Correlates of sleep irregularity in schizophrenia

Sleep and socio-occupational functioning in adults with serious mental illness: A systematic review

Sleep is a crucial factor influencing mental health and quality of life. Individuals with serious mental illness (SMI) often experience significant sleep problems. This can further exacerbate their symptoms and impact their socio-occupational functioning (SOF) (the extent to which a person is able to engage in 'self-care and activities of daily living, communication, interpersonal relations, instrumental living skills, and work'). Despite the well-established bidirectional relationship between sleep and mental health, the specific association between sleep and SOF in the context of SMI remains underexplored. A systematic review was conducted. Comprehensive searches in PubMed and PsycNet yielded 832 results. After applying inclusion criteria, 24 studies were included in the narrative synthesis. Study characteristics and key findings were extracted for analysis. Collectively, studies investigated sleep quality, satisfaction, duration, disturbance, specific disorders, and objectively-recorded sleep parameters across various study designs. Studies included a total population of 10,938, utilising a range of sleep and SOF outcome measures. Nearly all studies indicated that worsened sleep was associated with reduced SOF in SMI populations. The review supports the potential role of improved sleep as a route to improved SOF in SMI populations. This has clear implications for research and clinical care for patients with SMI.

Social support and sleep quality in people with schizophrenia living in the community: the mediating roles of anxiety and depression symptoms

Introduction

Research has demonstrated that higher social support is associated with better psychological health, quality of life, cognition, activities of daily living, and social participation, but the relationship between social support and sleep quality remains unknown. This study aims to investigate the mediating effects of anxiety and depression in the relationship between social support and sleep among community-dwelling patients with schizophrenia.

Method

Purposive sampling was used to collect face-to-face data from 1,107 community-dwelling patients with schizophrenia in Chengdu, Sichuan Province, China, between April and July 2023. The Athens Insomnia Scale (AIS) was used to assess sleep quality; the Generalized Anxiety Disorder 7-item scale (GAD-7) was utilized to evaluate anxiety symptoms; and the Patient Health Questionnaire-9 (PHQ-9) was employed to assess depressive symptoms. The mediating effect of anxiety and depression symptoms was assessed using the bootstrap method via Model 6 (Serial multiple mediator model) of the SPSS PROCESS macro.

Results

Among the 1,107 participants, the proportions of people with schizophrenia experiencing anxiety, depressive symptoms, and poor sleep quality were 22.8, 37.7, and 42.1%, respectively. Mediation analyses indicated that although social support had no direct effect on sleep quality, anxiety and depressive symptoms fully mediated the relationship between social support and sleep quality.

Conclusion

Patients with schizophrenia experience low levels of social support and poor sleep quality. To enhance the sleep quality of individuals with schizophrenia, all levels of society (government, medical institutions, and communities) must pay more attention to mental health. Implementing diverse intervention measures to strengthen social support and improve symptoms of anxiety and depression should be considered. This approach may potentially lead to an improvement in sleep quality among individuals with schizophrenia.

Influence of White Sound on Sleep Quality, Anxiety, and Depression in Patients with Schizophrenia

BACKGROUND

Patients with schizophrenia frequently experience issues such as poor sleep quality, anxiety, and depression. White sound has been identified as a potential therapeutic strategy to enhance sleep quality and alleviate negative emotions. This study aimed to investigate the effectiveness of white sound in improving sleep quality, anxiety, and depression among patients with schizophrenia.

MATERIALS AND METHODS

This retrospective analysis included clinical data from 212 patients with schizophrenia divided into two groups based on their treatment approach. Group C (control, without white sound, n = 106) received standard pharmacological treatments, while group W (white sound, n = 106) was exposed to white sound (40-50 dB) for 2 hours nightly at 9:00 pm. All patients were assessed using the Pittsburgh Sleep Quality Index (PSQI), Hamilton Depression Scale (HAMD), Hamilton Anxiety Scale (HAMA), and Positive and Negative Syndrome Scale (PANSS) before and after 12 weeks of intervention.

