Sleep and suicidality in psychotic patients

The Mediating Role of Insomnia Severity in the Relationship Between Anxiety Symptoms and Suicidal Ideation: A Real-World Study in a Psychiatric Inpatient Setting

ABSTRACT

Insomnia and anxiety symptoms are independent clinical variables involved in suicidal ideation in psychiatric inpatients. In this article, we investigated the relationship among insomnia severity, severity of anxiety symptoms, and suicidal ideation in a sample of psychiatric inpatients with severe mental disorders. We used a mediation model considering insomnia severity as the possible mediator of the relationship between anxiety severity and suicidal ideation. We administered the Columbia Suicide Severity Rating Scale, the Insomnia Severity Index, and the Hamilton Anxiety Rating Scale to 116 consecutive inpatients to the psychiatric unit of Sant'Andrea Hospital in Rome. The effect of anxiety symptoms was mediated by insomnia severity; patients who perceive higher anxiety symptoms were more likely to experience higher levels of insomnia and, thus, higher suicidal ideation intensity. Results showed the importance of assessing and treating both insomnia and anxiety in clinical practice.

Sleep and circadian rhythms in adolescents with attempted suicide

Sleep and circadian rhythm disorders are very common in adolescents and have been linked to suicidal ideation. However, little is known about adolescent sleep before a suicide attempt (SA). The objectives of this study were to compare the sleep of adolescents aged 13 to 18 over a period of 4 weeks before a SA compared to a non-SA group, then to analyze the association between sleep, support social and well-being based on information from validated questionnaires. In 2015, 250 adolescents were included, 55 were recruited the day after a SA in French hospitals (before SA evaluations were retrospective). Logistic regression analyzes showed that during school days, bedtime was equivalent in both groups, but sleep onset latency was significantly longer in SA (86 min vs. 52 min, p = 0.016), and wake-up time was earlier (6 h 22 vs. 6 h 47, p = 0.002), resulting in a shorter total sleep time of 44 min (OR = 0.76, CI 95% [0.61-0.93]) the month preceding SA. Adolescents with longer sleep time performed better on perceived psychological well-being (p = 0.005), relationship with parents (p = 0.011) and school environment (p < 0.001). Results indicate a significant change in the quantity and quality of adolescents' subjective sleep in the 4 weeks preceding SA requiring objective measures to study the predictive properties of sleep in SA.

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.

Objective sleep markers of suicidal behaviors in patients with psychiatric disorders: A systematic review and meta-analysis

Close relationships have been reported between sleep alterations and suicidal behaviors, nevertheless few studies used objective measures of sleep. Such objective markers would be interesting in clinical practice to better screen and prevent suicide. We conducted a systematic review and meta-analysis of published studies examining the relationship between sleep markers and suicidal behaviors using PubMed, Cochrane Library, and Web of Science databases. Actigraphy, polysomnography, and nocturnal EEG were considered. The qualitative analysis retained 15 original studies, including 1179 participants (939 with a psychiatric disorder), and 11 studies were included for the meta-analysis. Current suicidal behaviors were associated with a decreased total sleep time (TST) (SMD = -0.35, [95% CI: -0.66 to -0.04], p = 0.026, I² = 39.8%). The evaluation of possible moderators shows that age, gender, and depression scores had no effects on the random effect model. No significant differences were observed regarding sleep efficiency, REM latency, or percentage of REM sleep. In conclusion, among candidate objective markers, decreased total sleep time seems associated with suicidal behaviors and could be easily used to assess suicide risk. Alterations of regular sleep duration should invite healthcare professionals to screen the cause and propose sleep interventions to prevent suicide.

The Importance of Suicide Risk Formulation in Schizophrenia

Suicide is a cause of early mortality in nearly 5% of patients with schizophrenia, and 25-50% of patients with schizophrenia attempt suicide in their lifetime. Evidence points to numerous individual, clinical, social, and psychological risk factors for suicide in patients with schizophrenia. Although recognizing suicidal risk factors in schizophrenia is extremely important in suicidal risk assessment, we have recently witnessed a change in suicide risk management that shifts the focus from suicide risk assessment to suicide risk formulation. Suicide risk formulation is dependent on the data gathered in the suicide risk assessment and assigns a level of suicide risk that is indispensable for the choice of treatment and the management of patients with a high suicidal risk. In this article, we extend the suicide risk formulation model to patients with schizophrenia. Suicide risk formulation results from four different areas that help clinicians collect as much information as possible for the management of suicidal risk. The four distinct judgments comprise risk status (the risk relating to the specific group to which the patient belongs), risk state (the risk for the person compared with his baseline or another reference point in the course of his life), available resources (on whom the person can count during a crisis) and foreseeable events (which can exacerbate the crisis). In schizophrenia, the suicide risk formulation model allows the clinician to evaluate in depth the clinical context of the patient, the patient's own history and patient-specific opportunities for better choosing and applying suicide prevention strategies.

Lipid Pathology of the Corpus Callosum in Schizophrenia and the Potential Role of Abnormal Gene Regulatory Networks with Reduced Microglial Marker Expression

Structural changes in the corpus callosum have been reported in schizophrenia; however, the underlying molecular mechanism remains unclear. As the corpus callosum is high in lipid content, we analyzed the lipid contents of the corpora callosa from 15 patients with schizophrenia and 15 age- and sex-matched controls using liquid chromatography coupled to tandem mass spectrometry and identified lipid combinations associated with schizophrenia. Real-time quantitative polymerase chain reaction analyses using extended samples (schizophrenia, n = 95; control, n = 91) showed low expression levels of lipid metabolism-related genes and their potential upstream transcription factors in schizophrenia. Subsequent pathway analysis identified a gene regulatory network where nuclear factor of activated T cells 2 (NFATC2) is placed most upstream. We also observed low gene expression levels of microglial markers, inflammatory cytokines, and colony-stimulating factor 1 receptor (CSF1R), which is known to regulate the density of microglia, in the corpus callosum in schizophrenia. The interactions between CSF1R and several genes in the presently identified gene network originating from NFATC2 have been reported. Collectively, this study provides evidence regarding lipid abnormalities in the corpora callosa of patients with schizophrenia and proposes the potential role of impaired “NFATC2-relevant gene network-microglial axis” as its underlying mechanism.

