Sleep science

Brain activity during REM

Why REM was called paradoxical sleep: an EEG that looks awake, a body that cannot move, and a pattern of regional activity that explains what dreams are like.

6 min readintermediateStrictly reviewed · cited

REM does not fit the tidy picture in which sleep gets progressively slower and quieter.

The paradox

On the EEG, REM shows mixed-frequency, low-amplitude activity: much closer to alert waking than to the slow high-amplitude waves of deep sleep. Meanwhile the body is more thoroughly paralysed than at any other point in the night.

An EEG that looks awake attached to a body that cannot move is why the state was originally named paradoxical sleep.

Beyond the EEG

Scalp EEG shows the rhythm but not the distribution. Imaging did, and the distribution is the interesting part: strong limbic and paralimbic activity, active visual association cortex, and relatively deactivated executive prefrontal regions and primary visual cortex.

The consequence is the standard dream: intensely emotional, richly visual but not perceived, and accepted without question by the part of you that would normally object.

Why this band page exists separately

The other pages here describe frequency bands. This one describes a state, because REM is not defined by a band. It is defined by the combination: EEG desynchronisation, atonia, and the eye movements it is named for. Trying to place REM on the delta-to-gamma scale is a category error, and it is one a lot of popular material makes.

Where to go next

The fuller account of the regional picture is in what happens in the brain during REM. The lucid variation on it is in gamma activity and lucid dreaming research.

Sleep-science pages summarise published research for general education. They are not a substitute for a clinician. If a sleep problem is affecting your health, speak to a doctor, and never change prescribed medication because of something you read here.

Sources and reviewed references

4 references. What these labels mean

  1. 1.Regularly Occurring Periods of Eye Motility, and Concomitant Phenomena, During SleepPeer-reviewed research

    Eugene Aserinsky and Nathaniel Kleitman (1953) · Science

    Cited for: The discovery of REM sleep and its association with dream recall, the founding observation of modern sleep science.

  2. 2.Functional Neuroanatomy of Human Rapid-Eye-Movement Sleep and DreamingPeer-reviewed research

    Pierre Maquet and colleagues (1996) · Nature

    Cited for: PET evidence that limbic and paralimbic regions are strongly active during REM while parts of the prefrontal cortex are relatively deactivated.

  3. 3.Regional Cerebral Blood Flow Throughout the Sleep-Wake Cycle: An H2(15)O PET StudyPeer-reviewed research

    Allen R. Braun and colleagues (1997) · Brain

    Cited for: That REM is not uniform activation: visual association areas are active while primary visual cortex and executive prefrontal regions are not.

  4. 4.Dreaming and the Brain: Toward a Cognitive Neuroscience of Conscious StatesPeer-reviewed research

    J. Allan Hobson, Edward Pace-Schott and Robert Stickgold (2000) · Behavioral and Brain Sciences

    Cited for: A synthesis of the brain-state differences between waking, REM and non-REM, and what they predict about the character of dreaming in each.