Sleep deprivation and phasic activity of REM sleep: Independence of middle-ear muscle activity from rapid eye movements

In the recovery nights after total and partial sleep deprivation there is a reduction of rapid eye movements during REM sleep as compared to baseline nights; recent evidence provided by a selective SWS deprivation study also shows that the highest percentage of variance of this reduction is explaine d by SWS rebound. The present study assesses whether the reduction of rapid eye movements (REMs) during the recovery night after total sleep deprivati on is paralleled by a decrease of middle-ear muscle activity (MEMA), anothe r phasic muscle activity of REM sleep. Standard polysomnography, MEMA and REMs of nine subjects were recorded for three nights (one adaptation, one baseline, one recovery); baseline and rec overy night were separated by a period of 40 hours of continuous wake. Results show that, in the recovery night, sleep deprivation was effective i n determining an increase of SWS amount and of the sleep efficiency index, and a decrease of stage 1, stage 2, intra-sleep wake, and NREM latencies, w ithout affecting REM duration and latency. However, MEMA frequency during R EM sleep did not diminish during these nights as compared to baseline ones, while there was a clear effect of REM frequency reduction. Results indicate an independence of phasic events of REM sleep, suggesting that the inverse relation between recovery sleep after sleep deprivation an d REM frequency is not paralleled by a concomitant variation in MEMA freque ncy.