Objective measurement of sleep, heart rate, heart rate variability, and physical activity in suicidality: A systematic review

BACKGROUND

Emerging literature suggests that the arousal and regulatory systems as measured by sleep-wakefulness, heart rate (HR) and heart rate variability (HRV) may be powerful objective warning signs of suicidality. However, there is no systematic literature review examining the association between objective measurements of these variables with suicide and suicidal behavior.

METHODS

A web-based, systematic literature search using PubMed and EMBASE was conducted for articles that measured sleep-wakefulness and HR/HRV quantitatively in association with suicide. Search results were limited to human subjects and articles published in peer-reviewed journals in English. There were no restrictions for age, sex, settings and durations of measurements, types of mental illnesses, or comorbidity.

RESULTS

Twenty-three studies were included in the current systematic review. Across the studies, consistent patterns of disturbed sleep-wakefulness such as greater sleep onset latency and lower sleep efficiency were related to suicide. In addition, higher HR and lower variance of R-R intervals was an indicator of risk of suicide.

LIMITATIONS

Studies that used different equipment for sleep studies (i.e., polysomnography, electroencephalogram, actigraphy) were combined, and potential differences in their findings due to the different equipment were not considered.

CONCLUSIONS

Findings provide initial evidence for consistent patterns of sleep-wakefulness and HR/HRV possibly associated with suicidality; however, more studies are needed in order to identify the precise objective variables (e.g., sleep onset latency, high-frequency HRV), as well as time-varying patterns in these variables, that are related to acute suicide risk.

Association between suicide death and concordance with benzodiazepine treatment guidelines for anxiety and sleep disorders

OBJECTIVE

Guidelines for management of anxiety and sleep disorders emphasize antidepressant medications and/or psychotherapy as first/second-line and benzodiazepines as third-line treatments. We evaluated the association between suicide death and concordance with benzodiazepine guidelines.

METHODS

Retrospective case-control study of patients with anxiety and/or sleep disorders from health systems across 8 U.S. states within the Mental Health Research Network. Suicide death cases were matched to controls on year and health system. Appropriate benzodiazepine prescribing defined as: no monotherapy, no long duration, and/or age < 65 years. The association between guideline concordance and suicide death was evaluated, adjusting for diagnostic and treatment covariates.

RESULTS

Sample included 6960 patients with anxiety disorders (2363 filled benzodiazepine) and 6215 with sleep disorders (1237 filled benzodiazepine). Benzodiazepine guideline concordance was associated with reduced odds for suicide in patients with anxiety disorders (OR = 0.611, 95% CI = 0.392-0.953, p = 0.03) and was driven by shorter duration of benzodiazepine use with concomitant psychotherapy or antidepressant medication. The association of benzodiazepine guideline concordance with suicide death did not meet statistical significance in the sleep disorder group (OR = 0.413, 95% CI = 0.154-1.11, p = 0.08).

CONCLUSIONS

We found reduced odds for suicide in those with anxiety disorders who filled benzodiazepines in short-moderate duration with concomitant psychotherapy or antidepressant treatment.

Variables associated with reductions in insomnia severity among acutely suicidal patients receiving brief cognitive behavioral therapy for suicide prevention

INTRODUCTION

This study compared changes in sleep disturbance over time across brief cognitive behavioral therapy for suicide prevention and treatment as usual and examined the mechanisms that link sleep disturbance with several suicide risk factors.

METHOD

Active duty U.S. Army soldiers (N = 152) completed a randomized controlled trial to test the efficacy of brief cognitive behavioral therapy (n = 76) or treatment as usual (n = 76). Six assessments of insomnia symptoms, hopelessness, coping, and suicide beliefs were tracked over 24 months.

RESULTS

Brief cognitive behavioral therapy patients reported a significant decrease in sleep disturbance symptoms over time while treatment as usual patients did not. These improvements were initially observed during treatment and carried over through 12-months. Changes in sleep disturbance predicted changes in suicide risk. Longitudinal growth modeling was used to assess potential mechanisms of this effect. Results suggested that changes in cognitive flexibility, as defined by measures of hopelessness and suicide beliefs, predicted change in sleep disturbance symptoms. These relationships did not differ across treatment groups.

LIMITATIONS

The participants were active duty military personnel. Therefore, the results may not generalize to other patient populations. A greater number of assessment periods in closer proximity as well as additional measures of constructs of interest would have improved the internal validity of this study.

CONCLUSIONS

Brief cognitive behavioral therapy significantly reduces sleep disturbance and suicide risk. Changes in cognitive flexibility, in part, explain change in sleep disturbance across both treatments.

Short sleep duration and poor sleep quality predict next-day suicidal ideation: an ecological momentary assessment study

BACKGROUND

Sleep problems are a modifiable risk factor for suicidal thoughts and behaviors. Yet, sparse research has examined temporal relationships between sleep disturbance, suicidal ideation, and psychological factors implicated in suicide, such as entrapment. This is the first in-the-moment investigation of relationships between suicidal ideation, objective and subjective sleep parameters, and perceptions of entrapment.

METHODS

Fifty-one participants with current suicidal ideation completed week-long ecological momentary assessments. An actigraph watch was worn for the duration of the study, which monitored total sleep time, sleep efficiency, and sleep latency. Daily sleep diaries captured subjective ratings of the same sleep parameters, with the addition of sleep quality. Suicidal ideation and entrapment were measured at six quasi-random time points each day. Multi-level random intercept models and moderation analyses were conducted to examine the links between sleep, entrapment, and suicidal ideation, adjusting for anxiety and depression severity.

RESULTS

Analyses revealed a unidirectional relationship whereby short sleep duration (both objective and subjective measures), and poor sleep quality, predicted the higher severity of next-day suicidal ideation. However, there was no significant association between daytime suicidal ideation and sleep the following night. Sleep quality moderated the relationship between pre-sleep entrapment and awakening levels of suicidal ideation.

CONCLUSIONS

This is the first study to report night-to-day relationships between sleep disturbance, suicidal ideation, and entrapment. Findings suggest that sleep quality may alter the strength of the relationship between pre-sleep entrapment and awakening suicidal ideation. Clinically, results underscore the importance of assessing and treating sleep disturbance when working with those experiencing suicidal ideation.

