Sleep science

REM versus non-REM dreams

"REM equals dreaming" is the tidy version taught for decades. It is wrong, and the correction matters for anyone keeping a journal.

6 min readintermediateStrictly reviewed · cited

After REM was discovered in 1953 and linked to vivid dream reports, the field settled on a simple equation: REM is dreaming, non-REM is not.

Then people kept collecting reports from non-REM awakenings, and kept getting dreams.

What the difference actually is

Reports from non-REM sleep tend to be:

  • Shorter.
  • Less visual and less narrative: more thought-like, more static.
  • Less emotional.
  • Less bizarre.

Reports from REM tend to be longer, more story-shaped, stranger and more emotionally charged. But these are distributions that overlap, not two different phenomena. A long vivid non-REM dream is unusual, not impossible.

Why it matters to you

Two practical consequences for a journal:

  • A dream from a nap or from early in the night is not less real because it does not look like a late-night REM epic. It is a normal non-REM report.
  • Sleep-onset imagery is its own thing again: the hypnagogic state, which has its own page.

The state of the argument

Whether non-REM dreaming is genuinely separate, or whether some non-REM periods carry "covert" REM-like processes, is still open. What is settled is that the tidy equation was too tidy.

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

3 references. What these labels mean

  1. 1.A Review of Mentation in REM and NREM Sleep: "Covert" REM Sleep as a Possible Reconciliation of Two Opposing ModelsPeer-reviewed research

    Tore Nielsen (2000) · Behavioral and Brain Sciences

    Cited for: That dreaming occurs in non-REM sleep as well as REM, and that reports from the two states differ in length and vividness rather than in kind.

  2. 2.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.

  3. 3.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.