Associations between obesity, a composite risk score for probable long COVID, and sleep problems in SARS-CoV-2 vaccinated individuals.

BACKGROUND: Preliminary data suggests that obesity might hasten the decline in mRNA vaccine-induced immunity against SARS-CoV-2. However, whether this renders individuals with obesity more susceptible to long COVID symptoms post-vaccination remains uncertain. Given sleep's critical role in immunity, exploring the associations between obesity, probable long COVID symptoms, and sleep disturbances is essential. METHODS: We analyzed data from a survey of 5919 adults aged 18 to 89, all of whom received two SARS-CoV-2 mRNA vaccinations. Participants were categorized into normal weight, overweight, and obesity groups based on ethnicity-specific BMI cutoffs. The probability of long COVID was evaluated using the Post-Acute Sequelae of SARS-CoV-2 (PASC) score, as our survey did not permit confirmation of acute SARS-CoV-2 infection through methods such as antibody testing. Additionally, sleep patterns were assessed through questionnaires. RESULTS: Participants with obesity exhibited a significantly higher adjusted odds ratio (OR) of having a PASC score of 12 or higher, indicative of probable long COVID in our study, compared to those with normal weight (OR: 1.55, 95% CI: 1.05, 2.28). No significant difference was observed for overweight individuals (OR: 0.92 [95% CI: 0.63, 1.33]). Both obesity and probable long COVID were associated with increased odds of experiencing a heightened sleep burden, such as the presence of obstructive sleep apnea or insomnia (P < 0.001). However, no significant interaction between BMI and probable long COVID status was found. CONCLUSIONS: Even post-vaccination, individuals with obesity may encounter a heightened risk of experiencing prolonged COVID-19 symptoms. However, confirming our observations necessitates comprehensive studies incorporating rigorous COVID infection testing, such as antibody assays - unavailable in our anonymous survey. Additionally, it is noteworthy that the correlation between probable long COVID and sleep disturbances appears to be independent of BMI.

Nightmare frequency is a risk factor for suicidal ideation during the COVID-19 pandemic.

The association between nightmare frequency (NMF) and suicidal ideation (SI) is well known, yet the impact of the COVID-19 pandemic on this relation is inconsistent. This study aimed to investigate changes in NMF, SI, and their association during the COVID-19 pandemic. Data were collected in 16 countries using a harmonised questionnaire. The sample included 9328 individuals (4848 women; age M[SD] = 46.85 [17.75] years), and 17.60% reported previous COVID-19. Overall, SI was significantly 2% lower during the pandemic vs. before, and this was consistent across genders and ages. Most countries/regions demonstrated decreases in SI during this pandemic, with Austria (-9.57%), Sweden (-6.18%), and Bulgaria (-5.14%) exhibiting significant declines in SI, but Italy (1.45%) and Portugal (2.45%) demonstrated non-significant increases. Suicidal ideation was more common in participants with long-COVID (21.10%) vs. short-COVID (12.40%), though SI did not vary by COVID-19 history. Nightmare frequency increased by 4.50% during the pandemic and was significantly higher in those with previous COVID-19 (14.50% vs. 10.70%), during infection (23.00% vs. 8.10%), and in those with long-COVID (18.00% vs. 8.50%). The relation between NMF and SI was not significantly stronger during the pandemic than prior (rs = 0.18 vs. 0.14; z = 2.80). Frequent nightmares during the pandemic increased the likelihood of reporting SI (OR = 1.57, 95% CI 1.20-2.05), while frequent dream recall during the pandemic served a protective effect (OR = 0.74, 95% CI 0.59-0.94). These findings have important implications for identifying those at risk of suicide and may offer a potential pathway for suicide prevention.

Factor Analysis and Validation of the Disturbing Dream and Nightmare Severity Index in an Inpatient Sample.

STUDY OBJECTIVES: The Disturbing Dream and Nightmare Severity Index (DDNSI) has been used widely in research and clinical practice without psychometric evidence supporting its use in clinical samples. The present study aimed to explore and confirm the factor structure of the DDNSI in an inpatient sample. We also sought to test the measure's construct validity. METHODS: Two samples of U.S. inpatients including adult (N = 937) and adolescent (N = 274) participants provided data on nightmares (i.e. DDNSI), sleep quality (i.e. the Pittsburgh Sleep Quality Index) and related psychopathology symptoms (e.g. depression, posttraumatic stress disorder, anxiety). RESULTS: Exploratory and confirmatory factor analyses found the six original items of the DDNSI to load onto a single latent factor. CONCLUSIONS: The DDNSI was found to be a valid measure of nightmare frequency and distress, as it was significantly correlated with the items related to disturbing dreams, and the DDNSI was able to differentiate between nightmares and psychopathology symptoms. Though this research comes nearly two decades after the initial creation and use of the DDNSI, it provides a foundation for the scientific rigor of previous and future studies on nightmares using the DDNSI.

