REM sleep deprivation and food competition in male rats

Effects of partial food restriction on nocturnal meal size and feeding speed are counteracted by concurrent REM sleep deprivation in the rat

Effects of rapid eye movement (REM) sleep deprivation on meal size and feeding speed were investigated by means of the cuff pedestal technique in 9 male rats exposed to partial food restriction. Reduction of available food by 50% alone, when accomplished by providing the pellets at the beginning of each dark period, during 7 consecutive days, induced a quite linear increase both in the meal size and feeding speed. When the same feeding schedule was repeated in combination with REM sleep deprivation, the meal size remained smaller and the feeding time was prolonged (during the first 3-4 days) when compared to those during food restriction alone, although losses of body weight were almost doubled. These findings are in agreement with the effects of REM sleep deprivation on the meal pattern in rats on ad libitum diet and provide further support for the suggestion of the importance of REM sleep in the generation of the light/dark rhythm of feeding in the rat.

Swimming immobility of REM sleep deprived rats reared in different environments

This study tested the hypothesis that environmental rearing treatments which alter the REM sleep levels of rats affect swimming immobility, an adaptive, REM sleep sensitive behavior. At weaning, 72 female Sprague-Dawley rats were maintained in either an enriched, an impoverished, or a social control environment for 32-33 days. They were then placed in either a REM sleep depriving platform-in-water condition or in one of two control conditions (large platform or dry control) for 4 days before being scored for swimming immobility during a 10-min swimming test. A 3 (environments) X 3 (platforms) ANOVA revealed a main effect for environments, F(2,63) = 5.20, p less than 0.01. Enriched rats exhibited a behavioral advantage over impoverished rats under the large platform control condition, F(1,63) = 6.58, p less than 0.025, and under the dry control condition, F(1,63) = 6.14, p less than 0.025. However, under the REM depriving condition, their behavioral advantage was virtually eliminated, F(1,63), p less than 1. The conclusion that the REM sleep levels of the rat groups probably determined their swimming immobility scores is discussed.