Nocturnal sleep disturbances as a predictor of suicide attempts among psychiatric outpatients: a clinical, epidemiologic, prospective study

Abstract

Objective: Nocturnal sleep disturbances, including insomnia and recurrent nightmares, represent common distressing sleep complaints that might have important prognostic and therapeutic implications in psychiatric patients. The present study aimed at investigating nocturnal sleep disturbances in relation to the risk of suicide attempts in a consecutive cohort of psychiatric outpatients.

Method: Participants attending a psychiatric outpatient clinic in Hong Kong were recruited into the study with a detailed sleep questionnaire assessment. The questionnaire was distributed between May and June 2006. Relevant clinical information, with a comprehensive clinical history of patients since their attendance at psychiatric services and 1 year after completion of their questionnaires, was reviewed.

Results: The final study population consisted of 1,231 psychiatric outpatients with a mean age of 42.5 years (SD = 11.3; range, 18-65). Both frequent insomnia and recurrent nightmares were significantly and independently associated with an increased incidence of suicide attempts 1 year after questionnaire assessment (insomnia: OR = 6.96; 95% CI, 1.21-39.97; recurrent nightmares: OR = 8.17; 95% CI, 1.06-63.13) and an increase in lifetime prevalence of suicide attempts (insomnia: OR = 1.55; 95% CI, 1.06-2.25; recurrent nightmares: OR = 2.43; 95% CI, 1.51-3.91). Comorbid insomnia and nightmares had increased odds of lifetime prevalence (OR = 2.43; 95% CI, 1.53-3.85) and 1-year incidence of suicidal risk (OR = 17.08; 95% CI, 2.64-110.40). Antidepressants, particularly selective serotonin reuptake inhibitors (OR = 1.52; 95% CI, 1.02-2.25), serotonin-norepinephrine reuptake inhibitors (OR = 2.10; 95% CI, 1.15-3.83), heterocyclics (OR = 2.78; 95% CI, 1.21-6.42), and non-benzodiazepine hypnotics (OR = 1.54; 95% CI, 1.02-2.33) were independently associated with recurrent nightmares after adjustment for confounding variables.

Conclusions: Nocturnal sleep disturbances, particularly frequent insomnia and recurrent nightmares, were independently associated with enhanced suicidal risk among psychiatric patients. Future studies are warranted to investigate the underlying pathophysiologic mechanism and interventional responses.