Background: Sleep problems may lead to, or be symptomatic of, depression and other mental illnesses yet few studies have investigated their association with suicide risk.
Design: Prospective cohort study.
Setting: Taiwan.
Participants: 393,983 men and women aged 20 or above participating in the MJ health check-up programme.
Results: There were 335 suicides over a mean of 7.4 years follow-up. There was a reverse J-shaped association between sleep duration and suicide risk. When compared with those sleeping 6-8 h per night the adjusted hazard ratios (95% confidence intervals) for suicide associated with 0-4, 4-6 and >8 h sleep were 3.5 (2.0-6.1), 1.5 (1.1-1.9) and 1.5 (1.1-2.0), respectively. People requiring sleeping pills to get to sleep (1.2% participants) were at over 11-fold increased risk; difficulty falling asleep (11.5% participants), frequent dreaming (16.7%) and being easily awoken (30.6%) were associated with a 2.0-, 1.6- and 1.3-fold increased risk of suicide, respectively.
Conclusions: Less than 6 h sleep duration, sleep disturbances and reported use of sleep medicines are markers of suicide risk. Sleep problems should be assessed when evaluating suicide risk.