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.

Why the tidy version lasted so long

The equation held for a while because it was clean, it fitted the first strong finding, and the counter-evidence is harder to gather: collecting non-REM reports means waking people at points in the night where they are groggy and their reports are short.

That is worth noticing as a pattern rather than a piece of history. A finding that is easy to collect will look stronger than one that is hard to collect, and the correction usually arrives late and quietly.

The consequence for your own record

Two things follow directly.

Log naps. Nap dreams are frequently non-REM reports and they look thin beside a morning dream, which is exactly why most people never write them down and why almost nobody has a record of their own.

Log the short entries. A three-line, thought-like, undramatic report is not a failed dream. It is what a non-REM report looks like, and a journal made only of the vivid ones is a record of your late REM periods rather than of your dreaming.

Practice

Log any dream you recall from an early waking as well as your usual morning one. Compare them for length, strangeness and story. The difference between the two is the distinction this lesson is about.

Self-check

What stuck?

Recall only, nothing here is graded, and none of it gates the lesson.

  1. 1. How do non-REM dream reports typically differ from REM ones?

  2. 2. What does that mean for a dream recorded from a nap or from early in the night?

  3. 3. What is still open in this area?

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.