What are EEG waveform features of rapid eye movement (REM) sleep?

Updated: May 15, 2018
  • Author: Selim R Benbadis, MD; Chief Editor: Helmi L Lutsep, MD  more...
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By strict sleep staging criteria on polysomnography, REM sleep is defined by (1) rapid eye movements, (2) muscle atonia, and (3) EEG desynchronization (compared to slow wave sleep). Thus, 2 of the 3 defining characteristics are not cerebral waves and theoretically require monitoring of eye movements (electro-oculogram [EOG]) and muscle tone (electromyelogram [EMG]). Fortunately, muscle activity and eye movements can be evaluated on EEG; thus, REM sleep is usually not difficult to identify. In addition to the 3 features already named, "saw tooth" waves also are seen in REM sleep.

  • EEG desynchronization: The EEG background activity changes from that seen in slow wave sleep (stage III or IV) to faster and lower voltage activity (theta and beta), resembling wakefulness. Saw tooth waves are a special type of central theta activity that has a notched morphology resembling the blade of a saw and usually occurs close to rapid eye movements (ie, phasic REM). They are only rarely clearly identifiable.

  • Rapid eye movements: These are saccadic, predominantly horizontal, and occur in repetitive bursts.

Despite the lack of a dedicated EMG channel, the muscle atonia that characterizes REM sleep is usually apparent as a general sense of "quiet" muscle artifacts compared to wakefulness.

Clinical correlation

The duration of REM sleep increases progressively with each cycle and tends to predominate late in the sleep period into early morning. The occurrence of REM too soon after sleep onset, referred to as SOREMP, is considered pathological. However, newborns and infants enter REM more rapidly and spend a higher proportion of sleep in REM (this is true in most species and supports the theory that REM sleep is involved in brain development).

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