RESULTS

After 12 weeks, group W showed significant improvements in sleep latency, sleep efficiency, and overall PSQI scores compared to group C (P < 0.05). Furthermore, the HAMD and HAMA scores were significantly lower in group W (P < 0.05), indicating reduced levels of anxiety and depression. The negative symptoms score was significantly lower in group W (P < 0.05) after treatment.

CONCLUSION

White sound shows promise in improving sleep quality, and alleviating anxiety and depression in patients with schizophrenia.

Circadian rhythmicity in schizophrenia male patients with and without substance use disorder comorbidity

Circadian rhythmicity is associated to clinical variables that play an important role in both schizophrenia (SZ) and substance use disorders (SUD), although the characteristics of the coexistence of these two diagnoses (SZ +) remain mostly unknown. Hence, we studied a sample of 165 male patients divided in three groups each of 55, according to their diagnoses (SZ + , SZ, and SUD), as well as a healthy control (HC; n = 90) group. Alongside with sociodemographic and clinical variables, circadian rhythms were registered through a sleep-wake data structured interview, a circadian typology questionnaire, and distal skin temperature (DST) using the Thermochron iButton every 2 min during 48 h. Analyses showed that SZ + and SZ patients presented a longer sleep (delay in wake-up time) and mostly an intermediate circadian typology, while SUD patients slept less hours, displaying a morning typology. The DST showed the highest daily activation and stability for the SUD group, even when compared with the HC group. The presence of schizophrenia (SZ + and SZ) was related to a DST pattern with a reduced amplitude determined by a wakefulness impairment, which was more pronounced for SZ patients whose sleep period was adequate. The assessment of circadian rhythms in under treatment male patients with SZ should be focused on the diurnal period as a possible marker of either treatment adherence or patient's recovery, irrespective of the presence of a comorbid SUD. Further research with additional objective measures may provide knowledge transferable to therapeutic strategies and could be useful to establish possible endophenotypes in the future.

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.

Remote sensing mental health: A systematic review of factors essential to clinical translation from validation research

Background

Mental illness remains a major global health challenge largely due to the absence of definitive biomarkers applicable to diagnostics and care processes. Although remote sensing technologies, embedded in devices such as smartphones and wearables, offer a promising avenue for improved mental health assessments, their clinical integration has been slow.

Objective

This scoping review, following preferred reporting items for systematic reviews and meta-analyses guidelines, explores validation studies of remote sensing in clinical mental health populations, aiming to identify critical factors for clinical translation.

Methods

Comprehensive searches were conducted in six databases. The analysis, using narrative synthesis, examined clinical and socio-demographic characteristics of the populations studied, sensing purposes, temporal considerations and reference mental health assessments used for validation.

Results

The narrative synthesis of 50 included studies indicates that ten different sensor types have been studied for tracking and diagnosing mental illnesses, primarily focusing on physical activity and sleep patterns. There were many variations in the sensor methodologies used that may affect data quality and participant burden. Observation durations, and thus data resolution, varied by patient diagnosis. Currently, reference assessments predominantly rely on deficit focussed self-reports, and socio-demographic information is underreported, therefore representativeness of the general population is uncertain.

Conclusion

To fully harness the potential of remote sensing in mental health, issues such as reliance on self-reported assessments, and lack of socio-demographic context pertaining to generalizability need to be addressed. Striking a balance between resolution, data quality, and participant burden whilst clearly reporting limitations, will ensure effective technology use. The scant reporting on participants' socio-demographic data suggests a knowledge gap in understanding the effectiveness of passive sensing techniques in disadvantaged populations.

Alexithymia is associated with insomnia in Chinese patients with schizophrenia

Background

Sleep disorders are prevalent among patients with schizophrenia and are associated with several negative consequences. Although, researchers have recently suggested that sleep disorders have a close correlation with alexithymia, and schizophrenia also has a strong correlation with alexithymia, there have been few studies on the relationships between schizophrenia, sleep disorders and alexithymia. Therefore, this study aimed to explore the relationships between psychiatric symptoms, alexithymia and sleep problems in patients with schizophrenia so as to provide a reference for the clinical treatment of this comorbidity.

