Nightmares as Predictors of Suicide

STUDY OBJECTIVES: To examine the relationship between the frequency of nightmares and the risk of suicide. DESIGN AND SETTING: A prospective follow-up study in a general population of Finland starting in 1972. PARTICIPANTS: A total of 36,211 subjects (17,700 men and 18,511 women) aged 25-64 years at baseline. INTERVENTIONS: N/A. MEASUREMENTS: The study included self-administered questionnaires (mainly questions on socio-economic factors, medical history, health behavior, and psychosocial factors) and health examination at the local primary healthcare center. The frequency of nightmares was estimated. The subjects were followed until Dec. 31, 1995, or death. Information on deaths caused by suicide (n=159) or other self-inflicted injury was obtained from the National Death Register by computerized record linkage using the national personal identification code assigned to every Finnish resident. Using the Cox proportional hazards regression model we controlled for several potential confounding factors. RESULTS: The frequency of nightmares was directly related to the risk of suicide. Among subjects having nightmares occasionally the adjusted relative risk of suicide was 57% higher, and among those reporting frequent nightmares 105% higher compared with subjects reporting no nightmares at all. CONCLUSIONS: This is the first study to report a direct and graded association between the frequency of nightmares and death from suicide in a general population.