Have you ever looked at a sleepy pup and wondered just what was going on inside that fuzzy noggin? New research suggests they dream just like humans do.
Genetically and physically, we're about 95 percent identical to our furry companions, so it's not surprising that we've got a lot in common, professor of behavioural pharmacology and animal behaviour Dr Nicholas Dodman says.
Previous research has confirmed dogs dream, but the new study has more implications about how they dream, and what they dream of.
And just like humans, dogs can often dream of their doggy days.
As with humans, the dreaming occurs during periods of rapid eye movement (REM), where one's eyes rapidly move beneath the closed lids.
The length of time dogs spend in REM sleep changes based on their age and the size of the breed, the study has found.
For smaller dogs, they tend to dream more frequently, but have shorter dreams. Larger dogs have longer dreams, but they also dream less.
And puppies spend more of their sleep time in REM than adults.
Either way, they've both got us beat -- adults dogs sleep for around 12 to 14 hours a day, considerably longer than is considered socially acceptable for people, and they can spend around 10-12 percent of their sleep time in REM.
If you see your pup twitching in its sleep, the scientists have found an explanation for that too.
Dr Stanley Coren, a professor emeritus of psychology at the University of British Columbia, told the Daily Mail there's a switch in the brain which tells our bodies we're asleep and stops our muscles from moving.
When the switch is weak, individuals can start to act out their dreams while still asleep.
"The same thing goes with dogs," Dr Coren says. "If their switch doesn't work that well you will see the dog running or snapping at something."
The scientists aren't entirely sure if all mammals dream in the way humans and dogs do, and further studies are needed.
Dr Coren says it's likely most mammals dream in some form.
"Cats dream, horses dream, but the nature of their dreams and cycles depend on the species.
"The most important thing about the fact dogs dream is that it demonstrates that not only is the dog's brains somewhat structurally similar to the way a human brain works, it probably functions the same way," Dr Coren says. "[It's] just a primitive human brain."
Primitive or not, it's good to know that great day in the park is playing on Rover's mind as much as it is yours.