[Antidepressive effect of partial sleep deprivation during the 1st half of the night].

In addition to previous investigations another modification of sleep-deprivation (SD) was studied in 28 endogenous depressives: SD during the 1st half of the night. From the day of deprivation - in the self-rating from the 4th day - up to 1 week later a therapeutic effect can be observed. The psychic part of the symptomatology was more reduced than the somatic one. Compared to total and partial SD during the 2nd half of the night, there is, on average, a smaller therapeutic effect which occurs later. The diurnal variation of the depressive symptomatology is less influenced. According to the period without sleep, the circadian course of the heart rate is less and differently modified by SD during the 1st half of the night. Only an existing diurnal variation (before SD) is a predictor of the prompt effect. Implications for the mechanism of the therapeutic SD were discussed. For clinical practice, SD during the 2nd half of the night is the method of choice.