Dream-enactment behaviours during the COVID-19 pandemic: an international COVID-19 sleep study.

There has been increasing concern about the long-term impact of coronavirus disease 2019 (COVID-19) as evidenced by anecdotal case reports of acute-onset parkinsonism and the polysomnographic feature of increased rapid eye movement sleep electromyographic activity. This study aimed to determine the prevalence and correlates of dream-enactment behaviours, a hallmark of rapid eye movement sleep behaviour disorder, which is a prodrome of α-synucleinopathy. This online survey was conducted between May and August 2020 in 15 countries/regions targeting adult participants (aged ≥18 years) from the general population with a harmonised structured questionnaire on sleep patterns and disorders, COVID-19 diagnosis and symptoms. We assessed dream-enactment behaviours using the Rapid Eye Movement Sleep Behaviour Disorder Single-Question Screen with an additional question on their frequency. Among 26,539 respondents, 21,870 (82.2%) answered all items that were analysed in this study (mean [SD] age 41.6 [15.8] years; female sex 65.5%). The weighted prevalence of lifetime and weekly dream-enactment behaviours was 19.4% and 3.1% and were found to be 1.8- and 2.9-times higher in COVID-19-positive cases, respectively. Both lifetime and weekly dream-enactment behaviours were associated with young age, male sex, smoking, alcohol consumption, higher physical activity level, nightmares, COVID-19 diagnosis, olfactory impairment, obstructive sleep apnea symptoms, mood, and post-traumatic stress disorder features. Among COVID-19-positive cases, weekly dream-enactment behaviours were positively associated with the severity of COVID-19. Dream-enactment behaviours are common among the general population during the COVID-19 pandemic and further increase among patients with COVID-19. Further studies are needed to investigate the potential neurodegenerative effect of COVID-19.

Sleep symptoms are essential features of long-COVID - Comparing healthy controls with COVID-19 cases of different severity in the international COVID sleep study (ICOSS-II).

Many people report suffering from post-acute sequelae of COVID-19 or "long-COVID", but there are still open questions on what actually constitutes long-COVID and how prevalent it is. The current definition of post-acute sequelae of COVID-19 is based on voting using the Delphi-method by the WHO post-COVID-19 working group. It emphasizes long-lasting fatigue, shortness of breath and cognitive dysfunction as the core symptoms of post-acute sequelae of COVID-19. In this international survey study consisting of 13,628 subjects aged 18-99 years from 16 countries of Asia, Europe, North America and South America (May-Dec 2021), we show that post-acute sequelae of COVID-19 symptoms were more prevalent amongst the more severe COVID-19 cases, i.e. those requiring hospitalisation for COVID-19. We also found that long-lasting sleep symptoms are at the core of post-acute sequelae of COVID-19 and associate with the COVID-19 severity when COVID-19 cases are compared with COVID-negative cases. Specifically, fatigue (61.3%), insomnia symptoms (49.6%) and excessive daytime sleepiness (35.8%) were highly prevalent amongst respondents reporting long-lasting symptoms after hospitalisation for COVID-19. Understanding the importance of sleep-related symptoms in post-acute sequelae of COVID-19 has a clinical relevance when diagnosing and treating long-COVID.

Associations between changes in habitual sleep duration and lower self-rated health among COVID-19 survivors: findings from a survey across 16 countries/regions.

