Afternoon fatigue and somnolence associated with tranylcypromine treatment.

The author examined a series of 23 depressed and 15 obsessive compulsive disorder outpatients who were treated with 40-80 mg/day of tranylcypromine to determine the frequency and clinical features of fatigue and somnolence. Four (all depressed) of the 38 patients experienced hypersomnolence and fatigue in the late afternoon. The somnolence was severe enough to impair their ability to work and drive. Afternoon fatigue and somnolence appear to be important and not uncommon side effects of tranylcypromine treatment.