Acute changes in sleep-related hormone secretion of depressed patients following oral imipramine.

Tricyclic antidepressants have acute effects on hormone secretion when given either orally or parenterally in the morning. These drugs also have acute effects on the sleep electroencephalogram (EEG) when given immediately before sleep onset. In particular, imipramine significantly delays the REM-nREM cycle and increases the amount of delta wave activity. This study shows that an oral dose of 50 mg imipramine given at bedtime to depressed patients has little effect on the secretion of prolactin and melatonin, but acutely advances the secretion of growth hormone and cortisol. This suggests that sleep and hormone secretion may only be temporally related, as they can be dissociated pharmacologically.