A comparison of passive and active estimates of sleep in a cohort with schizophrenia

Sleep abnormalities are considered an important feature of schizophrenia, yet convenient and reliable sleep monitoring remains a challenge. Smartphones offer a novel solution to capture both self-reported and objective measures of sleep in schizophrenia. In this three-month observational study, 17 subjects with a diagnosis of schizophrenia currently in treatment downloaded Beiwe, a platform for digital phenotyping, on their personal Apple or Android smartphones. Subjects were given tri-weekly ecological momentary assessments (EMAs) on their own smartphones, and passive data including accelerometer, GPS, screen use, and anonymized call and text message logs was continuously collected. We compare the in-clinic assessment of sleep quality, assessed with the Pittsburgh Sleep Questionnaire Inventory (PSQI), to EMAs, as well as sleep estimates based on passively collected accelerometer data. EMAs and passive data classified 85% (11/13) of subjects as exhibiting high or low sleep quality compared to the in-clinic assessments among subjects who completed at least one in-person PSQI. Phone-based accelerometer data used to infer sleep duration was moderately correlated with subject self-assessment of sleep duration (r = 0.69, 95% CI 0.23–0.90). Active and passive phone data predicts concurrent PSQI scores for all subjects with mean average error of 0.75 and future PSQI scores with a mean average error of 1.9, with scores ranging from 0–14. These results suggest sleep monitoring via personal smartphones is feasible for subjects with schizophrenia in a scalable and affordable manner.

Smartphones may one-day offer accessible, clinically-useful insights into schizophrenia patients’ sleep quality. Despite the clinical relevance of sleep to disease severity, monitoring technologies still evade convenience and reliability. In search of a preferential method, a group of Harvard University researchers led by Patrick Staples investigated the validity of data collected via patients’ own mobile phones. The team, with a cohort of 17 schizophrenia patients, compared the quality of data produced by smartphone sensors and smartphone-delivered questionnaires to that of an in-clinic evaluation. The results significantly showed that smartphone monitoring could generate information that approached the accuracy of in-clinic assessments. The team noted some areas for improvement; however, this study provides convincing justifications for further research into this non-invasive, low-cost, scalable method to monitor the sleep quality of schizophrenic patients.

Objectively Assessed Sleep Variability as an Acute Warning Sign of Suicidal Ideation in a Longitudinal Evaluation of Young Adults at High Suicide Risk

OBJECTIVE

Young adults attempt suicide at disproportionately high rates relative to other groups and demonstrate high rates of sleep disturbance. No study has yet prospectively evaluated disturbed sleep as an acute indicator of risk using an objective index of sleep. We investigated objective and subjective parameters of disturbed sleep as a warning sign of suicidal ideation among young adults over an acute period.

METHODS

A longitudinal study across a 21-day observation period and 3 time points. Fifty of 4,847 participants (aged 18-23 years) were prescreened from a university undergraduate research pool (February 2007-June 2008) on the basis of suicide attempt history and recent suicidal ideation. Actigraphic and subjective sleep parameters were evaluated as acute predictors of suicidal ideation (Beck Scale for Suicide Ideation), with adjustment for baseline symptoms. Hierarchical regression analyses were employed to predict residual change scores.

RESULTS

Ninety-six percent of participants (n = 48) endorsed a suicide attempt history. Mean actigraphy values revealed objectively disturbed sleep parameters; 78% (n = 39) and 36% (n = 18) endorsed clinically significant insomnia and nightmares, respectively. When results were controlled for baseline suicidal and depressive symptoms, actigraphic and subjective sleep parameters predicted suicidal ideation residual change scores at 7- and 21-day follow-ups (P < .001). Specifically, actigraphy-defined variability in sleep timing, insomnia, and nightmares predicted increases in suicidal ideation (P < .05). In a test of competing risk factors, sleep variability outperformed depressive symptoms in the longitudinal prediction of suicidal ideation across time points (P < .05).

CONCLUSIONS

Objectively and subjectively measured sleep disturbances predicted acute suicidal ideation increases in this population, independent of depressed mood. Self-reported insomnia and nightmares and actigraphically assessed sleep variability emerged as acute warning signs of suicidal ideation. These findings highlight the potential utility of sleep as a proposed biomarker of suicide risk and a therapeutic target.

Examining the role of psychological factors in the relationship between sleep problems and suicide

We sought to conduct the first systematic review of empirical evidence investigating the role of psychological factors in the relationship between sleep problems and suicidal thoughts and behaviours. Twelve studies were identified which examined psychological factors grouped into four categories of cognitive appraisals, psychosocial factors, emotion regulation strategies, and risk behaviours. Although there was substantial heterogeneity across studies with respect to measurement, sampling, and analysis, preliminary evidence indicated that negative cognitive appraisals, perceived social isolation, and unhelpful emotion regulation strategies may contribute to the association between sleep problems and suicidal thoughts and behaviours. Given that findings in this area are currently restricted to studies with cross-sectional designs, the directionality of the interrelationships between these psychological factors, sleep problems and suicidality, remains unclear. We integrate the findings of our review with contemporary psychological models of suicidal behaviour to develop a clear research agenda. Identified pathways should now be tested with longitudinal and experimental designs. In addition, a more thorough investigation of the complexities of sleep, psychological factors, and suicidal thoughts and behaviours is crucial for the development of targeted psychological interventions.

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Systematic review of the role of psychological factors in sleep/suicide relationships

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Review findings integrated with suicide theory to define a clear research agenda.

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Reliance on cross-sectional designs limits interpretation of directionality of pathways.

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Identified pathways should be investigated with longitudinal and experimental designs.

Sleep architecture parameters as a putative biomarker of suicidal ideation in treatment-resistant depression

BACKGROUND

Disturbed sleep may confer risk for suicidal behaviors. Polysomnographic (PSG) sleep parameters have not been systematically evaluated in association with suicidal ideation (SI) among individuals with treatment-resistant depression (TRD).

