REM sleep

noun

, Physiology.

1. a recurrent period of sleep, typically totaling about two hours a night, during which most dreaming occurs as the eyes move under closed lids and the skeletal muscles are deeply relaxed. Compare slow-wave sleep.

REM sleep

/ rĕm /

1. Short for rapid eye movement sleep. A period of sleep characterized by rapid periodic twitching movements of the eye muscles and other physiological changes, such as accelerated respiration and heart rate, increased brain activity, and muscle relaxation. REM sleep is associated with activity in the pons of the brainstem; when the pons is eliminated, REM sleep does not occur. REM sleep is the stage of sleep in which most dreaming takes place and is thought to allow for the organization of memories and the retention of learning. REM sleep is the fifth and last stage of sleep that occurs in the sleep cycle, which repeats itself about five times throughout a period of sleep. It is preceded by four stages of non-REM sleep. REM stages become longer with each cycle and account for about 20–25 percent of total sleep in adult humans. In infants, roughly 50 percent of sleep is REM sleep, which is believed to be necessary for the maturation of the central nervous system.
2. Compare non-REM sleepSee more at sleep

Word History and Origins

Origin of REM sleep¹

First recorded in 1965–70

Example Sentences

Women also entered REM sleep, characterised by high levels of brain activity and vivid dreaming, earlier than men.

From Science Daily

The neuron density of its forebrain — the region engaged with planning, sensory processing, and emotional responses, and on which REM sleep is largely dependent — is comparable to that of primates.

From New York Times

Porreca led a research team that used preclinical mouse models to evaluate sleep disruption, as the sleep architecture of mice closely matches that of people, including cycles of deep sleep, REM sleep and light sleep.

From Science Daily

If I’m lucky, I’m still in REM sleep then!

From Seattle Times

REM sleep, which happens in this phase when dreaming normally occurs, is also critical for memory formation, emotional processing, and brain development.

From Science Daily