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Claim check

Do octopuses dream?

Early evidence

Real findings exist, but too few or too new to settle the question.

Octopuses have a sleep stage with the behavioural and neural hallmarks of REM sleep, including rapid skin-colour changes and wake-like brain activity. Whether anything is experienced during it is unknown, and no available method could find out.

The claim as it circulates

“Octopuses dream, and you can watch the dream play across their skin.”

Where you may have met it: Viral footage of a sleeping octopus changing colour; Nature documentary narration; Science media coverage of two sleep studies

Taking it apart

What was claimed
That the colour changes visible in a sleeping octopus are the outward signs of a dream.
What was actually observed
Continuous filming of four octopuses showed sleep alternating between a pale, still state and brief active episodes with rapid colour change, eye movement and twitching, recurring roughly every half hour. A later study recorded brain activity at the same time and found the active phase resembled waking rather than quiet sleep, with the skin cycling through patterns the animal also uses awake.
What the evidence supports
That octopuses have two-stage sleep, and that the active stage is neurally active rather than merely twitchy. Structurally, it is a close parallel to REM sleep — arrived at independently, in an animal on the far side of the tree of life.
What it does not support
That octopuses have dream experiences. The same observations are equally consistent with a nervous system rehearsing patterns with nothing being experienced. Small samples, two different species, and no way to ask the animal.

Where researchers disagree

Researchers agree on the observations. What they cannot agree on — because no experiment currently distinguishes the possibilities — is whether a REM-like state in an invertebrate implies anything like subjective content. The dispute is as much philosophical as empirical, and the researchers involved are noticeably more cautious than the coverage of their work.

The most defensible summary is narrower than the headline and stranger than it: a mollusc, whose lineage separated from ours more than half a billion years ago, independently evolved a sleep cycle that looks like ours from the outside. That is worth more attention than the dream question, which is currently unanswerable.

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The claims underneath

Each one carries its own evidence, scope and caveats. Expand any of them to reach the studies.

Octopuses have a sleep stage that looks like REM sleep

Well supported

Good evidence backs this, though some details remain open.

Octopuses cycle between a quiet sleep state and brief active episodes involving rapid skin-pattern changes, eye and arm movement, and wake-like neural activity. The structural resemblance to vertebrate REM sleep is clear; nothing about subjective content is established.

Who this applies to
two octopus species studied so far
Studied in
Octopus insularis, Octopus laqueus

You may have heard

“Octopuses dream, and you can watch them dreaming.”

The colour changes during active sleep are real and were filmed. What they mean is unknown. The same evidence is equally consistent with the nervous system rehearsing patterns with nothing being experienced at all — and no design available today can tell the difference.

Why we rate it this way, and what the caveats are
Well supportedHigh confidence

Behavioural characterisation in one species and simultaneous neural recording in another, converging on the same picture. High confidence in the sleep state; the dream question is a separate matter and is not claimed here.

How far it can be extended

Two independent laboratories found the same two-stage pattern in different species, which suggests it is a feature of octopuses rather than of one animal.

Caveats

  • Small samples, as is normal for this work.
  • A sleep stage with REM-like structure does not establish that anything is experienced during it.
  • Two species; octopuses vary widely.

Still unanswered

  • Does active sleep serve memory consolidation, as REM sleep appears to in vertebrates?
  • Could any experiment address dream content in an animal that cannot report?

Last reviewed 2026-08-09

The evidence (2 studies)

Go deeper

Octopuses

A second, independent invention of a complex mind — with two-thirds of its neurons in its arms.

Last reviewed 2026-08-09