METHODS

This secondary data analysis included 54 TRD individuals (N=30 with major depressive disorder (MDD) and N=24 with bipolar depression (BD)). PSG sleep parameters included Sleep Efficiency (SE), Total Sleep Time (TST), Wakefulness After Sleep Onset (WASO), REM percent/latency, and non-REM (NREM) Sleep Stages 1-4. The Hamilton Depression Rating Scale (HAM-D) was used to group participants according to presence or absence of SI. Sleep abnormalities were hypothesized among those with current SI. ANOVA analyses were conducted before (Model 1) and after adjusting for depression (Model 2) and diagnostic variables (Model 3).

RESULTS

Significant differences in PSG parameters were observed in Model 1; those with SI had less NREM Stage 4 sleep (p<.05). After adjusting for central covariates, Models 2 and 3 revealed significantly less NREM Stage 4 sleep, lower SE (P<.05), and higher WASO (P<.05) among those with SI. BD participants with SI also had less NREM Stage 4 and more NREM Stage 1 sleep.

LIMITATIONS

1) a predominantly white sample; 2) exclusion of imminent suicide risk; 3) concomitant mood stabilizer use among BD patients; and 4) single-item SI assessment.

CONCLUSIONS

Independent of depression severity, SI was associated with less NREM Stage 4 sleep, and higher nocturnal wakefulness across diagnostic groups. Sleep may warrant further investigation in the pathogenesis of suicide risk, particularly in TRD, where risk may be heightened.

Sleep and mental disorders: A meta-analysis of polysomnographic research

Investigating sleep in mental disorders has the potential to reveal both disorder-specific and transdiagnostic psychophysiological mechanisms. This meta-analysis aimed at determining the polysomnographic (PSG) characteristics of several mental disorders. Relevant studies were searched through standard strategies. Controlled PSG studies evaluating sleep in affective, anxiety, eating, pervasive developmental, borderline and antisocial personality disorders, attention-deficit-hyperactivity disorder (ADHD), and schizophrenia were included. PSG variables of sleep continuity, depth, and architecture, as well as rapid-eye movement (REM) sleep were considered. Calculations were performed with the "Comprehensive Meta-Analysis" and "R" software. Using random effects modeling, for each disorder and each variable, a separate meta-analysis was conducted if at least 3 studies were available for calculation of effect sizes as standardized means (Hedges' g). Sources of variability, that is, sex, age, and mental disorders comorbidity, were evaluated in subgroup analyses. Sleep alterations were evidenced in all disorders, with the exception of ADHD and seasonal affective disorders. Sleep continuity problems were observed in most mental disorders. Sleep depth and REM pressure alterations were associated with affective, anxiety, autism and schizophrenia disorders. Comorbidity was associated with enhanced REM sleep pressure and more inhibition of sleep depth. No sleep parameter was exclusively altered in 1 condition; however, no 2 conditions shared the same PSG profile. Sleep continuity disturbances imply a transdiagnostic imbalance in the arousal system likely representing a basic dimension of mental health. Sleep depth and REM variables might play a key role in psychiatric comorbidity processes. Constellations of sleep alterations may define distinct disorders better than alterations in 1 single variable. (PsycINFO Database Record

Sleep Disturbances in Schizophrenia

Sleep disturbances are prevalent in patients with schizophrenia and play a critical role in the morbidity and mortality associated with the illness. Subjective and objective assessments of sleep in patients with schizophrenia have identified certain consistent findings. Findings related to the sleep structure abnormalities have shown correlations with important clinical aspects of the illness. Disruption of specific neurotransmitter systems and dysregulation of clock genes may play a role in the pathophysiology of schizophrenia-related sleep disturbances. Antipsychotic medications play an important role in the treatment of sleep disturbances in these patients and have an impact on their sleep structure.

Sleep disturbances as an evidence-based suicide risk factor

Increasing research indicates that sleep disturbances may confer increased risk for suicidal behaviors, including suicidal ideation, suicide attempts, and death by suicide. Despite increased investigation, a number of methodological problems present important limitations to the validity and generalizability of findings in this area, which warrant additional focus. To evaluate and delineate sleep disturbances as an evidence-based suicide risk factor, a systematic review of the extant literature was conducted with methodological considerations as a central focus. The following methodologic criteria were required for inclusion: the report (1) evaluated an index of sleep disturbance; (2) examined an outcome measure for suicidal behavior; (3) adjusted for presence of a depression diagnosis or depression severity, as a covariate; and (4) represented an original investigation as opposed to a chart review. Reports meeting inclusion criteria were further classified and reviewed according to: study design and timeframe; sample type and size; sleep disturbance, suicide risk, and depression covariate assessment measure(s); and presence of positive versus negative findings. Based on keyword search, the following search engines were used: PubMed and PsycINFO. Search criteria generated N = 82 articles representing original investigations focused on sleep disturbances and suicide outcomes. Of these, N = 18 met inclusion criteria for review based on systematic analysis. Of the reports identified, N = 18 evaluated insomnia or poor sleep quality symptoms, whereas N = 8 assessed nightmares in association with suicide risk. Despite considerable differences in study designs, samples, and assessment techniques, the comparison of such reports indicates preliminary, converging evidence for sleep disturbances as an empirical risk factor for suicidal behaviors, while highlighting important, future directions for increased investigation.

Association of poor subjective sleep quality with risk for death by suicide during a 10-year period: a longitudinal, population-based study of late life

IMPORTANCE

Older adults have high rates of sleep disturbance, die by suicide at disproportionately higher rates compared with other age groups, and tend to visit their physician in the weeks preceding suicide death. To our knowledge, to date, no study has examined disturbed sleep as an independent risk factor for late-life suicide.

OBJECTIVE

To examine the relative independent risk for suicide associated with poor subjective sleep quality in a population-based study of older adults during a 10-year observation period.

DESIGN, SETTING, AND PARTICIPANTS

A longitudinal case-control cohort study of late-life suicide among a multisite, population-based community sample of older adults participating in the Established Populations for Epidemiologic Studies of the Elderly. Of 14 456 community older adults sampled, 400 control subjects were matched (on age, sex, and study site) to 20 suicide decedents.

MAIN OUTCOMES AND MEASURES

Primary measures included the Sleep Quality Index, the Center for Epidemiologic Studies-Depression Scale, and vital statistics.

