The beneficial effect of antidepressant interventions has been proposed to depend on suppression of rapid eye movement (REM) sleep or inhibition of electroencephalographic (EEG) slow-wave activity (SWA) in non-REM sleep. Use of the monoamine oxidase inhibitor phenelzine sulfate can eliminate REM sleep. We studied the relation between REM sleep suppression and antidepressant response and the effect of phenelzine therapy on sleep EEG power spectra.
Open-labeled prescriptions of 30 to 90 mg of phenelzine were given to 11 patients with major depressive disorder (6 men and 5 women; mean age, 41.4 years); all were physically healthy. Mood, dream recall, sleep, sleep EEG, and ocular and muscular activity during sleep were studied before treatment and during the third and fifth weeks of pharmacotherapy.
Six patients remitted from depression, 2 responded partially, and 3 showed no antidepressant response. Independent from clinical response, REM sleep was dramatically suppressed. On average, only 4.9 minutes of REM sleep was observed in treatment week 5, and it was completely absent in 6 patients. This effect was compensated for by increased stage 2 sleep. In non-REM sleep, EEG power was higher than at baseline between 16.25 and 25 Hz. Slow-wave activity (power within 0.75-4.5 Hz) and the exponential decline of SWA during sleep were not affected.
Antidepressant response to phenelzine treatment does not depend on elimination of REM sleep or inhibition of SWA in non-REM sleep. In depressed patients, REM sleep is regulated independently from non-REM sleep and can be manipulated without altering the dynamics of SWA.