Methods

In total, 977 patients with schizophrenia were recruited for this study. The Insomnia Severity Index (ISI) was used to assess sleep disorders, and the Positive and Negative Syndrome Scale (PANSS), Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and Toronto Alexithymia Scale (TAS) were used to evaluate clinical symptoms, cognitive functions and the ability to express emotion, respectively.

Results

The results indicated that the PANSS subscales (G-subscore) and TAS group were risk factors for insomnia in schizophrenia patients (all p < 0.05). The mediation model showed the standardized path coefficients from schizophrenia to alexithymia (β = 0.104, p < 0.001) and from alexithymia to insomnia (β = 0.038, p < 0.001) were statistically significant.

Conclusion

The results of this study indicated that alexithymia is associated with sleep disturbance in patients with schizophrenia. These findings may provide a new avenue for the treatment of schizophrenia patients with sleep disorders.

The relationship between sleep and suicidality in schizophrenia spectrum and other psychotic disorders: A systematic review

Individuals with Schizophrenia Spectrum Disorders (SSDs) have significantly higher rates of suicidal thoughts, attempts, and death by suicide in comparison to the general population. Sleep disturbances (reduced duration, timing and quality of sleep) are risk factors for suicidality in the general population, with research indicating the relationship is both immediate and accumulative. Sleep disturbances are also considered to be implicated in the onset and exacerbation of psychotic symptoms in SSDs. Reducing the risk of suicidality in SSDs remains an important public health priority, thus exploration of contributing risk factors is warranted. Sleep monitoring may also offer an adjunct risk monitoring method to suicidality assessments in SSDs, and a potential treatment target for psychotic symptoms. This review aimed to explore proximal and longitudinal relationships between self-reported and objectively measured sleep and suicidality in SSDs and other psychotic disorders. A comprehensive search of four databases was conducted. Eleven studies met the inclusion criteria (10 cross sectional and 1 longitudinal). Narrative synthesis indicated that self-reported sleep disturbances and sleep disorders (e.g. insomnia) were associated with increased risk of suicidal ideation and attempt. However, one study employing polysomnography did not find sleep to be associated with suicidality. Methodological limitations of the evidence base include: i) little experimental or longitudinal evidence, (ii) self-report and/or single item assessment of sleep disturbance, (iii) limited use of validated measures of suicidality, (iv) considerable research in long-term schizophrenia but sparse evidence in early psychosis. Future research should explore (i) cross-sectional and longitudinal relationships between specific aspects of suicidality and objective sleep parameters, (ii) use qualitative or mixed-methods designs to disentangle the nuances and bidirectionality in the sleep-suicide relationship, (iii) explore the psychological processes underpinning or mediating the sleep-suicide relationship in SSDs.

The relationship between subjective sleep disturbance and attenuated psychotic symptoms after accounting for anxiety and depressive symptoms

BACKGROUND AND HYPOTHESES

Sleep disturbances are increasingly recognized as cooccurring with psychotic symptoms. The potential importance of this relationship is complicated when considering the effects of anxiety and depressive symptoms which commonly present in early-stage illness states. This study aimed to investigate the relationship between self-reported sleep disturbance on the development of attenuated psychotic symptoms (APS) cross-sectionally and longitudinally while adjusting for roles of anxiety and depressive symptoms.

DESIGN

Eight-hundred and two help-seeking young people aged 12 to 25 years who engaged with our Australian early intervention services were included in the study (the "Transitions" cohort). Cross sectional mediation and cross-lagged longitudinal (12-month) mediation models were developed with outcomes being different APS domains.

RESULTS

Only baseline excessive daytime sleepiness predicted later APS when accounting for previous APS, anxiety and depressive symptomatology. Cross sectionally, self-reported sleep disturbance showed both direct and indirect predictive relationships with all APS domains. Partial mediation through anxiety and depression was shown for unusual thought content, perceptual abnormalities, and disorganised speech, while full mediation through depression was shown for non-bizarre ideas.

CONCLUSIONS

The specificity of the relationship between self-reported sleep disturbance on APS highlights the potential for different roles in mechanistic models of psychotic symptom expression. This further indicates the need for further experimental research to illuminate potential causal pathways. Future research should continue to use continuous, symptom level approaches across a range of timeframes to more accurately model the complex dynamics present in the sleep-psychosis relationship.

