non-REM sleep

noun

ˈnän-ˌrem- 

variants or NREM sleep

ˈen-ˌrem- 

: a state of sleep that occurs regularly during a normal period of sleep with intervening periods of REM sleep and is characterized by delta wave brain activity, little dreaming, and a reduced level of autonomic physiological activity

Non-REM sleep is a quiet sleep state. The muscles are relaxed but maintain some tone, breathing is regular, the cerebral cortex generates high-voltage waves, and consumption of energy by the brain is minimal.

—Jerome M. Siegel

For most people the few dreams found in non-REM sleep tend to have a rather thought-like character. During REM sleep, on the other hand, dreams occur more frequently and usually have a perceptual vividness …

—Francis Crick et al.

NREM sleep … is crucial to memory retention, and to acquiring and refining our motor skills.

—David Kamp

compare rem sleep, slow-wave sleep

Examples of non-REM sleep in a Sentence

Recent Examples on the Web

Sleep research has shown that parasomnias often arise during the transitions to and from non-REM sleep. —Steve Nadis, Discover Magazine, 26 Nov. 2023

Marsupial mammals called echidnas show characteristics of REM and non-REM sleep at the same time. —Carolyn Wilke, Smithsonian Magazine, 13 Sep. 2023

The researchers also departed from the traditional approach of examining brain waves in segregated sleep stages—like rapid eye movement (REM) and non-REM sleep—and instead analyzed wave patterns as part of a full continuum of gradual changes that occur during sleep. —Lucy Tu, Smithsonian Magazine, 24 Mar. 2023

Word History

First Known Use

1963, in the meaning defined above

Medical Definition

non-REM sleep

noun

-ˌrem- 

variants or NREM sleep

ˈen-ˌrem- 

: a state of sleep that occurs regularly during a normal period of sleep with intervening periods of REM sleep and is characterized by delta wave brain activity, little dreaming, and a reduced level of autonomic physiological activity

Non-REM sleep is a quiet sleep state. The muscles are relaxed but maintain some tone, breathing is regular, the cerebral cortex generates high-voltage waves, and consumption of energy by the brain is minimal.

—Jerome M. Siegel

NREM sleep … is crucial to memory retention, and to acquiring and refining our motor skills.

—David Kamp

called also orthodox sleep, S sleep, synchronized sleep

compare rem sleep, slow-wave sleep