Have you ever wondered what your favorite animal does when it’s sleeping? Whether it’s a lion lounging on the savanna or a leopard crawling into a tree, animals often sleep in the most unexpected of places. From giraffes to whales, here are some of the world’s most interesting facts about how animals sleep.
Lions spend up to 20 hours per day sleeping and resting. They sleep for short periods during both day and night. Their naps rarely last longer than 20 minutes, but they can go four days without sleep if they have to stay vigilant.
Giraffes sleep between five and 10 minutes in any 24-hour period—that’s the least amount of sleep of any mammal! Other than humans, giraffes are the only animals that do not go through cycles of deep sleep and rapid eye movement (REM) sleep.
Elephants spend anywhere from four to six hours per day sleeping and resting. Like giraffes, elephants do not go through cycles of deep and REM sleep; however, their REM sleep is much deeper than ours. During this time, it is believed that elephants dream about their past experiences.
Humans need eight hours of sleep a night—or so the common wisdom goes. But what about animals? Here’s a brief guide to animals and their sleep cycles.
Cats and dogs typically need between 12 and 14 hours of sleep a day, although they can get by with as little as six hours if they have to. Cats are particularly good at sleeping in small spaces, which allows them to make the best use of the nap times that occur throughout each day.
Birds, on the other hand, often only need around five hours of sleep at night but will take naps during the day—as many as 600 per year! This isn’t surprising considering birds spend most of their time eating and flying around looking for food; taking breaks helps them recharge their batteries.
Most other animals fall somewhere in between these two extremes. Elephants, for example, are similar to cats in that they can spend up to 14 hours sleeping each day but need less than half an hour at a time; while fish usually doze off after eating or when there’s nothing interesting happening in their environment–which is often–and don’t require much more than four hours total each day.
Do All Animals Rest?
It’s unknown if all animals need sleep, but it’s essential for most in order to function normally. The brain’s metabolism — or the chemical processes required to keep the body in order — depends on sleep to recharge. This process is relatively similar in all animals.
Without sleep, the brain begins to shut down. The longest recorded awake time for a human is 264 hours (about 11 days). Hallucinations, memory loss and mood swings are noted side effects of staying awake for long periods of time, but they’re all temporary. The individual who stayed awake for 11 days recovered after a couple days with normal sleep. The animal kingdom, so it seems, is the same way.
In the animal kingdom, sleep is more complex. Because most animals are at peak vulnerability when sleeping, it’s rarely seen as a luxury.
How Animals Sleep
Mammals sleep to save their energy and restore mental and physical energy. The amount of sleep a mammal needs depends on several factors, including age, body size, environment, diet, and the safety of its sleep site. Whether a mammal lives on land or in the sea can also affect how much sleep it needs.
Different mammals spend different amounts of time in non-REM sleep and REM sleep. However, all mammals studied thus far do exhibit signs of REM sleep, suggesting that mammals dream, just like humans do.
Mammalian sleep is often categorized as monophasic or polyphasic. Monophasic sleep describes animals who generally receive their sleep in one concentrated time period. Humans are an example of monophasic sleepers. Our circadian rhythms encourage us to sleep for extended periods at night and be active and alert during the day.
Polyphasic sleepers, on the other hand, tend to sleep in multiple periods throughout a 24-hour cycle. Polyphasic sleep is more common, as many animals need to maintain some level of vigilance against predators. However, if threats are minimized, animals can enjoy monophasic sleep. Marmosets, for example, sleep in trees surrounded by their family, enabling them to feel more protected and experience monophasic sleep.
Sleep is a mysterious and fascinating process, one that scientists have studied for years. We still don’t know exactly what happens while we sleep, but we do know that it helps our bodies and minds recharge.
We need sleep to survive, but the amount of sleep we need varies widely between animals—and even similarly classified species. For example, dolphins must be awake in order to breathe, so they only “sleep” with one half of their brain at a time.