RESULTS

Hierarchical logistic regressions revealed that poor sleep quality at baseline was significantly associated with increased risk for suicide (odds ratio [OR], 1.39; 95% CI, 1.14-1.69; P < .001) by 10 follow-up years. In addition, 2 sleep items were individually associated with elevated risk for suicide at 10-year follow-up: difficulty falling asleep (OR, 2.24; 95% CI, 1.27-3.93; P < .01) and nonrestorative sleep (OR, 2.17; 95% CI, 1.28-3.67; P < .01). Controlling for depressive symptoms, baseline self-reported sleep quality was associated with increased risk for death by suicide (OR, 1.30; 95% CI, 1.04-1.63; P < .05).

CONCLUSIONS AND RELEVANCE

Our results indicate that poor subjective sleep quality is associated with increased risk for death by suicide 10 years later, even after adjustment for depressive symptoms. Disturbed sleep appears to confer considerable risk, independent of depressed mood, for the most severe suicidal behaviors and may warrant inclusion in suicide risk assessment frameworks to enhance detection of risk and intervention opportunity in late life.

The timing of deliberate self harm behaviour

Objectives: To critically review the scientific literature relating to the timing of deliberate self harm behaviour and completed suicide.

Method: A literature search of the Medline and CINAHL databases from 1970-2002 was performed, using deliberate self harm, overdose, self poisoning, suicide, parasuicide, and time, timing, day, week, month and season as key words. Relevant secondary references were retrieved and hand searching of important journals was done.

Results: The time of day of non-fatal self harm shows a marked diurnal variation, with an evening peak that is related to non-violent episodes, concomitant alcohol use, and a younger age. It is not conclusively linked to the degree of suicidal intent or particular psychiatric diagnoses. Completed suicides more commonly occur earlier in the day, at the beginning of the week and during springtime, but show no overall increase during many national events and holidays.

Conclusions: Circadian biological mechanisms involving the serotonin-melatonin axis, Cortisol secretion and sleep abnormalities appear to be implicated. Psychosocial explanations for these epidemiological findings include alcohol use, a sense of personal isolation and the ‘broken promise’ effect.

Subjective and objective sleep and self-harm behaviors in young children: a general population study

Significant association between sleep disturbances and suicidal ideation and/or attempts is reported in adults and adolescents. However, there is paucity of studies exploring the association between sleep and self-harm behaviors (SHB) in young children and are limited to only subjective sleep measures. We examined the association between SHB and both subjective and objective sleep in a population-based sample of 5-12 yr old. Parents of every student in 3 local school (K-5) districts (n=7312) was sent a screening questionnaire. Randomly selected children from this sample underwent a comprehensive history, physical examination, a 9-h overnight polysomnogram and completed several questionnaires. Among the final sample (n=693), 27 children had SHB with adjusted prevalence of 3%. There was no difference in age, gender, obesity, or socioeconomic status in subjects with or without SHB. Significantly more children with SHB had subjective sleep difficulty and depression. Difficulty maintaining sleep and frequent nightmares were associated with SHB independent of depression or demographics. Polysomnographic %REM-sleep was significantly higher in the SHB group after adjusting for demographics and depression. These data indicate that parent reported sleep disturbances are independently associated with SHB. It is possible that higher REM-sleep is a non-invasive biomarker for risk of self-harm behaviors in young children.

Sleep as a biomarker for depression

Sleep is a complex biological process that involves cyclic changes of brain activity. The smooth transition between wakefulness and sleep and cyclic succession of sleep stages depend on the function of numerous neurotransmitters that reciprocally influence each other. For this reason sleep is a very sensitive biomarker of brain functioning. This article provides an overview of sleep changes in depression, mechanisms involved in sleep regulation and pathophysiology underlying depression, studies on sleep as a biomarker for depression, effects of antidepressants on sleep EEG, and studies in depression with the use of quantitative sleep EEG analysis. Research on sleep in depression has provided several valuable biomarkers that are related to increased risk for depression, show worsening during depressive episode, and are related to treatment outcome and relapse risk during remission phase. Among many sleep parameters, increased REM density and diminished delta sleep ratio deserve special interest. Sleep studies are also an important research tool for antidepressant drug development. However, due to sensitivity of sleep parameters to pharmacological interventions, the patients have to be investigated before the start of pharmacological treatment or after washout from the antidepressant drug, to obtain reliable data on disease-related biological processes from polysomnography.

Psychiatric disorders and sleep

There is growing experimental evidence that the relationship between psychiatric disorders and sleep is complex and includes bidirectional causation. This article provides the evidence that supports this point of view, reviewing data on sleep disturbances seen in patients with psychiatric disorders as well as data on the impact of sleep disturbances on psychiatric conditions. Although much has been learned about the psychiatric disorders-sleep relationship, additional research is needed to better understand the relationship. Such work promises to improve comprehension of these phenomena and lead to better treatment for the many patients with sleep disorders and psychiatric disorders.

Sleep problems outperform depression and hopelessness as cross-sectional and longitudinal predictors of suicidal ideation and behavior in young adults in the military

BACKGROUND

Sleep problems appear to represent an underappreciated and important warning sign and risk factor for suicidal behaviors. Given past research indicating that disturbed sleep may confer such risk independent of depressed mood, in the present report we compared self-reported insomnia symptoms to several more traditional, well-established suicide risk factors: depression severity, hopelessness, PTSD diagnosis, as well as anxiety, drug abuse, and alcohol abuse symptoms.

METHODS

Using multiple regression, we examined the cross-sectional and longitudinal relationships between insomnia symptoms and suicidal ideation and behavior, controlling for depressive symptom severity, hopelessness, PTSD diagnosis, anxiety symptoms, and drug and alcohol abuse symptoms in a sample of military personnel (N=311).

RESULTS

In support of a priori hypotheses, self-reported insomnia symptoms were cross-sectionally associated with suicidal ideation, even after accounting for symptoms of depression, hopelessness, PTSD diagnosis, anxiety symptoms and drug and alcohol abuse. Self-reported insomnia symptoms also predicted suicide attempts prospectively at one-month follow up at the level of a non-significant trend, when controlling for baseline self-reported insomnia symptoms, depression, hopelessness, PTSD diagnosis and anxiety, drug and alcohol abuse symptoms. Insomnia symptoms were unique predictors of suicide attempt longitudinally when only baseline self-reported insomnia symptoms, depressive symptoms and hopelessness were controlled.

