Animals & Sleep
Animals are sleeping all around us. But it can be hard to see them. Sleep is a vulnerable time for most animals in the wild. They are unable to protect themselves while they are sleeping. This is why many animals prefer to sleep where they can remain hidden.
The reclusive nature of many sleeping animals makes it hard for scientists to observe them. Most studies have been performed in zoos. Few animals have been studied while sleeping in their natural environment. So there is still much for us to learn about sleeping animals.
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How do animals Sleep?
Many animals like cats and dogs simply lie down to sleep. But other animals have some unique and interesting sleep habits.
Some animals such as horses can “lock” their legs so that they can sleep while standing. This ability allows them to make a quick escape if a predator comes near. Some birds such as the flamingo can even sleep while balancing on only one leg!
Leopards also have excellent balance. These large cats can sleep on a tree limb without falling off. The three-toed sloth also sleeps on a tree limb. It tends to sleep in a sitting position, using a tree branch for back support.
Sea otters have a different kind of balance. They float on the surface of the water while sleeping. They often wrap themselves in kelp, which is a type of seaweed. The kelp prevents them from drifting away while they sleep.
The walrus also floats while it sleeps. But it bobs up and down in the water, sleeping in a vertical position. Instead of kelp, the walrus uses ice as an anchor. It digs its long tusks into the ice to stay in place while it sleeps.
Mallard ducks also sleep on the water. But they sleep in groups of four, floating in a row. The ducks on the ends of the row keep one eye open while they sleep. This allows them to watch for predators.
Marine mammals such as dolphins and whales have the ability to sleep with only one-half of their brain at a time. The other half of their brain remains awake so that they can swim while sleeping.
Tall giraffes twist around when they lie down to sleep. The giraffe curves its long neck around like a pretzel. Then it rests its head on its backside or on the ground.
These are just a few examples of the wide variety of animal sleep habits.
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Watch this video from Sea World and Busch Gardens to learn more:
How many hours do animals Sleep?
As this graph shows, animals have a wide range of daily sleep times. Some animals get their sleep by taking short naps. These brief naps might add up to only a few hours of sleep in a 24-hour day. Other animals snooze for hours at a time, sleeping for half the day or more.
A variety of factors affect how long an animal sleeps. Perhaps the most important factor is its size. In general, smaller animals need more sleep than larger animals. Small bats, chipmunks, and opossums all sleep for 15 hours or more per day. In contrast, big elephants, giraffes, and horses all sleep for about five hours or less.
Another factor is whether the animal is a hunter or is hunted. Predators such as lions and tigers get plenty of sleep; they have little to fear. But animals that are the prey, such as deer, tend to get less sleep. They need to remain alert and aware of nearby predators.
Age is another factor that affects the sleep of animals. Like humans, animals may sleep for different lengths of time at different life stages. For example, young animals may need to sleep more than adults.
Captivity also can affect an animal’s sleep. Wild animals often get more sleep when they are in a zoo. Food is provided for them, and they are safe from predators. So they can relax and sleep for longer periods of time.
In contrast, animals have to spend time hunting or gathering their food in the wild. Some animals have to migrate for weeks across long distances. Many also have to remain alert when predators are nearby. So they may spend less time sleeping in their natural environment.
For example, in captivity, the slow-moving sloth sleeps for about 16 hours per day. But a team of scientists went to the rainforest to study sloths. Results show that brown-throated, three-toed sloths slept for less than 10 hours per day in their natural environment.
Watch this video from National Geographic to learn more:
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