Circadian functioning and quality of life in substance use disorder patients with and without comorbid schizophrenia

Sleep disturbances are strongly linked with mental diseases such as substance use disorder (SUD) or schizophrenia (SZ) which can have a detrimental impact on quality of life (QOL), especially when both disorders are comorbid (dual disorder). In absence of studies about both circadian characteristics and QOL in patients with SUD and comorbid SZ (SUD + SZ), we examined a sample of 155 male under treatment, 75 with SUD + SZ and 80 only with SUD. Circadian functioning was evaluated by chronotype, social jet-lag and sleep quality (using the Pittsburgh Sleep Quality Index, PSQI), while the QOL was obtained by the World Health Organization's Quality of Life Questionnaire (WHOQOL)-BREF. SUD + SZ patients were more evening type than SUD, and this chronotype was linked to polydrug use in total sample and SUD + SZ group. We observed that the comorbidity did not lead to worse sleep quality in the SUD and SUD + SZ patients. QOL was poorer in SUD + SZ patients, who showed a negative association of Physical health, Psychological health and Social relationship with suicide attempts and severity of SZ. Lastly, patients with worse QOL also reported poorer sleep quality suggesting that treatment could include circadian adjustments along with a focused approach to lifestyle improvement.

Physical Activity and Sleep in 11-Year Old Children With a Familial High Risk of Schizophrenia or Bipolar Disorder. The Danish High Risk and Resilience Study-VIA 11

Objective

People with schizophrenia and bipolar disorder are at increased risk of having comorbid somatic illness. This is partly due to lack of physical activity, which may originate from childhood. Sleep disturbances are associated with schizophrenia and bipolar disorder. We aimed to assess physical activity and sleep in children at familial high risk of schizophrenia or bipolar disorder and population-based controls.

Methods

This study is part of The Danish High Risk and Resilience Study-VIA 11. Children aged 11 born to parents with schizophrenia (FHR-SZ) (N = 133), bipolar disorder (FHR-BP) (N = 84), or controls (C) (N = 150) were assessed by accelerometry for an average of 6.9 days.

Results

High-intensity physical activity was significantly lower in children at FHR-SZ and FHR-BP compared to controls, (mean hours per day for FHR-SZ: 0.29, SD 0.19, for FHR-BP: 0.27, SD 0.24, and for controls 0.38, SD 0.22, P = <.001). Sleep did not differ between the groups.

Conclusion

Children at FHR-SZ or FHR-BP had less physical activity compared to controls. Our study highlights a research area that reveals a hitherto unexplored disadvantage of being born to parents with schizophrenia or bipolar disorder. Further research is needed to enhance better understanding of causal pathways and consequences of reduced physical activity in children with FHR-SZ and FHR-BP.

Sleep Abnormalities in Schizophrenia: State of the Art and Next Steps

Sleep disturbances are commonly observed in schizophrenia, including in chronic, early-course, and first-episode patients. This has generated considerable interest, both in clinical and research endeavors, in characterizing the relationship between disturbed sleep and schizophrenia. Sleep features can be objectively assessed with EEG recordings. Traditionally, EEG studies have focused on sleep architecture, which includes non-REM and REM sleep stages. More recently, numerous studies have investigated alterations in sleep-specific rhythms, including EEG oscillations, such as sleep spindles and slow waves, in individuals with schizophrenia compared with control subjects. In this article, the author reviews state-of-the-art evidence of disturbed sleep in schizophrenia, starting from the relationship between sleep disturbances and clinical symptoms. First, the author presents studies demonstrating abnormalities in sleep architecture and sleep-oscillatory rhythms in schizophrenia and related psychotic disorders, with an emphasis on recent work demonstrating sleep spindles and slow-wave deficits in early-course and first-episode schizophrenia. Next, the author shows how these sleep abnormalities relate to the cognitive impairments in patients diagnosed with schizophrenia and point to dysfunctions in underlying thalamocortical circuits, Ca+ channel activity, and GABA-glutamate neurotransmission. Finally, the author discusses some of the next steps needed to further establish the role of altered sleep in schizophrenia, including the need to investigate sleep abnormalities across the psychotic spectrum and to establish their relationship with circadian disturbances, which in turn will contribute to the development of novel sleep-informed treatment interventions.

