Sleep Disturbances and Suicide Risk in an 8-Year Longitudinal Study of Schizophrenia-Spectrum Disorders

Study Objectives: Disrupted sleep is one of the prominent but often overlooked presenting symptoms in the clinical course of psychotic disorders. The aims of this study were to examine the prevalence of sleep disturbances, particularly insomnia and nightmares, and their prospective associations with the risk of suicide attempts in patients with schizophrenia-spectrum disorders. Methods: A naturalistic longitudinal study was conducted in outpatients diagnosed with schizophrenia-spectrum disorders recruited from the psychiatric outpatient clinic of a regional university-affiliated public hospital in Hong Kong. A detailed sleep questionnaire was completed by 388 patients at baseline in May-June 2006. Relevant clinical information was extracted from clinical case notes from June 2007-October 2014. Results: Prevalence of frequent insomnia and frequent nightmares was 19% and 9%, respectively. Baseline frequent insomnia was significantly associated with an increased incidence of suicide attempts during the follow-up period (adjusted hazard ratio = 4.63, 95% confidence interval 1.40-15.36, P < 0.05). Nightmare complaint alone did not predict the occurrence of suicide attempts, but the comorbidity of nightmares and insomnia was associated with the risk of suicide attempt over follow-up (adjusted HR = 11.10, 95% confidence interval: 1.68-73.43, P < 0.05). Conclusions: Sleep disturbances are common in patients with schizophrenia-spectrum disorders. The association between sleep disturbances and suicidal risk underscores the need for enhanced clinical attention and intervention on sleep disturbances in patients with schizophrenia.