REM sleep

noun

: a state of sleep that recurs cyclically with non-REM sleep several times during a normal period of sleep, is characterized especially by greatly depressed muscle tone, dreaming with vivid imagery, rapid eye movements, and increased neuronal activity in certain brain regions (such as the pons), and typically comprises up to 25% of time spent in sleep

REM sleep, it soon became apparent, occurs in intervals throughout the night, usually four to six times, each lasting from ten minutes to an hour.

—Martin Gardner

People awakened during REM sleep usually report dreams with visual images and storylike narratives.

—Lis Harris

called also paradoxical sleep, rapid eye movement sleep

compare slow-wave sleep, non-REM sleep

Examples of REM sleep in a Sentence

Recent Examples on the Web

Nightmares, on the other hand, are concentrated in the second half of the night during REM sleep. —Lori Miller Kase, Parents, 30 Oct. 2024

Regularly occurring bouts of retinal movements suggest an REM sleep–like state in jumping spiders Washington State University. —Jake Parks, Discover Magazine, 14 Oct. 2024

Fish, however, do not have a neocortex in their brains so the propagating wave sleep is not the same as REM sleep. —Discover Magazine, 1 Oct. 2024

Follows newlyweds Hyun-su (the late Parasite start Lee Sun-kyun) and Soo-jin (Jung Yu-mi), whose domestic bliss is disrupted when Hyun-su develops a dangerous REM sleep disorder. —Jill Goldsmith, Deadline, 27 Sep. 2024

Word History

First Known Use

1963, in the meaning defined above

Medical Definition

REM sleep

noun

: a state of sleep that recurs cyclically with non-REM sleep several times during a normal period of sleep, is characterized especially by greatly depressed muscle tone, dreaming with vivid imagery, rapid eye movements, and increased neuronal activity in certain brain regions (as the pons), and typically comprises up to 25% of time spent in sleep

REM sleep, it soon became apparent, occurs in intervals throughout the night, usually four to six times, each lasting from ten minutes to an hour.

—Martin Gardner

People awakened during REM sleep usually report dreams with visual images and storylike narratives.

—Lis Harris

called also desynchronized sleep, paradoxical sleep, rapid eye movement sleep

compare non-rem sleep