We studied the effects of 48 h of REM sleep deprivation on spontaneous and post-sigh central apneas in Sprague-Dawley rates by simultaneously monitoring sleep by the EEG and respiration for 6 h. During the recovery sleep following REM deprivation a decrease in post-sigh apneas occurred in total sleep. There was no change in spontaneous apneas. The results suggest the existence of partially distinct mechanisms for the two types of apneas.