The Paws Are Running, But the Dog Is Asleep
Most dog owners have watched it happen: a sleeping dog whose legs begin to paddle, who makes small muffled sounds, whose eyes flicker behind closed lids. It is one of the most endearing things a dog does — and it raises a question that science has now moved considerably closer to answering. Do dogs dream? The evidence strongly suggests they do.
How Dog Sleep Works: The Basic Architecture
Sleep is not a single state. Both humans and dogs cycle through distinct phases, and understanding this architecture helps explain what is happening when your dog twitches.
Dogs, like humans, experience two primary types of sleep: slow-wave sleep (SWS) and rapid eye movement sleep (REM). They cycle through these stages repeatedly throughout a sleep period, though the timing differs from humans.
Slow-Wave Sleep
In slow-wave sleep, the brain is relatively quiet and the body is relaxed but the dog can still rouse quickly. This is a restorative phase important for physical recovery. Dogs typically enter slow-wave sleep soon after falling asleep and may spend longer proportions of their total sleep here than humans do.
REM Sleep
REM sleep is where things get interesting. During REM, brain activity increases dramatically and closely resembles the patterns of a waking brain. This is the phase associated with dreaming in humans, and EEG (electroencephalogram) studies in dogs confirm the same characteristic brain wave patterns. It is during REM sleep that the twitching, paddling, vocalising, and eye movement you observe in your dog occurs.
The Evidence for Dreaming
In a landmark set of experiments at MIT, researchers Matthew Wilson and Kenway Louie recorded hippocampal activity in rats as they ran a maze, then recorded the same activity during subsequent sleep. The neural firing patterns during REM sleep closely mirrored the patterns from the maze experience — strongly suggesting the rats were replaying the day's events in sleep. The hippocampus, the brain region involved in memory consolidation, is structurally similar across mammals.
Neuroscientist Matthew Walker, in his widely cited work on sleep science, has argued that the case for dreaming in dogs is strong on neurological grounds. Dogs have the same sleep architecture, the same REM phase, the same associated brain activity, and the same muscle twitching caused by incomplete motor cortex suppression during REM.
What dogs dream about is, of course, impossible to know with certainty — but the most reasonable hypothesis is that they replay experiences: runs, interactions with other dogs, play sessions, and the emotional texture of their day.
Why Dogs Twitch in Their Sleep
During REM sleep, the brain sends movement signals — you are essentially watching your dog act out their dream. In adult humans, a mechanism called REM atonia largely paralyseses the voluntary muscles to prevent acting out dreams. This suppression is not complete in dogs, which is why you observe visible movement.
Small dogs and puppies tend to twitch more visibly and more frequently during sleep than large adult dogs. This is because the brainstem mechanism responsible for suppressing movement during REM is less mature in puppies and appears to be more active in smaller breeds. Older dogs may also show more movement during sleep than they did in middle age.
How Much Sleep Do Dogs Actually Need?
Adult dogs sleep considerably more than adult humans — typically between 12 and 14 hours per day, though this varies significantly by age, breed, activity level, and health status.
- Puppies may sleep up to 18 to 20 hours per day, as sleep is critical for neural development and physical growth
- Senior dogs often increase their sleep duration as metabolic rate and activity levels decline
- Working breeds and highly active dogs may sleep more heavily after exertion
- Dogs are polyphasic sleepers — unlike humans who consolidate sleep into one long block, dogs sleep in multiple shorter periods throughout the day and night
Should You Wake a Dreaming Dog?
The old advice "let sleeping dogs lie" has neurological merit. Waking a dog during REM sleep disrupts the memory consolidation and emotional processing that sleep provides. It can also disorient a dog, particularly a rescue dog or one prone to anxiety, who may startle and react defensively before fully registering where they are.
If your dog appears distressed during sleep — vocalising, trembling or moving persistently — it is generally better to call their name softly from a distance rather than touching them. Most dogs will rouse naturally from a dream cycle within a short time.
When Sleep Changes Are Worth Discussing With Your Vet
- A sudden significant increase in sleep duration, particularly in a younger adult dog, can indicate illness, pain, hypothyroidism, or anaemia
- Violent, sustained movement during sleep — more intense than typical dreaming twitches — may be seizure activity, which looks different from REM behaviour and warrants urgent veterinary assessment
- A dog who appears confused or disoriented after waking, repeatedly or over time, should be evaluated for cognitive dysfunction syndrome, particularly in senior dogs
- Snoring that is new, very loud, or accompanied by laboured breathing during sleep may indicate a respiratory issue
- Changes in sleep patterns following a stressful event or environmental change are often normal, but persistent sleep disruption is worth mentioning at your next veterinary appointment
Dreaming is not a quirk or an anthropomorphic projection — it is a fundamental part of how mammalian brains process experience. When your dog runs in their sleep, the evidence strongly suggests something real is happening in that brain. Treat their sleep as seriously as your own.