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Animals That Sleep the Most

Australian Koala bears deserve the title of the animals that sleep the most in a day. These fluffy little gray-brown bears can sleep for 18 to 22 hours to preserve their energy for a good reason.

However, Koalas aren’t the only animals that love sleep. Several creatures in the animal kingdom cherish their sleep, and spend long hours snoozing more than the average human. Incredibly enough, some animals sleep less, while other animals seem to never sleep at all.

Here are some incredible sleep facts about some animals, including common pets.  

Sleep in Animals Explained

Sleep in animals describes the changes in their behavioral and psychological state of mind, such as reduced brain activity, responsiveness, and consciousness. In most animals, sleep rejuvenates their energy, helps in digestion, and replenishes glycogen levels in the brain.

Humans and animals have a 24-hour internal biological clock called the circadian rhythm that regulates sleep patterns. This clock makes nocturnal animals, such as cats, sleep during the day and stay awake during the night. Similarly, the clock influences nighttime sleeping and alertness in diurnal animals, such as humans, during the day.

However, animal sleep habits vary from one species to another.

The sleep cycle is divided into two categories: Random Eye Movement (REM) and Non-rapid Eye Movement (NREM) sleep stages. During sleep, many animals exhibit the characteristics of the REM sleep stage, which include:

  • homeostatic changes
  • slow brain activity
  • dreaming
  • muscle twitching
  • random eye movements

Scientists are still not sure whether or not all animals need sleep. Either way, there are many mind-blowing facts about how animals sleep that arouse curiosity in animal lovers.       

What Animals Sleep the Most?

From wild animals to domestic pets, here’s a list of animals known for spending long hours in slumberland.


Koalas sleep for too long in a day because of their diet. These marsupials feed on eucalyptus leaves that contain high toxin levels and low nutrients, requiring a lot of energy to digest. As a result, they spend 18 to 22 hours a day sleeping to conserve energy for digestion.

Little Brown Bats

Bats choose an unusual sleeping position — hanging upside down for close to 20 hours a day. Little brown bats are also nocturnal, or daytime sleepers. As a result, they have longer sleep cycles to preserve energy as koalas do.


Sloths make it to the list of animal sleepyheads, spending 20 hours of their slow and lazy day in slumberland. However, some studies show sloths living in the wild can sleep for fewer hours at night. These animals move slowly, and often hang off tree branches while going about their usual activities, including eating, mating, giving birth, and sleeping.

North American Opossum

Opossums are relatively slow animals that only move when necessary. Sometimes, they play dead when they feel threatened. Opossums sleep for about 18 to 20 hours a day, sparing only a few hours of the night looking for food.


Cats have a polyphasic sleep pattern, which involves sleeping in multiple intervals, rather than taking one long nap. These sleep intervals can range anywhere between 1 and 2 hours, accumulating to 12 to 18 hours a day. Animal experts suggest that about 40% of cats can sleep for more than 18 hours a day, with older cats sleeping more than younger ones.

Night Monkeys

Night monkeys have great night vision that keeps them active during the night. But, unfortunately, they don’t have the same kind of vision during the day. For this reason, they spend as long as 17 hours sleeping.


Pythons are among the laziest snakes, despite having incredible muscle strength and mass. They often hunt their prey at night, and after having their fill, they retreat into hiding. They can spend up to 18 hours sleeping, which helps them digest their food even better.

What Animals Sleep the Least?

Some animals are content with a few minutes of sleep per day, or no sleep at all, for a couple of days. In general, larger animals and grazers need less sleep than smaller carnivorous animals. Here are some famous animals that sleep for fewer hours.


Giraffes are hands down the tallest animals in the world, a title that comes at a cost.

Because of their height and body weight, they have difficulty getting off the ground, making them vulnerable to predators. As a result, these animals sleep standing for sleep cycles of 30 minutes or less at a time to stay safe.

Because they mostly sleep standing, they barely spend a total of 3 hours a day sleeping.


Deer are near the bottom of the food chain in the animal kingdom, making them an easy target for most predators. As a result, they are always worried about being attacked, causing them to forgo long hours of sleep to stay alert through the night. These animals sleep for about 3 to 4 hours a day, with the male heads of their herd opting for even fewer hours to stay alert.


Horses spend most of their day eating, and about four to five hours sleeping. They also sleep while standing, like giraffes, because they have difficulties getting up from the ground. Laying down for long periods also restricts blood flow around their body. However, these animals may lay down for about 30 minutes of their resting time to enjoy deep sleep in the REM sleep stage.


Elephants sleep for an average of two hours per day, and can do so while standing or laying down. Despite their ferocious appearance and enormous size, elephants are often at risk of being hunted by poachers and other predators. As a result, they can travel long distances looking for a safe place to live, even if it means being on the move all day without rest.

