Sleep deprivation in the rat: IX. Recovery.

Eight rats were subjected to total sleep deprivation, paradoxical sleep deprivation, or high amplitude sleep deprivation until they showed major deprivation-induced changes. Then they were allowed to sleep ad lib. Three rats that had shown the largest temperature declines died within two to six recovery days. During the first 15 days of ad lib sleep, surviving rats showed complete or almost complete reversal of the following deprivation-induced changes: debilitated appearance, lesions on the paws and tail, high energy expenditure, large decreases in peritoneal temperature, high plasma epinephrine and norepinephrine levels, and low thyroxine levels. The most prominent features of recovery sleep in all rats were immediate and large rebounds of paradoxical sleep to far above baseline levels, followed by lesser temporally extended rebounds. Rebounds of high amplitude non-rapid eye movement (NREM) sleep occurred only in some rats and were smaller and less immediate.