What do dogs dream about? What to do if your dog is having a nightmare – USA TODAY

Dogs are a sleepy species. Adult dogs require more sleep than humans, averaging about 11 hours a day. Puppies require even more sleep as they grow. 
Sometimes there’s nothing cuter than a sleeping puppy, but a fit of twitches and kicks while sleeping can concern owners. It may be tempting to wake or comfort your sleeping dog if they start whining or look as if they’re trying to chase a squirrel in their sleep. Should you let a sleeping dog lie? Here’s what you need to know about doggy dreams:
Dogs certainly dream, but it’s still a bit of a mystery what they dream about. In 2001, Massachusetts Institute of Technology researchers found that animals experience dreams similarly to humans — their dreams are connected to real life experiences. 
“They probably dream about their owners and interacting with other dogs and with people that they enjoy,” says José Arce, veterinarian and president of the American Veterinary Medical Association. 
MIT conducted this survey by recording rats as they slept, observing that their unique brain activity while sleeping closely correlated with memories of running or standing still. This work, according to MIT researchers, proves that animals are able to recreate experiences in dream states. 
Studies have also found dogs experience sleep differently depending on their daily activities. After a long, active day of play, dogs sleep more and spend less time in the drowsiness stage of sleep and more time in the NREM (Non-Rapid Eye Movement) and REM (Rapid Eye Movement) phases. Dreaming occurs most during the REM sleep phase, so this means your dog dreams more when it’s active. 
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Dreams and nightmares go hand-in-hand. Bad dreams are an unpleasant experience for humans, but did you know dogs also experience them? If you’ve ever seen your dog whimper, kick or growl in their sleep, there’s a good chance they’re having a nightmare. 
Though it may be tempting to comfort a distressed sleeping dog, Arce says owners should proceed with caution.
“When a dog is growling, that’s something I wouldn’t interfere with,” Arce says. “It’s just like when a dog is seizing, you have to be very careful around their mouth because sometimes they will bite you, not on purpose, but … they don’t have any control.”
According to the Journal of Veterinary Behavior, around 6% of bites occurred while the dog was sleeping or resting. While this number may not seem large, it’s enough to think twice about petting a sleeping pup. 
While scientists know dog and human dreams are similar, there’s much to be learned in the field of doggy sleep. Arce believes technology is the key to correlating daily activity, breed and dreams. 
“Puppies seem to dream more, and for some reason older dogs seem to dream a little  bit more than the middle aged dogs,” Arce says. 
The consensus is larger dogs have longer dreams and smaller ones have shorter, and more frequent dreams. 
In years to come, further research might tell us why a Chihuahua dreams more than a German Shepherd. It might even tell us which dreams correlate with certain twitches and movements. 
“As we get artificial intelligence, and we start measuring a lot of these vitals on our pets, I’m sure we’ll find more answers,” Arce says. “Because a lot of these technologies [are] just developing as we speak and it’s getting more sophisticated.”
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