Migrating Birds

Migrating birds travel long distances searching for resources like food and nesting areas. These birds have a unique ability to sleep while flying in a phenomenon described as unihemispheric slow-wave sleep. In this state, one half of their brain sleeps while the other half remains awake, allowing them to keep flying with one eye open. As a result, they can cover long distances, and sleep for about an hour per day while flying.

When the birds finally get to their destinations, they compensate for the lost sleep with an average of a 13-hour long sleep.

Fun Animal Sleeping FAQs

Different animals have fascinating sleep cycles and behaviors that are interesting to learn. Here are some fun animal sleep facts you need to know.

Which Animals Hibernate?

Bears hibernate during winter to preserve energy, and reduce the need for food. During hibernation, bears become inactive, and have lower heart rates and body temperature. They hibernate for as long as eight months, especially in colder regions.

Other hibernating animals include bats, hedgehogs, and chipmunks.

Do Snakes Sleep?

Given that snakes have no eyelids, they appear awake all the time, even when they are resting. Snakes and other reptiles go into a state of brumation that resembles hibernation in bears. During this state, snakes eat less, have slower heart rates, and lower body temperature. Brumation also improves metabolism and digestion in reptiles.

Why do Snails Sleep so Long?

Some land snails can sleep up to three years in hibernation during winters. These creatures need moisture to survive, which explains why they hide under their shells, to avoid losing moisture.

However, snails have unique sleep patterns under ideal conditions. They can sleep for about 13 to 15 hours a day to boost their energy. Then, when they finally wake up, they can spend up to 30 hours without sleep.

How Long do Dogs Sleep?

Dogs can spend 10 to 12 hours of on and off sleep throughout the day and night. Interestingly, their sleeping positions can reveal a thing or two about their feelings.

For instance, if your dog sleeps on its sides, it means that it feels safe in that environment. On the other hand, if the dog curls up in a ball-like position, it may signify discomfort and insecurity. However, if the dog lays on its back, it means they have no reason to worry about protecting themselves from danger.

How do Meerkats Sleep?

Meerkats are diurnal, meaning they enjoy a full night’s sleep like humans. They snuggle on top of each other in large groups while inside their burrows to keep themselves warm and secure.

These creatures have a unique way of deciding how every member of the hierarchy sleeps. The pack’s leader sleeps beneath the heap while the guards sleep on the outer side to stay alert.

Do Fish Sleep?

Fish rest their bodies to relax and save energy, rather than falling into a deep sleep.

Interesting Animal Sleep Facts

Here are some interesting facts about animal sleep behaviors worth knowing.

  • Octopuses can change their color during the REM sleep stage
  • Reptiles are capable of dreaming during sleep
  • Guinea baboons sleep on treetops while on their heels to enable them to flee quickly in case of an attack
  • Given that dolphins depend on an active brain to breathe, they can only be half asleep when napping
  • Sea otters float on water while lying on their backs to catch some sleep. They wrap their paws and bodies with seaweeds, and sleep close to each other to avoid being carried away by water.
  • When sleeping, bullfrogs respond to external stimuli the same way they do when awake. As a result, some studies suggest that these amphibians don’t sleep at all.
  • Sperm whales sleep vertically, and close to the water surface. They also stay half awake, and spend only seven percent of their day sleeping.

Tips for Sleeping with Your Pet

If you wish to share your bed with your favorite pet, here are some tips to guide you.

  • Set boundaries between you and your pet to avoid attachment aggression
  • Keep the pets above the covers to prevent overheating, and transferring dirt into your bed
  • Ensure your pet is potty-trained before inviting them onto your bed
  • Use a mattress protector to protect your mattress from potty mishaps
  • Sleep on an allergen-resistant mattress to prevent microorganisms such as pet dander from living in your mattress.
  • Avoid sleeping with exotic pets such as pythons and iguanas to minimize chances of attacks

Some animals have certain human-like sleep characteristics. For example, research shows that dogs and mice can suffer from sleep disorders, such as sleep apnea, insomnia, and Restless Leg Syndrome. Other studies suggest that animals experience similar human sleep deprivation problems, such as sluggishness and mood swings.

Elizabeth Magill

Elizabeth Magill is a professional freelance writer and editor who holds an MBA. Liz specializes in writing about health news, medical conditions, healthy living, small business, career and work, personal finance, and green-living, including news and trending topics in these specialties. Her clients include Healthline, The Motley Fool, GoBanking Rates,, Big Interview, HealthNews, Intuit Small Business Blog, Intuit Health, American News Report,, IFX Medical, and many others. She’s also a published eBook author and ghost writer for various clients in the health, medical, career, small business, and personal finance niches.