Circadian Characteristics in Patients under Treatment for Substance Use Disorders and Severe Mental Illness (Schizophrenia, Major Depression and Bipolar Disorder)

Dual disorders (substance use and mental illness comorbidity) are a condition that has been strongly associated with severe symptomatology and clinical complications. The study of circadian characteristics in patients with Severe Mental Illness or Substance Use Disorder (SUD) has shown that such variables are related with mood symptoms and worse recovery. In absence of studies about circadian characteristics in patients with dual disorders we examined a sample of 114 male participants with SUD and comorbid Schizophrenia (SZ+; n = 38), Bipolar Disorder (BD+; n = 36) and Major Depressive Disorder (MDD+; n = 40). The possible differences in the sample of patients according to their psychiatric diagnosis, circadian functioning with recordings of distal skin temperature during 48 h (Thermochron iButton^®), circadian typology and sleep-wake schedules were explored. MDD+ patients were more morning-type, while SZ+ and BD+ had an intermediate-type; the morning-type was more frequent among participants under inpatient SUD treatment. SZ+ patients had the highest amount of sleeping hours, lowest arousal and highest drowsiness followed by BD+ and MDD+, respectively. These observed differences suggest that treatment for patients with dual disorders could include chronobiological strategies to help them synchronize patterns with the day-light cycle, since morning-type is associated with better outcomes and recovery.

The association between chronotype and sleep quality, and cardiometabolic markers in patients with schizophrenia

Current data on chronotype and sleep quality and their relationship with clinical characteristics of schizophrenia are insufficient to evaluate whether these variables are associated with cardiometabolic risk. We aimed to identify the interplay between chronotype, sleep quality and metabolic indices that can potentially predict negative cardiometabolic outcomes in schizophrenia patients. One-hundred schizophrenia patients who were under a stable antipsychotic regime were enrolled in the study. Clinical information, anthropometric measurements, as well as recent metabolic parameters including serum lipids, atherogenic, and metabolic indices suggestive of cardiometabolic risk were recorded. High and low sleep quality groups (HSQ and LSQ) were determined via the Pittsburgh Sleep Quality Index and chronotypes were evaluated with the Morningness-Eveningness Questionaire. Patients with eveningness chronotype had poorer sleep quality compared to intermediate or morningness (p = .017) patients. The LSQ group had higher total cholesterol (p = .004) and low-density lipoprotein (LDL) (p = .041) compared to the HSQ group. Mean blood pressure was higher in the eveningness chronotype patients compared to intermediate or morningness patients (p = .015). According to a logistic regression model, total cholesterol, disposition index, and having an eveningness chronotype significantly predicted LSQ in schizophrenia. Eveningness chronotype may lead to impaired cardiometabolic regulation with the mediation of poor sleep quality in schizophrenia patients. Cardiovascular diseases, sleep quality, and sleep patterns can influence each other; thus, this complex relationship in schizophrenia should be considered while configuring both pharmacological and behavioral interventions.

Chronotype in individuals with schizophrenia: A meta-analysis

OBJECTIVE

Emerging evidence shows that evening chronotype is associated with mental health problems, especially mood disorders, but few studies have investigated its association with schizophrenia. Based on meta-analytic methods, we aimed to test whether eveningness is greater in individuals with schizophrenia compared with healthy controls and patients with bipolar I disorder.

METHOD

Medline/Pubmed, Google Scholar, and EBSCO databases were searched up to April 2021 for articles investigating chronotype in individuals with schizophrenia. Two meta-analyses were conducted: individuals with schizophrenia compared with healthy controls and individuals with bipolar I disorder. These meta-analyses were followed by a meta-regression controlling for potential confounders.