BACKGROUND: Self-rated health (SRH) is widely recognized as a clinically significant predictor of subsequent mortality risk. Although COVID-19 may impair SRH, this relationship has not been extensively examined. The present study aimed to examine the correlation between habitual sleep duration, changes in sleep duration after infection, and SRH in subjects who have experienced SARS-CoV-2 infection. METHODS: Participants from 16 countries participated in the International COVID Sleep Study-II (ICOSS-II) online survey in 2021. A total of 10,794 of these participants were included in the analysis, including 1,509 COVID-19 individuals (who reported that they had tested positive for COVID-19). SRH was evaluated using a 0-100 linear visual analog scale. Habitual sleep durations of < 6 h and > 9 h were defined as short and long habitual sleep duration, respectively. Changes in habitual sleep duration after infection of ≤ -2 h and ≥ 1 h were defined as decreased or increased, respectively. RESULTS: Participants with COVID-19 had lower SRH scores than non-infected participants, and those with more severe COVID-19 had a tendency towards even lower SRH scores. In a multivariate regression analysis of participants who had experienced COVID-19, both decreased and increased habitual sleep duration after infection were significantly associated with lower SRH after controlling for sleep quality (ß = -0.056 and -0.058, respectively, both p < 0.05); however, associations between current short or long habitual sleep duration and SRH were negligible. Multinomial logistic regression analysis showed that decreased habitual sleep duration was significantly related to increased fatigue (odds ratio [OR] = 1.824, p < 0.01), shortness of breath (OR = 1.725, p < 0.05), diarrhea/nausea/vomiting (OR = 2.636, p < 0.01), and hallucinations (OR = 5.091, p < 0.05), while increased habitual sleep duration was significantly related to increased fatigue (OR = 1.900, p < 0.01). CONCLUSIONS: Changes in habitual sleep duration following SARS-CoV-2 infection were associated with lower SRH. Decreased or increased habitual sleep duration might have a bidirectional relation with post-COVID-19 symptoms. Further research is needed to better understand the mechanisms underlying these relationships for in order to improve SRH in individuals with COVID-19.

Impact of Social Support on Suicidal Ideation and Attempts Among Gender Minority Adults.

This study examined the impact of social support from family, non-gender minority friends, gender minority friends, and religious groups on suicidal ideation, suicide attempt history, and the number of suicide attempts. Researchers hypothesized that these types of social support were associated with lower suicidal thoughts and behaviors. This research is a secondary analysis of the Virginia Transgender Health Initiative Survey (THIS) data set (N = 350). Logistic regressions assessed suicidal ideation and attempts. Linear regression assessed the number of suicide attempts. Age was a covariate in all analyses. Social support from family (B = -.419, SE = .119, p < .001) was negatively associated with suicidal ideation and was not associated with an attempt history or number of attempts. This finding suggests that increasing social support from family may be an important factor to consider for suicide prevention for gender minority individuals.

Age Moderates the Relation between Sleep Problems and Suicide Risk.

OBJECTIVES: This cross-sectional study examined whether age moderates the relation between sleep problems and suicide risk and investigated whether sleep problems are differentially associated with suicide risk in younger (18-40) and older (60+) adults. METHODS: MTurk workers (N = 733) completed the Pittsburgh Sleep Quality Index, Suicidal Behavior Questionnaire-Revised, Patient Health Questionnaire, and demographic questions. Analysis of variance and linear regressions were utilized. RESULTS: Older adults scored lower on four PSQI components, symptoms of depression, and suicide risk than younger adults. Age significantly moderated the relation between sleep problems and suicide risk after controlling for gender and depressive symptoms, F(5, 635) = 72.38, p < .001. Sleep problems significantly related to suicide risk in younger adults (t = 6.47, p < .001) but not in older adults (t = 0.57, p = .57). Sleep medication use was related to suicide risk in both groups, whereas daytime dysfunction was related to suicide risk in older adults and sleep disturbances were related to suicide risk in younger adults. CONCLUSIONS: The relation between sleep problems and suicide risk differs between younger and older adults. This study adds to the literature suggesting that sleep medications may not be appropriate for older adults. CLINICAL IMPLICATIONS: Sleep problems are significantly related to suicide risk in younger adults but not older adults. Sleep medication use is associated with suicide risk regardless of age.

The association between high risk of sleep apnea, comorbidities, and risk of COVID-19: a population-based international harmonized study.

