REMrelated

REM-related is an adjective used in sleep science to describe phenomena, symptoms, or conditions linked to rapid eye movement (REM) sleep. REM sleep is the sleep stage that typically occurs about 90 minutes after sleep onset and recurs in cycles; it is marked by rapid eye movements, vivid dreams, desynchronized brain activity, and decreased muscle tone.

REM-related topics include both normal features of REM and clinical conditions in which REM processes are altered. Examples include REM density and REM latency, which quantify the frequency of rapid eye movements within REM periods and the time to first REM, respectively. Clinically relevant REM-related disorders include REM sleep behavior disorder (RBD), in which diminished REM atonia allows dream enactment, and phenomena such as sleep-onset REM periods seen in narcolepsy, which involve intrusion of REM-like physiology into wakefulness. REM-related disturbances of dream experience, mood, or autonomic regulation are also studied.

Assessment of REM-related phenomena typically relies on polysomnography to record EEG, EOG, and EMG and identify REM periods, along with dream reports and autonomic measures. Pharmacological, circadian, and ageing factors can influence REM sleep, yielding REM-related effects that are important in research and clinical contexts. The term is general and descriptive, used to group findings tied to REM sleep rather than to designate a separate disorder.