When your dog wakes you up several times a night to play “toss the stuffed toy,” you may wonder why he can’t sleep at night like everyone else in the family. Maybe he has a sleep disorder. But can non-human animals even have sleep disorders?
A sleep disorder is probably not the reason your dog wants to play in the middle of the night, but yes, animals can have some of the common sleep disorders humans suffer from. Understanding sleep disorders in animals might help us treat sleep disorders in humans.
Sleep patterns vary a lot from species to species. Cats, for example, can sleep as much as 16 hours a day (although not always at the same time their humans sleep, alas). On the other hand, elephants sleep for only about two hours a day.
Giraffes take power naps, lasting about five minutes, off and on throughout the day. Though giraffes may get as much as 4.5 hours of sleep a day, according to some estimates, only 30 minutes of that is deep sleep.
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Though there are differences in sleep patterns among different species, the physiology of sleep in animals is similar in many ways to that in humans. For example, terrestrial vertebrates, and possibly even spiders, experience REM (rapid eye movement) sleep. So, it’s not surprising that researchers have found some sleep disorders in animals, including insomnia, narcolepsy, and sleep apnea.
Many domestic animals, such as dogs, horses, and sheep, have been shown to suffer from narcolepsy, a sleep disorder in which the animal suddenly falls asleep. It seems to be especially common in dogs. Doberman pinschers and Labrador retrievers often have a heritable form of narcolepsy. An episode can be triggered by excitement, such as when the dog is offered food or a favorite toy. Mice can have narcolepsy, too. Though anticipating food can do the trick for mice, little Mickeys, and Minnies sometimes drop off unexpectedly when they get overexcited about social encounters or running on a wheel.
It’s tricky to know if an animal has insomnia because insomnia means you want to sleep but can’t, and there’s no way to ask an animal if they are trying to get a good night’s sleep but can’t stop replaying that embarrassing incident at the dog park this afternoon.
Yet there is some evidence that rats can suffer from insomnia — and for the same reasons humans often can’t sleep: stress and anxiety. In one study, male rats were moved from a familiar cage to a dirty cage that another male rat had recently occupied. These rats appeared to experience insomnia.
Obstructive sleep apnea, though not terribly common in non-human animals, can occur in dogs and other animals as well. In part because of their large soft palates, English bulldogs are so prone to the disorder (even when they’re not obese) that they’re often used to study the anatomy associated with sleep apnea and to develop treatments.
Mice make useful models for the study of sleep apnea, too, particularly when it comes to factoring in details such as age and obesity. (Mice are astonishingly like humans in many ways.)
If your pet seems to have a sleep disorder, you can check with your veterinarian to find out if you’re dealing with a sleep problem, a behavior problem, or just a cat. Meanwhile, scientists are studying animal sleep disorders in the hopes of better understanding our own sleep problems.
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