PURPOSE: Obstructive sleep apnea (OSA) may increase the risk of severe COVID-19; however, the level of potential modulation has not yet been established. The objective of the study was to determine the association between high risk of OSA, comorbidities, and increased risk for COVID-19, hospitalization, and intensive care unit (ICU) treatment. METHODS: We conducted a cross-sectional population-based web survey in adults in 14 countries/regions. The survey included sociodemographic variables and comorbidities. Participants were asked questions about COVID-19, hospitalization, and ICU treatment. Standardized questionnaire (STOP questionnaire for high risk of OSA) was included. Multivariable logistic regression was conducted adjusting for various factors. RESULTS: Out of 26,539 respondents, 20,598 (35.4% male) completed the survey. Mean age and BMI of participants were 41.5 ± 16.0 years and 24.0 ± 5.0 kg/m2, respectively. The prevalence of physician-diagnosed OSA was 4.1% and high risk of OSA was 9.5%. We found that high risk of OSA (adjusted odds ratio (aOR) 1.72, 95% confidence interval (CI): 1.20, 2.47) and diabetes (aOR 2.07, 95% CI: 1.23, 3.48) were associated with reporting of a COVID-19 diagnosis. High risk for OSA (aOR 2.11, 95% CI: 1.10-4.01), being male (aOR: 2.82, 95% CI: 1.55-5.12), having diabetes (aOR: 3.93, 95% CI: 1.70-9.12), and having depression (aOR: 2.33, 95% CI: 1.15-4.77) were associated with increased risk of hospitalization or ICU treatment. CONCLUSIONS: Participants at high risk of OSA had increased odds of having COVID-19 and were two times more likely to be hospitalized or treated in ICU.

The Association Between Sleep and Late Life Hoarding.

Sleep problems are associated with many different forms of psychopathology in late life; however, there is currently a gap in the literature on the association between sleep quality and hoarding in older adults. This secondary data analysis of 40 older adults with hoarding disorder examined the association between sleep and hoarding, change in sleep disturbance following treatment, and the impact of sleep on treatment response. Sleep disturbance was correlated with hoarding severity, and this association remained significant when controlling for inability to sleep in a bed due to clutter in a multiple regression analysis. Following treatment, there was no change in sleep disturbance using a paired t-test, and baseline sleep disturbance was not correlated with change in hoarding severity. Future studies on the potential impact of sleep disturbance on hoarding treatment in older adults should examine if targeting sleep issues adjunctively could lead to improved sleep and improved treatment adherence/efficacy.

The Relation Between Pet Ownership, Anxiety, and Depressive Symptoms in Late Life: Propensity Score Matched Analyses.

The purpose of this study was to explore the differences in anxiety and depressive symptoms between older adult pet owners and non-pet owners after accounting for various correlates. Research findings on the anxiety-relieving and antidepressant effects of late-life pet ownership are mixed and limited. This may be due in part to various characteristics that impact the likelihood of owning a pet. Propensity score matching was used to pair 169 pet owners with 169 non-pet owners aged 70 to 91 years who participated in the University of Alabama at Birmingham Study of Aging. One set of propensity scores was created using age, sex, race, rurality, marital status, and income, as well as self-reported health, difficulty with activities of daily living, and difficulty with instrumental activities of daily living. A second set of scores was created using age, sex, race, rurality, marital status, and income. Multiple linear regression analyses were then used to explore the relation between pet ownership status and anxiety or depressive symptoms, controlling for the other symptoms. Pet ownership was significantly associated with lower self-reported anxiety symptoms (ß = -0.14) but not depressive symptoms (ß = -0.03) in the data matched without health variables. When propensity score matching included health variables, pet ownership was related to neither symptoms of anxiety (ß = -0.08) nor depression (ß = 0.05). These results suggest that owning a pet in later life is related to fewer anxiety symptoms, over and above the impact of depressive symptoms, even after accounting for various demographic and economic covariates. However, general and functional health appear to be critical to this relation, but the direction of this relation could not be determined from our analyses (i.e., it is not clear whether the relation between pet ownership and anxiety symptoms is confounded by, mediates, or is mediated by health). This study is the first large-scale analysis to find a significant relation between pet ownership and fewer anxiety symptoms in older adults.

The Society of Behavioral Sleep Medicine (SBSM) COVID-19 Task Force: Objectives and Summary Recommendations for Managing Sleep during a Pandemic.

OBJECTIVE/BACKGROUND: As a response to clinical observations that the pervasive stress and social/environmental disruptions from the 2020 COVID-19 pandemic have also impacted sleep, the Society of Behavioral Sleep Medicine (SBSM) convened the COVID-19 Task Force with goals to identify and disseminate information that could be useful in addressing sleep concerns during this crisis. Participants Members of the SBSM COVID-19 Task Force. Results/Conclusions Herein is a summary of the resources developed by the SBSM COVID-19 Task force, which includes links to online materials developed for use by providers and patients, as well as brief descriptions of key recommendations by the Task Force for specific sleep conditions (e.g., acute insomnia, nightmares) and vulnerable populations (e.g., parents, essential/healthcare workers, older adults).

