Can Animals Dream?

Oct 26, 2026

Can Animals Dream?

Your dog twitches its paws, lets out a small whimper and its eyes flutter beneath closed lids. Your cat chirps softly and its tail flicks once. Are they dreaming? The scientific answer, based on decades of sleep research, is almost certainly yes — at least for mammals and birds. Researchers at MIT and other institutions have found that the sleeping brains of animals replay the neural activity of their waking experiences in ways that strongly parallel what happens in dreaming humans.

The Science: What REM Sleep Reveals

We cannot ask an animal what it dreamed about — but we can measure what its brain does during sleep, and the evidence is striking.

What REM sleep is and why it matters

Sleep in mammals is divided into two broad phases: non-REM (NREM) sleep, which is deep and restorative, and REM (rapid eye movement) sleep, during which the brain becomes highly active — almost as active as it is when awake. In humans, REM sleep is when the most vivid and memorable dreams occur. When people are woken from REM sleep, they are far more likely to report dreaming than when woken from NREM sleep. The key insight from animal research is that the brains of many animals show the same REM and NREM cycle — and during REM, the same neural patterns fire as during waking activity.

The rat maze experiment

One of the most compelling pieces of evidence came from MIT researchers Matthew Wilson and Kenway Louie, who trained rats to run through a maze while recording the precise firing patterns of neurons in the hippocampus — the brain region associated with memory and spatial navigation. When the rats later slept, the same neuron sequences fired during REM sleep, often at the same speed and in the same order as during the maze run. The match was so precise that the researchers could identify exactly where in the maze a rat was “replaying” while asleep. This is the closest science has come to directly observing an animal dream.

Which Animals Dream — and Which Probably Don’t

REM sleep is the best available marker for dreaming — and it is far more widespread across the animal kingdom than scientists once assumed.

A fascinating 2022 discovery found that jumping spiders — invertebrates — show REM-like eye movement patterns during sleep, raising the possibility that dreaming evolved far earlier in animal history than previously thought. Zebra finches, studied by biologist Daniel Margoliash at the University of Chicago, appear to use REM sleep to practice their songs — their brains replay the neural sequences of singing during sleep.

Do Dogs and Cats Dream?

The evidence for dreaming in dogs and cats is strong — and what you see when your pet twitches in its sleep is almost certainly a dream in progress.

Dogs experience both NREM and REM sleep, with REM making up roughly 12% of their total sleep time. During REM, dogs show the same behavioural signs seen in humans — rapid eye movements, irregular breathing, muscle twitches and occasional vocalisations. Harvard psychologist Deirdre Barrett, who has studied animal dreaming extensively, suggests that dogs most likely dream about their daily experiences: running, playing and interacting with the people they are close to. Researchers who temporarily disabled the pons — the brain structure that paralyses muscles during REM sleep to prevent acting out dreams — found that dogs began to physically act out behaviours during sleep, reinforcing the idea that those movements correspond to dream content.

Cats show similar REM patterns, and cat owners will recognise the signs: paw twitching, tail flicking, whisker movement and occasional vocalisations during sleep. Smaller dogs tend to enter REM sleep more frequently than large breeds, and puppies and kittens — who have vastly more new experiences to process — spend more time in REM sleep than adults.

What Do Animals Dream About?

We cannot know for certain — but the evidence strongly suggests that animals dream about their own waking experiences.

The MIT rat maze research showed that animals replay specific memories during REM sleep — a function that appears to serve memory consolidation, the same role dreams are believed to play in humans. Rather than abstract or imaginary scenarios, animals most likely experience replays of recent events: a dog re-running a morning walk, a cat re-stalking a bird it watched through the window, a rat navigating a familiar path. Whether animals experience the full narrative quality of human dreams — with characters, plot and emotional resonance — remains unknown and is likely beyond what current neuroscience can resolve. Some researchers suggest that animals without the language structures humans use to construct narrative may experience something closer to vivid sensory replay than story.

Further reading on animal sleep and cognition:

• AKC – What Do Dogs Dream About? — overview of the research on canine REM sleep and dreaming
• Science ABC – Do Animals Dream? — broader look at REM sleep across the animal kingdom, including the 2022 jumping spider study

FAQ

Should I wake my pet if it seems to be having a nightmare?

Generally no. The old advice “let sleeping dogs lie” has some merit here — waking a dog or cat from deep REM sleep can startle them and they may react defensively before fully orienting. If your pet seems distressed, call their name softly from a distance rather than touching them suddenly. Most episodes pass within a minute or two.

Why does my dog twitch so much while sleeping?

The muscle twitches and leg movements during sleep are the physical expression of dream activity — the pons normally suppresses full movement, but smaller muscle groups still respond. Puppies and young dogs twitch more than adults because they spend more time in REM sleep processing their many new experiences.

Do fish dream?

Fish do appear to have sleep states, and some research has identified REM-like phases in certain species. Whether this constitutes dreaming in any meaningful sense remains genuinely unknown — the evidence is much less developed than for mammals and birds.

Can animals have nightmares?

Probably yes — at least animals with rich enough emotional lives to experience fear. Dogs rescued from abusive situations, animals that have experienced trauma, and pets with anxiety are observed to have more disturbed, active sleep than calmer animals. While we cannot confirm the content, it is reasonable to infer that negative experiences can be replayed during REM sleep just as positive ones are.

This guide is for general information only and is not a substitute for advice from a qualified veterinarian. If your pet seems unwell, contact your vet.

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