When a sleeping dog twitches and barks, are they really dreaming about chasing squirrels or Frisbees? Very likely!

Animal behavior expert, Dr. Stanley Coren, from the University of British Columbia, says dogs experience both slow-wave sleep and REM sleep, the deeper stages where dreams occur in humans. And research shows the twitches and vocalizations you see as they’re sleeping are reactions to what’s occurring in their dreams.

But the twitching and running is most likely to happen in puppies and older dogs. Dr. Coren says it’s down to an area of the brainstem, which contains two “off” switches that curtail movement during the sleep cycle. If one or both “off” switches aren’t fully developed, like in a still-growing puppy, or have weakened with age, the dog’s muscles won’t be completely turned off.

So, if your dog twitches and yips while napping, chances are they’re just dreaming about a squirrel, a Frisbee, or playtime with YOU.