If you’ve ever looked over at your soundly sleeping dog or cat only to see their limbs flailing all over the place, their whiskers twitching as they make strange sounds, you probably just thought they were dreaming. As pet owners, we tend to assume our beloved fur babies experience the world exactly as we do. But do animals actually dream, and if so, why do they dream, and what do they dream about?
Dreaming is one of the most intriguing and mysterious aspects of sleep. Yet it’s something we all go through — some of us on a fairly regular basis. In simple terms, dreams can be defined as stories our brain cooks up while we are sleeping. But why do our minds stay wide awake when our bodies are resting? Experts suggest that dreaming plays a vital role in memory and learning, but is it human-specific?
Much of our insights into what happens in the lesser-known land of nod come from our own experiences and what others tell us about their nightly adventures. Sadly, our pets cannot wake up and say, ‘You’ll never guess what I just dreamed about!’ So, instead, we have to take what science and observation have taught us and use it to try to figure out what’s happening to Fido when he’s peacefully (or not so peacefully) slumbering.
One thing we know for sure is that, in humans, dreaming happens when we hit something known as REM or rapid eye movement sleep. Basically, not all sleep is created equal. Throughout the night, we cycle between different sleep stages, some deeper and more restful than others. These stages are indicated by changing patterns in brain activity. REM sleep is a lighter kind of sleep, and it’s when our minds are the most active.
Studies on the brain activity of sleeping pets show that most mammals and even some kinds of reptiles and birds experience REM sleep. This makes it highly likely that they do dream. In fact, when you see your pet twitching and making sounds in their sleep, this is REM sleep at work. You’ll likely be able to see their eyes darting to and fro under their eyelids as their mind plays out a story, and they track different objects in dreamland.
The amount of REM sleep each animal experiences depends on how much they sleep and their individual sleep patterns. Humans, for instance, have sleep cycles of around 70 to 120 minutes, and they will move through REM and non-REM sleep several times. On the other hand, dogs have shorter 45-minute sleep cycles with two REM stages of about six minutes each. Cats, with their love of long naps (they typically sleep between 12 and 16 hours a day), can have up to eight hours of dream-filled REM sleep!
No one can know for sure what their four-legged friend dreams about. However, actions they make in their sleep and the accompanying sounds offer us some pretty useful clues. Usually, during REM, the part of the brain that would have us acting out our dreams is effectively blocked, but sometimes, this mechanism can falter, and movement happens.
Our best guess is that, like human dreams, dog ones are likely a reflection of their daily lives. They probably dream about things they are interested in and are emotionally attached to. So if your pup’s legs are moving at speed, chances are they are busy dream-chasing that squirrel at the park, fetching their ball, or happily playing with their favorite people.
We actually know a bit more about cat dreams than dog ones because, in one study, a researcher completely turned off the part of the brain that keeps them still in sleep. He was then able to observe cats acting out their dreams with behaviors indicative of hunting and fighting, such as chasing, moving their paws around, arching their backs, and hissing.
Again, as in humans, such dreams are linked to memory and learning. Interestingly, studies have also shown that kittens experience more REM sleep than older cats, which supports experts’ ideas on why we dream — they have a lot more to learn and remember.
It makes sense to most pet parents that dogs and cats dream, but what about other animals? Well, we know for sure that they experience REM, so they must do. And by observing birds and lizards, scientists have come to the conclusion that they also dream to learn. For instance, young birds rehearse songs they have learned from adult ones in their sleep, and bearded dragons cycle through deep and REM sleep like mammals.
With all these sleep similarities between people and their pets, we can conclude that cats and dogs probably also experience the occasional nightmare. It will likely be obvious if this is the case with your pet. You will see them cowering, whimpering, growling, hissing, or otherwise seeming upset while they sleep.
While it may be tempting to wake up and comfort your beloved friend, you should resist the impulse. Pets that are startled out of sleep may lash out. Just keep in mind that nightmares, like dreams, are a natural learning process and don’t last all that long anyway.
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