[Fatigue and depression (author's transl)].

Fatigue is usually stated as a major symptom of the depressive condition. Its diagnosis value seems higher in mild depressions, that in severe depressive syndromes. In this later case the symptom is overwhelmed by psychic pain. Contrary to the common viewpoint fatigue does not seem a consequence of sadness and lack of interest. It seems we have to make a distinction between the fatigue related to anxiety and hypochondria and an other kind of fatigue that is the subjective aspect of motor and mental retardation. Its relationships with circadian rhythms and nor-adrenergic transmission are probably the best ways to explore the biological mechanisms.