The influence of some monoamine oxidase inhibitors (phenelzine, transamin [tranylcypromine], nialamide) on the structure of the sleep-wakefulness cycle of the cat was studied. It was shown that these monoamine oxidase inhibitors elicit and increase in slow-wave sleep in the sleep-wakefulness cycle due to complete suppression of paradoxical sleep and significant decrease in wakefulness. After the cessation of the action of the monoamine oxidase inhibitors, a selective rebound of wakefulness is observed against the background of complete or partial absence of paradoxical sleep. The gives grounds for the hypothesis that during partial deprivation of wakefulness under the influence of monoamine oxidase inhibitors an intensification occurs on the accumulation of specific need for this physiological state, the satisfaction of which is accomplished as the result of its rebound in the post-deprivational cycle, i.e., after the termination of the EEG of the synchronizing effect of the monoamine oxidase inhibitors.