Diurnal variations of mood in depressed patients in relation to severity of depression.

This study investigates the relationship between the severity of the depressive syndrome and the occurrence of diurnal mood variation. Several authors have proposed that diurnal variations of mood cease in the severest states of depression. By contrast, others suggest a rhythm-inducing effect of depression. We could not find any correlation between the severity of depression and various measures of diurnal mood variation in a group of 70 patients. These findings are discussed against the background of chronobiological hypotheses.