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 Fitbits with heart rate monitors can discern between light sleep, deep sleep, and REM sleep, when vivid dreams are more likely. David Nield, WIRED, 4 May 2024 Yet one emerging theory is that the fantastical dreams experienced during REM sleep tame emotions attached to memories and help people gain a broader understanding of what happens to them. Ingrid Wickelgren, Scientific American, 20 Feb. 2024 Try integrating an Oura ring, a sleek wearable that tracks resting heart rate, REM sleep, and sleep quality, as well as real-time stress levels, giving the user tangible data to work with. Krista Simmons, Sunset Magazine, 22 Jan. 2024 Even across mammals, REM sleep doesn’t all look the same. Carolyn Wilke, Smithsonian Magazine, 13 Sep. 2023 Causes of Type 1 narcolepsy can include autoimmune disorders and brain injuries, but the underlying issue is believed to be low levels of hypocretin, a hormone that is thought to affect REM sleep — the dream state. Tribune News Service, Hartford Courant, 15 Jan. 2024 Given that alcohol is a sedative, achieving sleep right away is often shorter for drinkers, and some fall into deep sleep rather quickly, which can create an imbalance between slow-wave sleep and REM sleep, resulting in less of the latter and more of the former. Dominique Fluker, Essence, 2 Jan. 2024 Participants seemed to react more negatively to experiences after losing REM sleep in particular, suggesting that the different neural processes involved throughout the sleep cycle could affect daytime emotions in different ways. TIME, 21 Dec. 2023 One example that raises doubts is the fact that the blind mole rat does not see and still experiences REM sleep. Roberta McLain, Scientific American, 12 Dec. 2023

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'REM sleep.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

First Known Use

1963, in the meaning defined above

Time Traveler
The first known use of REM sleep was in 1963

Dictionary Entries Near REM sleep

Cite this Entry

“REM sleep.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/REM%20sleep. Accessed 20 Jun. 2024.

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
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