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 birth (E) were polygraphically recorded in 3 3-hr 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.