Sleep EEG recordings in depressive disorders.

Sleep polygraphic recordings were performed during 3 consecutive nights in a sample of 43 affectively ill inpatients. The patients were classified as major (n = 36) or minor depressive disorder (n = 7), according to the Research Diagnostic Criteria. Among the 36 patients with a major depressive disorder, 14 were in remission at the time of the sleep investigation. A two-way analysis of variance was performed to assess night and diagnostic effect on sleep variables. Shortening of REM latency was observed in depressed patients with major depressive disorder when compared to major depressive disorder patients in remission. Depressed patients with major depressive disorder also showed higher REM activity and REM density values than patients with minor depressive disorder. According to the linear discriminant analysis, sleep variables were able to correctly classify 68% of the patients.