Effect of light deprivation on sleep in the rat

The sleep-wake cycles of 24- and 30-day-old rats reared in darkness from 48 hr after bith (E) were polygraphically recorded in 3 3-hour sessions (0900-1200 hr; 1230-1530 hr; 1600-1900 hr) and compared to normally reared controls (C). The total amount of paradoxical sleep (PS) over the 3 3-hr sessions of the light-deprived rats (E24 and E30) was significantly less than in the controls (C24, and C30). The distribution of PS over the 3 sessions was different for the control groups: C24 showed a significantly greater amount of PS and SWS during 1230-1530 hr, and C30 during 1230-1530 and 16-19 hr. Light-deprived groups showed no significant variations neither in PS nor in SWS or W within the three sessions. These data fail to support the hypothesis that PS functions as a compensatory stimulation under conditions of low stimulation.