LIMITATIONS

The assessment of insomnia symptoms consisted of only three self-report items. Findings may not generalize outside of populations at severe suicide risk.

CONCLUSIONS

These findings suggest that insomnia symptoms may be an important target for suicide risk assessment and the treatment development of interventions to prevent suicide.

Sleep disturbances and suicidality: a common association to look for in clinical practise and preventive care

Suicidality and suicide has been associated with many risk factors, while recent clinical and epidemiological studies increasingly point to a potential link between sleep loss or sleep disturbances and suicidality. This review on studies of sleep disturbances associated with suicidality, i.e., suicidal ideation, suicide attempt and completed suicide suggests a frequent association especially with insomnia and nightmares but also hypersomnia and sleep panic attacks. In suicidal insomniacs with comorbid psychiatric disorders, there is some evidence for an even independent predictive nature of sleep problems for suicidality. Considerations on the shared neurobiology, risk assessment and treatment options complement the overview. Thus, sleep disturbances may qualify as an individual treatable target of personalised medicine in the clinical routine as well as in suicide prevention programmes. A more detailed assessment of sleep problems and identification of specific risk domains in primary or secondary prevention of suicidality seem to be a future area of high importance.

Sleep disturbances and suicidal ideation in sleep medical center patients

OBJECTIVE

The purpose of this investigation was two-fold: first, we examined associations between suicidal ideation, maladaptive sleep patterns and abnormal sleep behaviors in a sleep center population, an understudied population in the domain of suicide research; and then, we explored whether significant associations remained after accounting for the possible influence of depressive symptoms.

METHOD

Data were analyzed from intake information obtained from 1584 adult patients presenting at a community-based private sleep medical center. The sample was parsed into a Suicidal Ideation (SI) group (N=211) and No Suicidal Ideation (NSI) group (N=1373). Comparisons of these groups were made on measures of self-reported sleep complaints, habits, and behaviors, suicidal ideation, depressive symptoms, and associated psychopathology.

RESULTS

Approximately 13% of participants reported suicidal ideation. Clinically significant suicidal ideation was present in 4.5% of the sample. Compared to the NSI group, the SI group showed a pervasive pattern of significantly greater frequency or severity of sleep problems in areas of insomnia, nightmares and other parasomnia behaviors, poor sleep quality, and sleep-related psychophysiologic conditioning as well as worse sleep-related impairment and quality of life. Several relationships were significant after controlling for depressive symptoms.

DISCUSSION

Suicidal ideation was consistently associated with a broad array of sleep complaints, even when controlling for level of depressive symptoms. As these self-reported sleep disturbances are treatable sleep disorders, future research should examine the efficacy of sleep and behavioral medicine for reducing the risk of suicidal ideation.

Insomnia severity is an indicator of suicidal ideation during a depression clinical trial

OBJECTIVE

Insomnia has been linked to suicidal ideas and suicide death in cross-sectional and longitudinal population-based studies. A link between insomnia and suicide has not been previously examined in the setting of a clinical trial. Herein we describe the relationship between insomnia and suicidal thinking during the course of a clinical trial for depression with insomnia.

METHODS

Sixty patients aged 41.5±12.5 years (2/3 women) with major depressive episode and symptoms of insomnia received open-label fluoxetine for 9 weeks and also received blinded, randomized eszopiclone 3mg or placebo at bedtime after the first week of fluoxetine. Insomnia symptoms were assessed with the Insomnia Severity Index (ISI), and suicidal ideation was assessed with The Scale for Suicide Ideation (SSI). Depression symptoms were assessed with the depressed mood item and the anhedonia item from the Hamilton Rating Scale for Depression-24 (HRSD24), as well as a sum score for all non-sleep and non-suicide items from the HRSD (HRSD20). Measurements were taken at baseline and weeks 1, 2, 4, 6, and 8. SSI was examined by generalized linear mixed models for repeated measures as the outcome of interest for all 60 participants with ISI and various mood symptoms as independent variables, with adjustment for age, gender, treatment assignment, and baseline SSI.

RESULTS

Higher levels of insomnia corresponded to significantly greater intensity of suicidal thinking (p<0.01). The depressed mood item of the HRSD, and the sum of the HRSD20, both corresponded to greater suicidal thinking (p<0.001). The anhedonia item did not correspond with suicidal thinking. When both ISI and the depressed mood item, or ISI and the anhedonia item, were included together in the same model, the ISI remained an independent predictor of suicidal thinking.

CONCLUSIONS

The results support the concept that insomnia may be a useful indicator for suicidal ideation and now extend this idea into clinical trials. Insomnia remains an independent indicator of suicidal ideation, even taking into account the core symptoms of depression such as depressed mood and anhedonia. The complaint of insomnia during a depression clinical trial might indicate that more direct questioning about suicide is warranted.

Completed suicide in schizophrenia: evidence from a case-control study

Suicide is the single major cause of death among patients with schizophrenia. Despite great efforts in the prevention of such deaths, suicide rates have remained alarming, pointing to the need for a better understanding of the phenomenon. The present sample comprised 20 male patients with schizophrenia who committed suicide and who were investigated retrospectively for a large number of characteristics. Controls were 20 living patients with schizophrenia. The results suggest that suicide attempts, hopelessness and self-devaluation were the three variables most strongly associated with completed suicide. However, a number of variables were identified which may constitute risk factors, some of which have not been identified in the past: agitation and motor restlessness (OR = 3.66; 95%CI = 0.95/14.02), self-devaluation (OR = 28.49; 95%CI = 3.15/257.40), hopelessness (OR = 51.00; 95%CI = 7.56-343.72), insomnia (OR = 12.66; 95%CI = 0.95/14.02), mental disintegration (OR = 3.66; 95%CI = 0.95/14.02), and suicide attempt (OR = 3.66; 95%CI = 1.40/114.41). Poor adherence to medications was also predictive of completed suicide in our sample of schizophrenia patients, primarily because the suicide victims showed very low adherence.

