Schedule for Affective Disorders and Schizophrenia and by subjective scales. The main areas of interest were rest-activity circadian rhythmicity, chronotype and sleep macrostructure. Subgroup analyses (child and adolescent subgroups) were conducted to identify physiological differences in sleep between these age groups. The BO and controls did not differ in the presence of current mood (p = .5) and anxiety (p = .6) disorders. The BO had shorter sleep time on free days (p = .007; effect size, Cohen´s d = 0.56), lower sleep efficiency on free days (p = .01; d = 0.47), lower prolongation of time in bed on free days (p = .046; d = 0.41), and lower social jet lag (p = .04; d = 0.5) than the controls. A longer sleep time on school days (p < .001; d = 0.21), lower prolongation of sleep time between school and free days (p = .008; d = 0.74), and larger difference in sleep onset latency between school days and free days (p = .009; d = 0.52) were observed in the adolescent BO than in the controls. The child BO had poorer sleep quality on free days than the controls (p = .02; d = 0.96). In all cases, the results remained significant after controlling for subthreshold mood and anxiety symptoms. The BO had less variable rest-activity rhythm than controls (p = .04; d = 0.32). No other significant differences between the BO and controls were observed in the rest-activity circadian rhythmicity and chronotype. The results showed decreased physiological catch-up sleep on free days in the BO, which may indicate a decreased need for sleep in this population. Thus, the decreased need for sleep observed in the unaffected BO may represent an endophenotype of BD.

Exome-Wide Meta-Analysis Identifies Rare 3'-UTR Variant in ERCC1/CD3EAP Associated with Symptoms of Sleep Apnea

Obstructive sleep apnea (OSA) is a common sleep breathing disorder associated with an increased risk of cardiovascular and cerebrovascular diseases and mortality. Although OSA is fairly heritable (~40%), there have been only few studies looking into the genetics of OSA. In the present study, we aimed to identify genetic variants associated with symptoms of sleep apnea by performing a whole-exome sequence meta-analysis of symptoms of sleep apnea in 1,475 individuals of European descent. We identified 17 rare genetic variants with at least suggestive evidence of significance. Replication in an independent dataset confirmed the association of a rare genetic variant (rs2229918; minor allele frequency = 0.3%) with symptoms of sleep apnea (p-value_meta = 6.98 × 10⁻⁹, β_meta = 0.99). Rs2229918 overlaps with the 3′ untranslated regions of ERCC1 and CD3EAP genes on chromosome 19q13. Both genes are expressed in tissues in the neck area, such as the tongue, muscles, cartilage and the trachea. Further, CD3EAP is localized in the nucleus and mitochondria and involved in the tumor necrosis factor-alpha/nuclear factor kappa B signaling pathway. Our results and biological functions of CD3EAP/ERCC1 genes suggest that the 19q13 locus is interesting for further OSA research.