Insomnia, sleep duration and incidence of depressive and anxiety disorders results from a large cohort study

background Sleep disturbances are thought to increase the risk of developing depressive and anxiety disorders. However, evidence up until now is not conclusive. objective To determine associations between insomnia and sleep duration at baseline and the incidence of depressive and anxiety disorder during two year follow-up in a sample free of lifetime depressive and anxiety disorders at baseline, while adjusting for the effect of subclinical depressive symptoms, sociodemographics and somatic health indicators. Methods Data are from the Netherlands Study of Depressive and Anxiety Disorders, a longitudinal cohort study. Subjects without lifetime depressive and anxiety disorders at baseline (n=565) were selected for the current study. Incidence of depressive and anxiety disorders over two years of follow-up according to the Composite International Diagnostic Interview based on DSM-IV criteria. Results Insomnia and short sleep duration at baseline were significantly associated with 2-year incidence of depressive and anxiety disorders (OR Insomnia=4.23, 95% CI=2.15-8.33, OR short sleep duration=2.70, 95% CI= 1.35-5.48). Associations remained present after considering baseline subclinical depressive symptoms, sociodemographics and somatic health indicators. limitations Sleep measures were based on self-report only. Conclusions Both insomnia and short sleep duration are independent risk factors for incident depressive and anxiety disorders. Future research is needed to determine if interventions directed at improving sleep are effective in preventing these disorders. Chapter 4