Association between hospital-diagnosed sleep disorders and suicide: A nationwide cohort study.

STUDY OBJECTIVES: Sleep disorders are related to mental disorders. Yet few studies have examined their association with suicide. We examined whether males and females diagnosed with sleep disorders had higher rates of suicide than individuals not diagnosed with sleep disorders. METHODS: In a cohort study, nationwide data on all males and females aged 15+ years living in Denmark during 1980-2016 were analysed. Sleep disorders were identified through diagnoses recorded during contacts to somatic hospitals. Incidence Rate Ratios (IRR) were estimated using Poisson regression models and adjusted for covariates. RESULTS: In all, 3,674,563 males and 3,688,164 females were included, of whom 82,223 (2.2%, mean age: 50.2, SD: 17.5) males and 40,003 (1.1%, mean age: 50.6, SD: 19.9) females had sleep disorder diagnoses. Compared to those with no sleep disorders, the adjusted IRRs for suicide were 1.6 (95% CI, 1.4-1.7) and 2.2 (95% CI, 1.8-2.6) for males and females with sleep disorders, respectively. Excess rates for narcolepsy were found for males (IRR:1.2, 95% CI, 1.0-1.5) and females (IRR:3.3, 95% CI, 3.0-4.1), and for sleep apnea in males (IRR:1.8, 95% CI, 1.5-2.2). A difference with respect to age and sex was observed (P<0.001) between males and females. Males and females had IRRs of 4.1 (95% CI, 3.1-5.5) and 7.0 (95% CI, 4.8-10.1), during the first 6 months after being diagnosed with a sleep disorder. CONCLUSIONS: Sleep disorders were associated with higher suicide rates even after adjusting for pre-existing mental disorders. Our findings suggest attention towards suicidality in patients with sleep disorders is warranted.