The sleep of dysthymic patients: a comparison with normal controls

All-night electroencephalographic (EEG) sleep recordings were compared in dysthymic patients and normal controls. Patients were selected according to DSM-III and underwent 2 weeks of treatment with placebo before the sleep evaluation, which also included self-assessments of sleep quality. As compared with normals, dysthymic patients demonstrated fragmented and superficial sleep with no changes in rapid eye movement (REM) sleep. In addition to sleep continuity disturbances, dysthymics had a higher percentage of stage 1 and a reduction of slow wave sleep (SWS), mainly due to a diminished percentage of stage 4. Other differences were related to a higher incidence of some EEG events, and it is suggested that the analysis of sleep microstructure is a useful approach to study sleep physiology in psychiatric patients. The classification of minor forms of depression is a controversial issue and therefore the nosological implications of our findings are discussed.