Home > Encyclopedia of Psychology > Rapid Eye Movement (REM)

The stage of sleep most closely associated with dreaming.

First described in 1953 by Nathaniel Kleitman and Eugene Aserinsky, rapid eye movement (REM) sleep is also called active sleep because the EEG (electroencephalogram) patterns in this stage are similar to the patterns during the awake stage. The four stages of slow-wave, or non-REM, sleep are accompanied by deep breathing, a relatively slow heartbeat, and lowered blood pressure. In contrast, levels of physiological arousal during REM sleep resemble those of the waking state. In some ways, however, people are more deeply asleep during the REM stage than at other times: the major muscle groups go limp in a sort of paralysis, and people are hardest to waken during REM sleep. The contradictions between the active, "awake" features of REM sleep and its soundness have caused some...