The two stages of slow wave sleep in the cat and their relation to REM sleep

Abstract

The sleep-wakefulness cycling has been recorded for two 24 h periods in each of 12 adult cats. Polygraphic recordings included EEG, neck EMG and eye movements. Four stages were identified: awake (including drowsiness), REM sleep, and two stages of slow wave sleep, labeled light and deep slow wave sleep. The two stages of slow wave sleep differ in regard to polygraphic characteristics, and they also differ in their relation to REM sleep. Cats with large amounts of deep slow wave sleep also had large amounts of REM sleep (positive correlation, P < 0.02). Amounts of light slow wave sleep were negatively correlated to amounts of deep slow wave sleep (P < 0.02). A tendency towards negative correlation between light slow wave sleep and REM sleep did not reach significance. Such a relation between deep slow wave sleep and REM sleep has not been described previously in any species. © 1968.