Written by Dogoos Editorial · Editorial team

Watch your dog drift off after a long afternoon walk and you may notice something tender unfolding behind those closed eyes. The paws twitch, a leg paddles softly through the air, and a muffled woof escapes as if a tiny adventure is playing out somewhere we cannot follow. It is almost impossible to watch that and not decide you know what is going on in there. That dogs dream at all is a fair inference from everything we can measure. What they dream about is another matter entirely, and the better story.

The sleep itself has been measured properly, in ordinary pet dogs, without surgery, and two of its stages get muddled constantly. Deep, slow wave sleep is the quiet one: measured in people, the brain’s oxygen use falls about 25 per cent below waking. Rapid eye movement sleep, REM, is the vivid dreaming stage, and in that same study oxygen use during REM was practically that of the awake state.

So REM is the busy stage, not the restful one, running inside a body gone deliberately slack: a cluster of cells in the brainstem cuts postural muscle tone so that none of us act out our dreams. What it spares is the giveaway. In normal dogs the eyes, face, toes, tail and diaphragm carry on moving. The twitching paw is not the brake leaking. It is what the brake was built to leave running. So what is playing while the body lies still?

In rats, where single brain cells can be recorded, patterns laid down while the animal ran a track were replayed during REM at roughly the speed they first happened. Nobody has listened to a dog that closely. In dogs we have the consequence, not the picture: after a learning session their sleeping brain activity shifted in step with how much better they performed on waking, the first evidence that a dog’s very human social learning may lean on sleep to bed in. Which is where the loveliest claim about dogs lives.

You will read almost everywhere that they dream of their owners’ faces, voices and scents, usually dressed up as a finding. It is not one. It is speculation that got repeated until it set hard. The reasoning is sensible enough: the food bowl, the garden door, the lead off the hook, you are in nearly every moment of your dog’s day that mattered, so if the day is replayed you are all over it. Sensible is not measured. Nobody has recovered the content of a dog’s dream, and with today’s tools nobody can.

There is real variation to enjoy, just not the version that gets repeated. A dog’s cycle runs about twenty minutes, twelve of drowsy non REM and six of REM, against nearer ninety in us, so dreaming comes round perhaps three times an hour. Whether a chihuahua differs from a deerhound is a fair question with a flat answer: the field’s own review says the effect of body size on dog sleep has never been systematically investigated, so the tidy line about small dogs dreaming in quick bursts is somebody’s invention. Age does show up.

Among puppies of two to six months, the younger ones spend proportionally more of their sleep in REM. Old dogs go the other way: less REM overall, more sleep by day, more waking at night. The grey muzzle on the rug is not dreaming more than the puppy. It is sleeping worse. So, beyond the pleasure of watching, protect the sleep, because where a dog sleeps changes how much of it they get: dogs sleeping indoors were reported to spend 80 per cent of the night asleep, against 60 per cent outdoors and unfenced. Dreaming sleep turns up when a dog feels safe.

Give yours a quiet spot of its own, which is roughly what the RSPCA advises: a cosy place in a quiet room that is theirs, and children taught to leave them alone in it. And let sleeping dogs lie. Disturbing a resting dog is a documented bite circumstance, though the numbers are small and come from one clinic’s caseload: eight of 77 bitten children aged six to seventeen, and one of 34 under six. If the paddling ever worries you, do not judge it yourself.

Film it and show your vet: in one published case it took 31 hours of EEG to establish that a sick dog’s violent paddling came only with REM and at no other stage, and was not a seizure. Otherwise, take a quiet moment and enjoy the sight. You are watching a brain sort through a day that you were in. What it makes of you in there is the one part you do not get to see.

Sources & further reading

  1. Sleep in the dog: comparative, behavioral and translational relevance — Current Opinion in Behavioral Sciences 2020 (2020-06-01)
  2. The interrelated effect of sleep and learning in dogs (Canis familiaris); an EEG and behavioural study — Scientific Reports 7:41873 (Nature Portfolio), by Kis et al. (2017-02-06)
  3. Temporally structured replay of awake hippocampal ensemble activity during rapid eye movement sleep — Neuron 29:145-156 (Cell Press), by Kenway Louie & Matthew A. Wilson (MIT) (2001-01-01)
  4. Cerebral O2 metabolism and cerebral blood flow in humans during deep and rapid-eye-movement sleep — Journal of Applied Physiology 1991 (1991-06-01)
  5. Electroencephalography of rapid eye movement sleep behavior disorder in a dog with generalized tetanus — Journal of Veterinary Internal Medicine 2023 (2022-12-01)
  6. Developmental features of sleep electrophysiology in family dogs — Scientific Reports 11:22760 (Nature Portfolio), by Reicher, Bunford, Kis (2021-11-23)
  7. Behavioral assessment of child-directed canine aggression — Injury Prevention 2007 (2007-10-01)
  8. Children & Dogs - How They Can Live Together — RSPCA (rspca.org.uk)