Examining the Contributions of Disability to Suicidality in the Context of Depression Symptoms and Other Sociodemographic Factors.

We examined the contribution of disability status to suicidality when accounting for depression and sociodemographic risk factors in 438 American adults, 82 (18.7%) of whom identified as having disabilities. Participants with disabilities had significantly higher depression scores and were more likely to be unemployed and unpartnered, all of which were also associated with increased suicidality. However, disability remained a significant predictor of suicidality even when depression and sociodemographic risk factors were accounted for in a linear regression. Other significant predictors of suicidality in this regression were female gender, depression symptoms, and family and friend suicide history; identifying as a member of a religion was a significant protective factor against suicidality. Our findings suggest that the contribution of disability to suicidality goes beyond that which can be explained by increased depression symptoms and sociodemographic vulnerability.

"It's Awful When We Get It Wrong": An Exploratory Qualitative Study of Vocational Rehabilitation Counselors' Perspectives on Suicide.

Despite the high prevalence of suicide among people with disabilities, little research has explored suicide in the context of the vocational rehabilitation (VR) system. We analyzed the responses of 27 VR counselors who responded to an open-ended qualitative prompt regarding their experiences with suicide training and competency. Key themes included a desire for more training on suicide and the experience of seeking and receiving suicide training and experience outside of VR. Responses also underscored the heavy emotional impact of working with suicidal clients, especially when one feels unprepared to do so. These results suggest that it is important to provide VR counselors with resources and training for addressing suicide in their client populations.

"I Honestly Would Not Have Known What to Do": An Exploratory Study of Perspectives on Client Suicide Among Vocational Rehabilitation Support Staff.

Despite the high prevalence of suicide both overall and among people with disabilities in particular, little research has explored suicide in the context of the vocational rehabilitation (VR) system or in counseling support staff in general. We analyzed the responses of 14 VR support staff who responded to an open-ended qualitative prompt regarding their experiences with suicide training and competency. Key themes included a perceived lack of and desire for more training regarding suicide, seeking and receiving suicide training outside of VR, and a perceived lack of resources for working with suicidal clients. Responses also underscored the heavy emotional impact of working with these clients, especially when one feels unprepared to do so. These results suggest that it is important to provide VR support staff with resources and training for addressing suicide in their client populations.

Aetiology and treatment of nightmare disorder: State of the art and future perspectives.

This consensus paper provides an overview of the state of the art in research on the aetiology and treatment of nightmare disorder and outlines further perspectives on these issues. It presents a definition of nightmares and nightmare disorder followed by epidemiological findings, and then explains existing models of nightmare aetiology in traumatized and non-traumatized individuals. Chronic nightmares develop through the interaction of elevated hyperarousal and impaired fear extinction. This interplay is assumed to be facilitated by trait affect distress elicited by traumatic experiences, early childhood adversity and trait susceptibility, as well as by elevated thought suppression and potentially sleep-disordered breathing. Accordingly, different treatment options for nightmares focus on their meaning, on the chronic repetition of the nightmare or on maladaptive beliefs. Clinically, knowledge of healthcare providers about nightmare disorder and the delivery of evidence-based interventions in the healthcare system is discussed. Based on these findings, we highlight some future perspectives and potential further developments of nightmare treatments and research into nightmare aetiology.

Treatment of Nightmares in Psychiatric Inpatients With Imagery Rehearsal Therapy: An Open Trial and Case Series.

Objectives: This study sought to assess the utility of Imagery Rehearsal Therapy (IRT) for nightmares in an inpatient psychiatric setting. Although IRT enjoys a substantial evidence base for efficacy in various populations, data with psychiatric inpatients are lacking. Participants: Participants were 20 adult psychiatric inpatients (11 male, 9 female; mean age=43.4), in an extended stay psychiatric inpatient facility. All participants were diagnosed with multiple, treatment resistant, comorbid conditions, including mood disorders, anxiety disorders, personality disorders, and substance-related disorders. Patients with active psychosis or significant cognitive impairment were excluded. Methods: This was an open trial utilizing a case series design. In addition to routine hospital treatment that included psychotherapeutic and pharmacological interventions, participants received IRT over a span of 3 weeks in 4 small group sessions. Included were education about sleep and nightmares, instruction in writing new dream narratives and practicing guided imagery, and support via further consultation and trouble-shooting. Patients were referred by their psychiatrist or were self-referred, with approval from their treatment teams. Results: Results showed significant aggregate reductions in nightmare frequency and intensity, as well as improvement in sleep overall. Patients also improved on a variety of other symptom measures, including suicidal ideation. No adverse reactions were observed. The present report includes a sampling of individual case vignettes to illustrate variability in treatment response. Conclusions: This study provides preliminary evidence that IRT can be used safely and effectively in a hospital environment to benefit patients suffering from serious mental illnesses, often in the midst of significant life crises. It is not possible in this preliminary study to conclude that IRT specifically (as opposed to other aspects of hospital treatment) produced these outcomes. Larger, controlled trials are needed to establish a causal connection between IRT and nightmare reduction.

