Sleep after immobilization stress and sleep deprivation: common features and theoretical integration.

The goal of the present paper is to elucidate and to resolve contradictions in the relationships among different forms of stress, sleep deprivation, and paradoxical sleep (PS) functions. Acute immobilization stress and the stress of learned helplessness are accompanied by an increase of PS, whereas the stress of defense behavior and the stress of self-stimulation cause PS reduction. Recovery sleep after total sleep deprivation performed on the rotating platform is marked by a dramatic rebound of PS although NREM (non-rapid eye movement) sleep deprivation is more prominent than PS deprivation. This PS rebound leads to a quick reversal of the pathology caused by prolonged sleep deprivation. The search activity (SA) concept presents an explanation for these contradictions. SA increases body resistance to stress and diseases, whereas renunciation of search (giving up, helplessness) decreases body resistance. PS and dreams contain covert SA, which compensates for the lack of the overt SA in the preceding period of wakefulness. The requirement for PS increases after giving up and decreases after active defense behavior and self-stimulation. Immobilization stress prevents SA in waking behavior and increases the need in PS. Sleep deprivation on the rotating platform, like immobilization stress, prevents SA, produces conditions for learned helplessness and, suppresses PS. Such a combination increases PS pressure and decreases body resistance.