REM Rebound

REM rebound is the phenomenon in which rapid eye movement, or REM, sleep becomes both longer in duration and more frequent following a period during which a person has been deprived of adequate REM sleep. The underlying mechanism is described as a buildup of physiological pressure to obtain REM sleep during the period of deprivation, which is then discharged once the person is able to sleep without further interruption, producing REM periods that make up a substantially higher percentage of total sleep than usual. People who have been selectively deprived of REM sleep also show reduced REM latency, meaning they reach the REM stage more quickly than usual after falling asleep. In one documented study, participants deprived of dream sleep for five nights showed their REM percentage rise from an average of 19.4 percent of total sleep to an average of 26.6 percent once allowed to sleep undisturbed. REM rebound is treated as evidence that REM sleep serves an essential biological function beyond general rest, since the brain appears to actively compensate for a REM deficit, and the phenomenon can occur naturally after sleep deprivation or as a side effect of stopping certain medications, including some antidepressants, that suppress REM sleep during their use.