RESULTS

Five studies comprising 386 individuals with schizophrenia (age 32.73 years; 67.4% male), 320 with bipolar I disorder (age 31.26 years; 38.3% male) and 638 healthy controls (age 32.19 years; 50.6% male) were included. Participants with schizophrenia were moderately higher on eveningness than healthy controls but they did not differ from those with bipolar I disorder. The difference was not affected by gender, age, and the type of scale used for assessing chronotype.

CONCLUSIONS

Individuals with schizophrenia are more evening oriented than healthy controls and have a similar chronotype to those with bipolar I disorder. The results supported the hypothesis that evening chronotype might be a marker of, or a risk factor for, mental health problems in general and not just limited to affective disorders.

"Assessing the Psychometric Properties of the PROMIS Sleep Measures in Persons with Psychosis."

An accumulation of research has indicated that persons with psychotic disorders experience a variety of sleep disturbances. However, few studies have examined the psychometric properties of sleep assessments that are utilized in this population. We conducted two studies to examine the reliability and validity of the PROMISTM Sleep Disturbance and Sleep-Related Impairment scales in outpatient samples of persons with psychosis. In Study 1, we examined the internal consistency and convergent validity of the PROMIS sleep scales in individuals with various psychotic disorders (N = 98) and healthy controls (N = 22). The PROMIS sleep scales showed acceptable internal consistency and convergent validity in both healthy controls and individuals with psychotic disorders. In addition, replicating prior research, the PROMIS scales identified greater sleep disturbance and sleep-related impairment in participants with psychotic disorders compared to healthy controls. In Study 2, we examined the test-retest reliability (M = 358 days) of the PROMIS sleep scales in a subset (N = 37) of persons with psychotic disorders who previously participated in Study 1. We also assessed the relation between these self-report measures and actigraph sleep parameters. The results showed that PROMIS sleep measures demonstrated modest temporal stability in the current sample. Contrary to our hypothesis, there was a lack of correspondence between these scales and actigraph sleep parameters. Overall, these findings indicate that the PROMIS sleep scales are psychometrically sound measures for populations with psychosis and highlight the importance of utilizing a multi-method approach to assess sleep.

Sleep disturbances and cognitive impairment in schizophrenia spectrum disorders: a systematic review and narrative synthesis

Individuals with schizophrenia spectrum disorders (SSD) experience frequent sleep disturbances in addition to enduring cognitive impairments. The purpose of the present review was to systematically summarise our current understanding of the association between sleep disturbances and cognition in SSD. Through this, it was aimed to identify features of disturbed sleep that are reliably associated with cognitive deficits in SSD and identify the gaps within the current literature that require future investigation. Eighteen relevant studies were identified following a two-stage screening process. Following a structured narrative synthesis of key study components, no clear and consistent pattern emerged. Considerable methodological variability was present amongst the reviewed studies. Although some broad consistencies were identified, such as associations between sleep spindle density and sleep-dependent memory consolidation, the overall pattern of results lacked a cohesive composition due to the diverse list of sleep parameters and cognitive domains investigated, as well as a lack of replication. Additional research is needed before more definitive remarks can be made regarding the influence of sleep disturbances on cognitive function in SSD.

Candidate symptomatic markers for predicting violence in schizophrenia: A cross-sectional study of 7711 patients in a Chinese population

OBJECTIVE

Violent behaviour is an alarming problem among schizophrenia patients. The effects of historical, clinical, and pathological risk factors for violence have been investigated by multiple studies, but consensus has not been achieved. As psychotic symptoms are more direct and intuitive indicators for violence, identifying robustly associated symptoms is a crucial part of the future prediction and precise management of violent patients in clinics. This study aims to identify the psychotic symptoms correlated with violence among schizophrenia patients in a Chinese population.

METHODS

In this cross-sectional study, the medical records of 7711 schizophrenia patients (4711 in the discovery set and 3000 in the validation set) were collected from 1998 to 2010. Their psychotic symptoms were extracted, and the patients were divided into violent and non-violent groups. Multivariate logistic analysis was applied to identify symptoms associated with violence in the discovery set.

