As part of the National Institute of Mental Health Epidemiologic Catchment Area study, 7954 respondents were questioned at baseline and 1 year later about sleep complaints and psychiatric symptoms using the Diagnostic Interview Schedule. Of this community sample, 10.2% and 3.2% noted insomnia and hypersomnia, respectively, at the first interview. Forty percent of those with insomnia and 46.5% of those with hypersomnia had a psychiatric disorder compared with 16.4% of those with no sleep complaints. The risk of developing new major depression was much higher in those who had insomnia at both interviews compared with those without insomnia (odds ratio, 39.8; 95% confidence interval, 19.8 to 80.0). The risk of developing new major depression was much less for those who had insomnia that had resolved by the second visit (odds ratio, 1.6; 95% confidence interval, 0.5 to 5.3). Further research is needed to determine if early recognition and treatment of sleep disturbances can prevent future psychiatric disorders.