Effects of REM sleep deprivation on responding under multiple schedules offree-operant avoidance

The effects of REM sleep deprivation on free-operant avoidance in rats was examined. Six rats were taught to press a lever to postpone shock for a fix ed period of time after each response (response-shock [RS] interval). If th ey failed to press the lever; shocks were delivered after a fixed period of time (shock-shock [SS] interval). The subjects were exposed to a multiple schedule of reinforcement in which RS intervals were varied, but SS interva ls were held constant. For each animal, baselines were established in which the length of the RS interval was inversely related to response rate. The subjects were then repeatedly exposed to 24, 48, or 96 h of REM sleep depri vation under identical tank control and cage control conditions. Compared w ith baseline and control conditions, REM sleep deprivation increased respon se rates. Increases in response rates were primarily accounted for by incre ases in brief interresponse times. The percentage of avoided shocks was not significantly altered across conditions.