Sleeping Problems and Suicide in 75,000 Norwegian Adults: A 20 Year Follow-up of the HUNT I Study

Objectives: To Investigate the association of sleeping problems with suicide risk. Design: Prospective cohort study linking health survey information on sleep problems of Norway's national mortality registry. Participants were followed up from 1984-6 until December 31, 2004. Setting: Residents of Nord-Trondelag County, Norway, aged 20 years or older in 1984-6. Participants: Altogether 87.285 people were eligible for the surveye and 74,977 (86%) took part in one or more aspects of the study. Interventions: N/A Measurements and Results: Three percent of participants experienced sleeping problems every night, 5% experienced problems "often" and 31% reported problems "sometimes." There were 188 suicides during follow-up. Sleeping problems at baseline were strongly associated with subsequent suicide risk. Compared to participants who reported no sleeping problems the age- and sex- adjusted hazard ratios for suicide were 1.9 (CI 1.3-2.6). 2.7 (CI 1.4-5.0), and 4.3 (CI 2.3-8.3) for reporting sleeping problems sometimes, often, or almost every night, respectively. Associations were stronger in younger (< 50 years) participants, but we found no statistical evidence for gender differences. Adjusting for measures of common mental disorder and alcohol use at baseline weakened the associations, but the 3% of subjects with the worst sleep patterns remained at two fold increased risk of suicide. Conclusions: Sleeping problems are a marker of suicide risk, mainly due to presence of both sleeping and mixed anxiety and depression. Physicians should be aware of the possible vulnerability for people affected by sleeping problems.