Do cats dream? What happens in their brain when their paws twitch in their sleep
Almost certainly, yes. Cats have REM sleep, the stage in which people dream, with brain activity very similar to ours, and classic experiments on cats showed hunting behaviour during that stage. What we cannot know is exactly what they dream about, because they cannot tell us.
Two kinds of sleep, just like us
Cat sleep, like that of almost all mammals, alternates between two kinds of stage. In slow-wave sleep, brain activity slows down, breathing is regular and the body is relaxed but keeps some muscle tone: this is the curled-up cat that opens one eye when it hears the bag of biscuits. In REM sleep, named after the rapid eye movements, the brain becomes active in a way very similar to when it is awake, while the body’s muscles are almost paralysed. In people, this is the stage in which we have our most vivid, story-like dreams. In adult cats, REM phases are shorter than slow-wave phases, and they occur several times during each nap.
The experiments that pointed the way
Much of what we know about REM sleep was discovered precisely in cats. In the late 1950s and the 1960s, the French neuroscientist Michel Jouvet, in Lyon, studied which area of the brainstem produces the muscle paralysis of REM sleep. When that area was damaged, the cats, fast asleep and unresponsive to stimuli, would raise their heads, stalk, hiss or make attacking movements, as if acting out what they were dreaming. Jouvet interpreted this as the expression of dream activity. These were experiments from an era with different ethical standards, and they would not be done that way today, but they left a solid conclusion: during REM sleep, a cat’s brain generates something like scenes.
So what does it dream about?
Here we have to be honest: we do not know. What was seen in those experiments was typical cat behaviour, such as stalking, hunting or defending itself, which suggests that its dreams have to do with what it does while awake. In rats, more recent studies have found that during sleep the brain replays sequences of activity resembling routes the animals took during the day, which supports the idea that sleep helps consolidate memory. It is reasonable to think that something similar happens in cats, but any specific claim about whether your cat dreams about you, its food or the neighbour’s cat is pure speculation.
How to tell it is in REM sleep
A cat in REM sleep is usually lying on its side or fully stretched out, completely relaxed, with slack neck muscles. This is when you see the little twitches of the whiskers, ears and paws, rapid eye movements under the eyelids, the odd whimper or muffled meow, or mouth movements as if it were chewing or suckling. These are brief episodes of a few minutes that alternate with calmer phases. It is entirely normal and does not mean it is having a nightmare or is uncomfortable. Kittens spend much more time in REM sleep than adults, which is why their naps look so busy.
Sleeping with one eye open
Much of what looks like sleep in a cat is actually watchful dozing: it is lying down with its eyes closed or half open, but its ears swivel towards every sound and it can be on its feet in a second. It is an adaptation of an animal that is both a hunter and prey for larger animals. That is why cats choose so carefully where to sleep: high places, spots where their back is protected or with a good view of the room, and they move around depending on the time of day and the temperature. Only when a cat feels completely safe does it allow itself deep sleep, lying on its side or belly up. A cat sleeping like that in the middle of the living room is saying, in its own way, that it trusts the home and the people in it.
Should you wake it?
There is no need, and it is better not to. A cat woken suddenly from deep sleep may take a second to get its bearings and react with a start or a swipe, especially if it is touched. If you need to wake it, call its name softly from a little way off. Respecting its rest is part of its welfare: an adult cat sleeps between 12 and 16 hours a day, and kittens and older cats even more. Having quiet, warm, raised places to sleep, away from the busy parts of the house, helps it rest well. And if it sleeps on top of you, that is a good sign of trust.
When the movements are not a dream
Brief twitches during sleep are normal; a seizure is something else. During a seizure the cat is usually rigid or jerking rhythmically all over, may drool, urinate or defecate, does not respond when you call it and, afterwards, stays disoriented, clumsy or blind for a while. Seizures can also happen while the cat is awake. If in doubt, film it on your phone and show the vet, which is the most useful way to tell the two apart. A seizure lasting more than five minutes, or several in a row, is an emergency, as is the first seizure in a cat that has never had one before.
What it tells us about cats
It is no coincidence that cats sleep so much like we do: it is a heritage shared by mammals. Nor is spending so many hours asleep a sign of laziness; it is the way of life of a hunter that burns a lot of energy in short bursts. If a cat suddenly starts sleeping much more than usual, sleeping less and wandering around at night meowing, or swapping its usual spots for hiding places, this is not about dreams: it is a change in behaviour that deserves a vet visit, because it may be caused by pain, illness or, in older cats, cognitive decline.
Cats have REM sleep, the stage in which people dream, and Michel Jouvet’s experiments in the 1960s showed sleeping cats stalking and attacking as if acting out their dreams. They almost certainly dream, probably about cat things, but the exact content cannot be known. Brief twitches are normal; a seizure is not.
Educational content from Michipedia, translated from the Spanish original. It does not replace the advice of a vet or a feline behaviour specialist. Every cat is an individual.