This article originally appeared on People.com.
We all know the silly scene of a dog, deep in slumber, energetically scuffling its paws in the mime of a fast run.
Looking from the outside, it’s hard not to wonder what’s going on in their heads. USA Network recently performed a study in celebration of its new psychological thriller Falling Water, premiering Oct. 13 at 10/9c, which explores the intersection of reality and dreams. For the study, USA asked Americans whose dreams they would like to hack if given the chance? Pets were the top of the list.
Since jumping into our animals’ dreams isn’t a reality yet, we did the next best thing and talked to Dr. Deirdre Barrett, who is a teacher and a Clinical and Evolutionary Psychologist at Harvard Medical School, about what humans know about animal dreams, and what is still uncharted.
Mesmerized by dreams at an early age, Dr. Barrett pursued a career where she could study these nightly phenomenons in humans, and she has learned quite a bit about animals along the way.
How are animal dreams different from human dreams?
Anything about what animals dream, or even if they dream, is speculative. The only two animals even suggested to have ever told their dreams to a human are the signing gorillas Koko and Michael. Researcher Penny Patterson reports that Koko occasionally signs about fantastic events, people and places she has not seen recently only upon awakening. Michael, who is known to have been captured when poachers killed his entire family, sometimes wakes up and signs “Bad people kill gorillas.”
What we do know for sure is that most mammals have a similar sleep cycle to humans, going into a deep sleep stage, in which the brain is much less active, and then into periods of activity called Rapid Eye Movement (REM) sleep, in which dreams occur for humans. That certainly makes it the best guess that other mammals are dreaming, too.
In terms of potential differences, we know that small animals, like mice, go through the sleep stages much more quickly so they would likely be having shorter, more frequent dreams. Elephants have a cycle that is longer than ours, so they would be in deep sleep longer between their dreams. Reptiles and fish don’t have the REM/non REM cycles, so they probably have dreamless sleep.
What do dogs experience when they dream?
Humans dream about the same things they’re interested in by day, though more visually and less logically. There’s no reason to think animals are any different. Since dogs are generally extremely attached to their human owners, it’s likely your dog is dreaming of your face, your smell and of pleasing or annoying you.
How about cats?
We actually know more about cats dreams, because one of the earliest sleep researchers, Michel Jouvet, destroyed the tiny area in cat brains that inhibits movements during REM sleep. Cats lay quietly through the other stages of sleep, and when REM began, they leapt up, stalked, pounced, arched their backs and hissed. They looked like they were hunting mice in their dreams.
What does it mean when my pet is asleep and its legs start moving like they are running?
They may well be dreaming they’re running. Common sleep-walking doesn’t occur during dreaming sleep, but a much more vigorous “REM behavior disorder”— a spontaneous version of what Jouvet’s experiments did, is accompanied by dreams, so the more pronounced and fast the movements, the more likely they’re acting out a dream.
Is there any way to give your pet better dreams?
The best way to give ourselves or our children better dreams is to have happy daytime experiences and to get plenty of sleep in a safe and comfortable environment. It’s a good bet this is also best for pets’ dreams.