RESULTS

Eight psychotic symptoms were found to be significantly correlated with violence in schizophrenia. "Destruction of property", "verbal aggression" and "insomnia" increased the risk of violence, while "flat affect", "delusion of persecution", "auditory hallucination", "vagueness of thought" and "poverty of thought" decreased the risk of violence. The regression model was evaluated by receiver operating characteristic (ROC) analysis for its discriminatory performance, achieving area under curve (AUC) values of 0.887 in the discovery sample set and 0.824 in the validation sample set.

CONCLUSIONS

The correlated symptoms identified by this study can serve as future candidate predictors for violence in schizophrenia, paving the way for precise management of schizophrenia patients in clinics.

Measuring sleep regularity: Theoretical properties and practical usage of existing metrics

STUDY OBJECTIVES

Sleep regularity predicts many health-related outcomes. Currently, however, there is no systematic approach to measuring sleep regularity. Traditionally, metrics have assessed deviations in sleep patterns from an individual's average. Traditional metrics include intra-individual standard deviation (StDev), Interdaily Stability (IS), and Social Jet Lag (SJL). Two metrics were recently proposed that instead measure variability between consecutive days: Composite Phase Deviation (CPD) and Sleep Regularity Index (SRI). Using large-scale simulations, we investigated the theoretical properties of these five metrics.

METHODS

Multiple sleep-wake patterns were systematically simulated, including variability in daily sleep timing and/or duration. Average estimates and 95% confidence intervals were calculated for six scenarios that affect measurement of sleep regularity: 'scrambling' the order of days; daily vs. weekly variation; naps; awakenings; 'all-nighters'; and length of study.

RESULTS

SJL measured weekly but not daily changes. Scrambling did not affect StDev or IS, but did affect CPD and SRI; these metrics, therefore, measure sleep regularity on multi-day and day-to-day timescales, respectively. StDev and CPD did not capture sleep fragmentation. IS and SRI behaved similarly in response to naps and awakenings but differed markedly for all-nighters. StDev and IS required over a week of sleep-wake data for unbiased estimates, whereas CPD and SRI required larger sample sizes to detect group differences.

CONCLUSIONS

Deciding which sleep regularity metric is most appropriate for a given study depends on a combination of the type of data gathered, the study length and sample size, and which aspects of sleep regularity are most pertinent to the research question.

Sleep Disturbances in Patients with Persistent Delusions: Prevalence, Clinical Associations, and Therapeutic Strategies

Sleep disturbances accompany almost all mental illnesses, either because sound sleep and mental well-being share similar requisites, or because mental problems lead to sleep problems, or vice versa. The aim of this narrative review was to examine sleep in patients with delusions, particularly in those diagnosed with delusional disorder. We did this in sequence, first for psychiatric illness in general, then for psychotic illnesses where delusions are prevalent symptoms, and then for delusional disorder. The review also looked at the effect on sleep parameters of individual symptoms commonly seen in delusional disorder (paranoia, cognitive distortions, suicidal thoughts) and searched the evidence base for indications of antipsychotic drug effects on sleep. It subsequently evaluated the influence of sleep therapies on psychotic symptoms, particularly delusions. The review’s findings are clinically important. Delusional symptoms and sleep quality influence one another reciprocally. Effective treatment of sleep problems is of potential benefit to patients with persistent delusions, but may be difficult to implement in the absence of an established therapeutic relationship and an appropriate pharmacologic regimen. As one symptom can aggravate another, comorbidities in patients with serious mental illness all need to be treated, a task that requires close liaison among medical specialties.

Subjective-Objective Sleep Discrepancy in Schizophrenia

OBJECTIVE/BACKGROUND

Subjective methods are often employed for sleep assessment due to their ease of use, but the results may not concur with objective findings. This discrepancy may be present in schizophrenia; however, limited data are available. We performed a secondary analysis to evaluate the agreement between 1-week actigraphy and sleep diary-derived parameters and factors that contribute to subjective-objective sleep discrepancy.

PARTICIPANTS

66 outpatients with schizophrenia (mean age = 44.08 years; 45.45% males).

METHODS

Agreement between subjective-objective parameters was assessed using two-way repeated measures ANOVA, Pearson's correlation, and Bland-Altman plot. The magnitude of discrepancy was quantified using Cohen's d. Pearson's correlation was used to determine the significant factors of subjective-objective sleep discrepancy. Benjamini-Hochberg adjustment was performed to account for multiple testing.