Sleep disturbances and suicide risk: A review of the literature

A growing body of research indicates that sleep disturbances are associated with suicidal ideation and behaviors. This article (1) provides a critical review of the extant literature on sleep and suicidality and (2) addresses shared underlying neurobiological factors, biological and social zeitgebers, treatment implications, and future directions for research. Findings indicate that suicidal ideation and behaviors are closely associated with sleep complaints, and in some cases, this association exists above and beyond depression. Several cross-sectional investigations indicate a unique association between nightmares and suicidal ideation, whereas the relationship between insomnia and suicidality requires further study. Underlying neurobiological factors may, in part, account for the relationship between sleep and suicide. Serotonergic neurotransmission appears to play a critical role in both sleep and suicide. Finally, it remains unclear whether or not sleep-oriented interventions may reduce risk for suicidal behaviors. Unlike other suicide risk factors, sleep complaints may be particularly amenable to treatment. As a warning sign, disturbances in sleep may thus be especially useful to research and may serve as an important clinical target for future suicide intervention efforts.

Suicide risk in schizophrenia: learning from the past to change the future

Suicide is a major cause of death among patients with schizophrenia. Research indicates that at least 5-13% of schizophrenic patients die by suicide, and it is likely that the higher end of range is the most accurate estimate. There is almost total agreement that the schizophrenic patient who is more likely to commit suicide is young, male, white and never married, with good premorbid function, post-psychotic depression and a history of substance abuse and suicide attempts. Hopelessness, social isolation, hospitalization, deteriorating health after a high level of premorbid functioning, recent loss or rejection, limited external support, and family stress or instability are risk factors for suicide in patients with schizophrenia. Suicidal schizophrenics usually fear further mental deterioration, and they experience either excessive treatment dependence or loss of faith in treatment. Awareness of illness has been reported as a major issue among suicidal schizophrenic patients, yet some researchers argue that insight into the illness does not increase suicide risk. Protective factors play also an important role in assessing suicide risk and should also be carefully evaluated. The neurobiological perspective offers a new approach for understanding self-destructive behavior among patients with schizophrenia and may improve the accuracy of screening schizophrenics for suicide. Although, there is general consensus on the risk factors, accurate knowledge as well as early recognition of patients at risk is still lacking in everyday clinical practice. Better knowledge may help clinicians and caretakers to implement preventive measures. This review paper is the result of a joint effort between researchers in the field of suicide in schizophrenia. Each expert provided a brief essay on one specific aspect of the problem. This is the first attempt to present a consensus report as well as the development of a set of guidelines for reducing suicide risk among schizophrenia patients.

Neurobiology of depression in children and adolescents

This article reviews classical and updated studies of the neurobiology of depressive disorders in children and adolescents. Most studies of childhood and adolescent depression and suicide have followed up the observations and methods used in studies in adults. These studies include neuroendocrine studies, which particularly look at the hypothalamic-pituitary-adrenal axis, the serotonergic system, peripheral blood and cerebrospinal fluid biologic markers, genetics, gene-environment interactions and sleep studies, and neuroimaging and postmortem studies, although in these areas the number of studies is limited.

Sleep and youth suicidal behavior: a neglected field

PURPOSE OF REVIEW

Sleep undergoes substantial changes during adolescence and suicide risk begins to increase during this period as well. This review focuses on recent literature on the relationship between sleep and suicidal behavior and proposes directions for future research.

RECENT FINDINGS

Adolescent sleep is characterized by widespread sleep restriction, irregular sleep schedules, daytime sleepiness, and elevated risk for sleep disturbances. More research on adolescent sleep and psychosocial impairment, psychiatric disorders, and suicidal behavior has been conducted. Suicidal psychiatric patients had more sleep disturbances including insomnia, hypersomnia, or nightmares than nonsuicidal patients. Shorter rapid eye movement latency and increased rapid eye movement activity have been noted to be a marker of suicidality in psychiatric patients. Epidemiological studies have demonstrated that insomnia, nightmares, and sleep insufficiency are associated with elevated risk for suicide. Although the link between insomnia and suicidal behavior appears to be mediated by depression, existing data suggest an independent predictive role of nightmares in future suicidal behavior.

SUMMARY

Sleep loss or disturbances are likely to signal an increased risk of future suicidal action in adolescents. Large-scale prospective studies and neurobiological studies are needed for a better understanding of the complex relationship between sleep, psychopathology, and youth suicidal behavior.

Alteration of sleep microstructure in psychiatric disorders

Macrostructure describes the temporal organization of sleep based on successive epochs of conventional length, while microstructure, which is analyzed on the basis of the scoring of phasic events, provides additional important dynamic characteristics in the evaluation of both normal and pathological sleep processes. Relationships between sleep, sleep disorders, and psychiatric disorders are quite complex, and it clearly appears that both the macrostructure and the microstructure of sleep are valuable physiologically and clinically. Psychiatric patients often complain about their sleep, and they may show sleep abnormalities that increase with the severity of their illness. Changes in the occurrence and frequency of phasic events during sleep may be associated with specific psychiatric disorders, and may provide valuable information for both diagnosis and prognosis of these disorders.

Older schizophrenia patients have more disrupted sleep and circadian rhythms than age-matched comparison subjects

Patient reports and laboratory studies suggest schizophrenia patients have disrupted sleep across age groups. Studies have not compared overall sleep/wake patterns or circadian (24-h) activity rhythms of older community dwelling schizophrenia patients to matched comparison subjects. This study examined whether older schizophrenia patients had more disrupted sleep/wake patterns and circadian activity rhythms than age- and gender-matched normal comparison subjects (NCS). Twenty-eight older schizophrenia patients and 28 age- and gender-matched NCS were studied with three days of continuous wrist actigraphy. Nighttime and daytime actigraphically estimated sleep and wake, circadian activity rhythms and light exposure patterns were compared with and without years of education as a covariate. Patients spent longer in bed, had more disrupted nighttime sleep, slept more during the day, and had less robust circadian rhythms of activity and light exposure compared to NCS. Differences persisted in education-adjusted analyses. Within patients, working was associated with improved sleep and circadian rhythms. Findings suggest the sleep and circadian rhythm disruption of older schizophrenia patients was more extensive than that of matched NCS suggesting patients' sleep disruption was above and beyond what is attributable to advanced age alone. A need exists to develop multicomponent interventions to address sleep difficulties specific to older schizophrenia patients.

