Do Animals Dream?

If you share your home with a dog or cat, you've almost certainly seen them do it: paws twitching, eyes moving beneath closed lids, small sounds escaping as they sleep. It looks like dreaming. And the evidence suggests that it is.

REM sleep is not unique to humans

Dreaming is associated with REM sleep — the sleep stage characterised by rapid eye movements, muscle atonia (paralysis), and intense brain activity. And REM sleep is not unique to humans. It has been identified in all mammals studied and in many birds. The more complex the nervous system, the more evidence of REM-like sleep states.

What the evidence shows

Rats: In landmark studies, researchers recorded the hippocampal activity of rats while they ran mazes, then monitored the same brain patterns during sleep. The rats' brains replayed the maze sequences in their sleep — the same neurons firing in the same order — at roughly the speed they had originally run them. The rats appeared to be literally replaying their experiences in sleep.

Dogs: Dogs show all the physical signs of REM sleep — eye movements, twitching, movement, vocalisation. Given the similarity of canine sleep architecture to human sleep, the inference that dogs experience something like dreaming is considered well-supported.

Birds: Some bird species, particularly songbirds, appear to rehearse their songs during sleep. The neural patterns associated with song production are active during sleep in ways that suggest the birds are practising in their dreams.

Invertebrates: More recently, evidence of REM-like sleep states has been found in octopuses, which show dramatic colour and texture changes during sleep — possibly reflecting visual dreaming, which would be remarkable given their radically different nervous system architecture.

What animal dreaming tells us about ours

The evidence that many animals dream — and that the content appears to involve replaying experiences — strongly supports the memory consolidation theory of dreams. Dreams appear to be, at least in part, how the brain processes and consolidates experiences from waking life. This function is ancient, shared across species, and tied to the basic requirements of learning and adaptation.

Remnance tracks your dream content alongside your daily experiences — reflecting the same memory-consolidation process that plays out across the animal kingdom every night.