RESULTS

On average, sleep diaries overestimated sleep onset latency by 20.45 min, total sleep time by 37.63 min, and sleep efficiency by 4.29%, but underestimated wake after sleep onset by 33.28 min. Cohen's d ranged between 0.61 and 1.41. Subjective-objective discrepancies were significantly associated with marital and employment status, self-reported sleep disturbance, delayed sleep-wake phase disorder, chronotype, and psychosocial functioning (r = 0.32-0.44; Benjamini-Hochberg corrected p < .05).

CONCLUSIONS

Our findings show that differences between subjective and objective measurements of sleep are present in schizophrenia. Although actigraphy is not a standard procedure for sleep disturbance in schizophrenia, clinical judgment should be used if patients are suspected to have overestimated their sleep difficulties. Further studies should examine whether feedback based on actigraphy can benefit patients with schizophrenia and comorbid sleep disturbances.

Sleep and schizophrenia: From epiphenomenon to treatable causal target

BACKGROUND

Sleep disturbance is a common clinical issue for patients with psychosis. It has been identified as a putative causal factor in the onset and persistence of psychotic experiences (paranoia and hallucinations). Hence sleep disruption may be a potential treatment target to prevent the onset of psychosis and reduce persistent psychotic experiences. The aim of this review is to describe developments in understanding the nature, causal role, and treatment of sleep disruption in psychosis.

METHOD

A systematic literature search was conducted to identify studies, published in the last five years, investigating subjective sleep disruption and psychotic experiences.

RESULTS

Fifty-eight papers were identified: 37 clinical and 21 non-clinical studies. The studies were correlational (n = 38; 20 clinical, 18 non-clinical), treatment (n = 7; 1 non-clinical), qualitative accounts (n = 6 clinical), prevalence estimates (n = 5 clinical), and experimental tests (n = 2 non-clinical). Insomnia (50%) and nightmare disorder (48%) are the most prevalent sleep problems found in patients. Sleep disruption predicts the onset and persistence of psychotic experiences such as paranoia and hallucinations, with negative affect identified as a partial mediator of this relationship. Patients recognise the detrimental effects of disrupted sleep and are keen for treatment. All psychological intervention studies reported large effect size improvements in sleep and there may be modest resultant improvements in psychotic experiences.

CONCLUSIONS

Sleep disruption is a treatable clinical problem in patients with psychosis. It is important to treat in its own right but may also lessen psychotic experiences. Research is required on how this knowledge can be implemented in clinical services.

Sleep disturbance and sleep-related impairment in psychotic disorders are related to both positive and negative symptoms

A large literature indicates that sleep disturbances are associated with paranoia and other positive symptoms in psychotic disorders. However, few studies have examined the potential association between sleep disturbances and negative symptoms and the results have been inconsistent. The current study examined the hypothesis that sleep problems would be associated with more severe positive and negative symptoms in a transdiagnostic sample of individuals with psychosis (N = 90). Further, we examined whether sleep would be related to negative symptoms above and beyond the contribution of paranoia, other positive symptoms, and depression-anxiety. Results replicated prior research in finding that both sleep disturbance and sleep-related impairment were related to more severe paranoia, other positive symptoms and depression-anxiety. Consistent with our hypothesis, more severe sleep disturbance and sleep-related impairment were related to greater negative symptoms; this was evident across both motivation-pleasure deficits and diminished expression. Sleep variables remained significantly related to motivation-pleasure deficits even after controlling for other non-negative symptoms. These results indicate the broad symptom impact of sleep disturbances and may suggest a novel treatment target to improve negative symptoms.

Irregular Sleep-Wake Rhythm Disorder

This article focuses on irregular sleep-wake rhythm disorder (ISWRD) and its associations with several other comorbidities. Irregular sleep-wake rhythm disorder is a circadian disorder characterized by a lack of a clear sleep-wake pattern. The disorder has yet to be fully understood from pathophysiologic perspective. Treatments are available, but there is a need for development of novel interventions. The goal of this article is to focus on multiple aspects of ISWRD.