Changes in paradoxical sleep accompanying instrumental learning in the cat

Five animals were used as their own controls for a replication on cats of earlier findings of facilitated paradoxical sleep (PS) after learning. The experiment was based on an instrumental conditioning with positive reinforcement and three-hour recordings of the subsequent sleep. Facilitation was observed as (a) an increase in the amount of PS during the first 45 min of sleep, (b) an increase in PS episode duration, (c) a decrease in PS latencies and (d) a decrease in slow wave duration versus PS episode duration in the early sleep cycles. The lengthening of PS phases was the only change closely correlated with the state of acquisition.