Suicidal ideation in outpatients with chronic musculoskeletal pain: an exploratory study of the role of sleep onset insomnia and pain intensity

OBJECTIVES

Sleep disturbance, depression, and heightened risk of suicide are among the most clinically significant sequelae of chronic pain. While sleep disturbance is associated with suicidality in patients with major depression and is a significant independent predictor of completed suicide in psychiatric patients, it is not known whether sleep disturbance is associated with suicidal behavior in chronic pain. This exploratory study evaluates the importance of insomnia in discriminating suicidal ideation in chronic pain relative to depression severity and other pain-related factors.

METHODS

Fifty-one outpatients with non-cancer chronic pain were recruited. Subjects completed a pain and sleep survey, the Pittsburgh Sleep Quality Index, the Beck Depression Inventory, and the Multidimensional Pain Inventory. Subjects were classified as "suicidal ideators" or "non-ideators" based on their responses to BDI-Item 9 (Suicide). Bivariate analyses and multivariate discriminant function analyses were conducted.

RESULTS

Twenty-four percent reported suicidal ideation (without intent). Suicidal ideators endorsed higher levels of: sleep onset insomnia, pain intensity, medication usage, pain-related interference, affective distress, and depressive symptoms (P < 0.03). These 6 variables were entered into stepwise discriminant function analyses. Two variables predicted group membership: Sleep Onset Insomnia Severity and Pain Intensity, respectively. The discriminant function correctly classified 84.3% of the cases (P < 0.0001).

DISCUSSION

Chronic pain patients who self-reported severe and frequent initial insomnia with concomitant daytime dysfunction and high pain intensity were more likely to report passive suicidal ideation, independent from the effects of depression severity. Future research aimed at determining whether sleep disturbance is a modifiable risk factor for suicidal ideation in chronic pain is warranted.

REM sleep, dream variables and suicidality in depressed patients

To examine the relationship between the emotional quality of dreams, REM sleep variables and suicidal tendency in depressed individuals, 26 depressed volunteers (10 males and 16 females) were assessed with the Beck Depression Inventory (BDI) and the Hamilton Depression Rating Scale (HDRS), and underwent 3 nights of polysomnography. There was a significant negative correlation between suicidality scores and REM latency and a positive correlation between suicidality and REM percent. Suicidal subjects had a significantly shorter mean REM latency and a higher mean REM percentage than the non-suicidal subjects. As expected in normal subjects, 20 subjects had an increase in dream-like quality (DLQ) of REM reports between the first and second halves of the night. The six subjects with a negative DLQ difference also scored as suicidal. A reduction in dream-like quality of the REM content reports between the first and second halves of the night was found to be associated with suicidal tendency. The findings may indicate that these subjects fail to self-regulate mood and integrate affect into long-term memory networks during sleep. Theoretical and clinical implications of these findings in depression are discussed.

The ultimate resignation: suicide and search activity

This paper presents an integrative approach to suicidal behavior in terms of search activity concept. Search activity concept displays a broad and holistic approach to behavior, adaptation to environment, body resistance, brain amine metabolism, and REM-sleep functions. Search activity is defined as activity that is oriented to change the situation (or at least the subject's attitude to it) in the absence of a precise prediction of the outcome of such activity, but taking into consideration outcomes at all previous stages of activity. According to the proposed hypothesis, renunciation of search (a state opposed to search activity) leads to a feeling of helplessness, problem-solution deficits, inefficient coping, dreams that represent renunciation of search, and a drop in the activity of amines. All these factors further exacerbate the state of renunciation of search and elevate suicidal risk. In addition, the remnants of search activity are misdirected to self-defeating behaviors that increase mental pain and contribute to renunciation of search. This hypothesis integrates findings from a number of fields of study of suicidal behavior, resolves some paradoxes, suggests new lines of research, and raises suggestions for assessment and treatment of suicidal behavior.

Preliminary evidence of an association between increased REM density and poor antidepressant response to partial sleep deprivation

BACKGROUND

One night of total sleep deprivation or of late-night partial sleep deprivation (PSD) produces a temporary remission in approximately 40-60% of patients with major depressive disorder; however, little is known about polysomnography (PSG) characteristics of responders to these types of sleep deprivation (SD).

METHODS

Twenty-three unmedicated unipolar patients (17-item Hamilton Depression Rating Scale (HDRS17) >16) and 14 normal controls underwent 1 night of late-night PSD (awake after 3 a.m.) Subjects underwent baseline PSG and received the HDRS17 at standard times before and after PSD. Clinical response was defined as a reduction of >30% in the modified HDRS17 (omitting sleep and weight loss items) following PSD.

RESULTS

The 12 responders and 11 nonresponders did not differ from each other significantly on baseline HDRS17 or PSG variables. The only PSG variable correlating with percent decrease in modified HDRS17 was baseline REM density (Pearson's r=-0.52, n=23, P=0.01.) In other words, the lower the baseline REM density, the more robust the antidepressant response was.

LIMITATIONS

Subject numbers are relatively small.

CONCLUSIONS

Increased REM density, which reflects the number of rapid eye movements per epoch of REM sleep, may be a physiological marker for severity or poor prognosis in a variety of psychiatric disorders, including relapse in recovering alcoholics, suicidality in schizophrenia, and poor response to PSD or interpersonal psychotherapy in depression.

Biological predictors of suicidality in schizophrenia

The objective of this study was to determine whether polysomnographic rapid eye movement (REM) sleep abnormalities and cortisol response to the dexamethasone suppression test (DST) differentiate between schizophrenic patients with and without a history of suicidal behaviour. We assessed a sample of 96 schizophrenic in-patients at the end of a 2-week medication-free period with the DST, polysomnography, and an extensive clinical assessment battery. Patients exhibiting suicidal behaviour were significantly more likely to have increased total REM time and increased total REM activity. We found no significant relationship between suicidal behaviour and DST non-suppression. This study confirms a previous finding suggesting an association between REM sleep abnormalities and suicidal behaviour in schizophrenia. It is postulated that this observed association may be related to serotonergic dysfunction in schizophrenia.