Sleep disorders and suicidal ideation in Japanese patients visiting a psychosomatic clinic in a university hospital

The Japanese suicide rate has been increasing rapidly. This phenomenon may be potentially attributable to the increase in the incidence of several mental disorders such as depression. Sleep disorders are the most frequent physical symptoms observed in depression, and are considered to be common complaints in general medical clinics. The objective of the present study was to assess the relation between suicidal ideation and sleep disorders in the primary care setting in a psychosomatic clinic. Subjects were 231 new outpatients who visited the department of psychosomatic medicine in a university hospital. suicidal ideation, sleep disorders and other confounding factors related to their psychosocial environment were assessed by psychological tests using questionnaires, and by the patient's chief complaints. Depression and anxiety disorders were assessed using the DSM-IV diagnostic criteria. Logistic regression analysis was used to calculate the odds ratio and its 95% confidence interval with adjustment for all the relevant factors. In multivariate analysis, both insomnia and overall sleep disorders were statistically significantly or nearly significantly associated with an increased risk of suicidal ideation, even after adjusting for depression and anxiety. This trend was clearer in patients without major depressive disorder than in those with a major depressive disorder. Both insomnia and overall sleep disorders were associated with suicidal ideation independently of depression and anxiety. Clinicians working in a primary care setting should therefore be cautious when dealing with these sleep disorders which may be signs of suicide.