When humans sleep, it’s pretty likely we’ll dream—but we’re not the only ones who do.
Dogs experience a similar dream state to humans, drifting in and out of REM sleep. But just what happens when Rover shuts his eyes?
Psychologist Stanley Coren, author of Do Dogs Dream?: Nearly Everything Your Dog Wants You to Know and professor emeritus at the University of British Columbia, says that Rover is likely to dream of situations that mirror his everyday life. So that would be sniffing the trash, eating your leftovers, and looking very excited whenever you get home.
A 2014 study in Frontiers of Behavioral Neuroscience found that beagles who received sleep aids could force themselves awake when emergency stimuli was provided—which was then applied to humans. To get this data, the beagles had telemetry implants that read their eye movements and electrical activity in their brains. The researchers chose to use dogs because their habits closely mimic humans’ and because of their sensitivity to sound.
“Our brains are similar [to dogs], our neurochemistry is the same, and our reflexes and memory are ‘wired’ in like manner,” wrote veterinarian Dr. Nicholas Dodman, whose new book, Pets on The Couch, delves into animal psychiatry. “Dogs are probably dreaming too when they are in REM sleep, although no dog has ever told anyone about a dream he’s had.”
“It is really quite easy to determine when your dog is dreaming without resorting to brain surgery,” Coren says in Psychology Today. “After a period of about 20 minutes for an average-sized dog his first dream should start. You will recognize the change because his breathing will become shallow and irregular. The eyes are moving [behind closed lids] because the dog is actually looking at the dream images as if they were real images of the world.”
Coren notes that dogs have a very similar sleep cycle—and dream state—to humans.
When they first start snoozing, dogs enter slow wave sleep, where they become mentally rested, but their body is still in physical alert mode. After twenty minutes they enter REM sleep, and their bodies relax, but their mind engages. Behind their eyelids, their eyes are darting around, looking at things that aren’t there, the very definition of a dream. This is similar to how humans sleep—except we take longer to get to the REM stage.
Smaller dogs get more bouts of REM sleep, but big dogs have longer dreams, according to Coren. Dreaming is fairly unique to mammals—fish and insects don’t experience this at all.
So in all likelihood, Rover’s spending his dog nap reliving the treats you fed him and how great the squirrels were—not how to take over the world.