Relationship of Rapid Eye Movement Density to the Prior Accumulation of Sleep and Wakefulness

Ocular activity during the REM stage of sleep was studied for the purpose of determining what effect previous sleep and waking would have on the intensity of that activity. Eleven S s slept to satiation during a 54‐hr session and then, after a day of waking, slept for another night. REM density (i.e., number of eye mvts per min of REM period) rose progressively during the first night and morning, and then remained at a high level for the remainder of the 54 hrs; the mean REM density for Night 2 and also for Night 3 was about double the REM density of Night 1. Multiple regression analysis indicated that the amount of prior sleep was positively correlated with REM density whereas the amount of waking was negatively correlated. Peak REM density occurred after a mean of 9.88 hrs of sleep. Thereafter, periods of waking alternated with periods of sleep while the REM density oscillated at its peak level. It was concluded that REM density reflects the output of a sleep‐waking negative feedback circuit.