Combined behavioural markers of cognitive biases are associated with anhedonia.

Biases towards negative information, as well as away from positive information, are associated with psychopathology. Examining biases in multiple processes has been theorised to be more predictive than examining bias in any process alone. Anhedonia is a core symptom of psychopathology and predictive of future psychopathological symptoms. Finding that combined biases are associated with anhedonia would advance knowledge of the nature of emotional processing biases and the value of objective performance-based measures for identifying early risk markers. Participants (N = 139) completed tasks that assess latency bias (dot probe) and biased recognition (two-alternative forced-choice) of emotional information, as well as an anhedonia measure. An index was computed for each task's performance reflecting biased processing of positive and negative words. Only combined biases on both tasks were associated with anhedonia. Attentional bias was positively associated with anhedonia, but only when recognition bias for emotional words was high. Thus, assessing biases in multiple domains increased sensitivity to uncover relationships between emotional processing biases and anhedonic symptoms.

Sleep Disturbance, Activities of Daily Living, and Depressive Symptoms among Older Adults.

OBJECTIVE: Research suggests sleep disturbance plays a role in depression and risk for suicidal behavior (i.e., ideation, attempts, death by suicide). How sleep disturbance affects suicide risk is unclear and one's ability to perform activities of daily living (ADLs) may help explain this relation. This study examined associations between sleep problems, ADLs, and either depressive symptoms or suicide risk among older adults. We hypothesized that ADLs would mediate relations between sleep problems and depressive symptoms and suicide risk. METHOD: Participants (N = 134; age ≥65) were recruited through Amazon's Mechanical Turk. Participants completed questionnaires that assessed insomnia symptoms, nightmares, ADLs, depressive symptoms, and suicidal behaviors. RESULTS: Nightmares were associated with depressive symptoms and suicide risk but not independently associated with ADLs. Insomnia symptoms were associated with depressive symptoms, suicide risk, and ADLs. ADLs mediated the relation between insomnia symptoms and depressive symptoms. The insomnia symptom-suicidal behavior relation and the nightmare-suicidal behavior relation were significantly mediated by a pathway containing ADLs and depressive symptoms. DISCUSSION: ADLs help explain how insomnia symptoms and nightmares confer suicide risk among older adults, either independently or in association with depressive symptoms. CLINICAL IMPLICATIONS: Practitioners should attend to ADL performance when treating older adults with insomnia and depression.

Total sleep time as a predictor of suicidal behaviour.

Insomnia symptoms are a known predictor of suicide; however, less is known about the relationship between hypersomnia and suicide, and how total sleep time may better account for suicidal ideation compared with subjective reports of insomnia symptoms. In the present secondary data analysis, a squared term confirmed the importance of both short and long total sleep time on suicidal behaviour. Total sleep time had a significant positive direct effect on suicidal behaviour (b = 0.20, SE = 0.08, P < 0.05), significant negative direct effects on insomnia symptoms (b = -1.67, SE = 0.13, P < 0.0001) and on depressive symptoms (b = -1.76, SE = 0.29, P < 0.0001). Depression had a significant positive effect on suicidal behaviour (b = 0.17, SE = 0.01, P < 0.0001), and significantly mediated the relationship between total sleep time and suicidal behaviour, but insomnia symptoms did not. Total sleep time squared had a significant positive relationship with suicidal behaviour (b = 0.02, SE = 0.01, P < 0.05), significant negative direct effects on insomnia symptoms (b = -0.12, SE = 0.01, P < 0.0001) and on depressive symptoms (b = -0.12, SE = 0.02, P < 0.0001). Depression had a significant positive effect on suicidal behaviour (b = 0.17, SE = 0.01, P < 0.0001), and significantly mediated the relationship between total sleep time and suicidal behaviour. These results suggest the importance of assessing for total sleep time in clinical settings with regard to suicide risk.