[Chronobiology of depression].

Depressive signs and symptoms can change on a daily, monthly and annual scale (diurnal variation of mood, premenstrual dysphoric disorder, seasonal affective disorders). This can be understood as a coupling of psychopathology to pre-existing rhythmic processes (association hypothesis). Also early morning awakening, short REM-sleep-latencies and the antidepressive effects of sleep deprivation and of phase advance therapy bear no evidence of a particular chronopathology in depression. Correspondingly, most studies in depressives have not shown an abnormal phasing of circadian rhythms.