10 of the sleepiest animals in the world

The amount of sleep animals need depends on several factors, such as their age, body size, diet, whether they live on land or in water, and how safe their sleeping environment is. Some animals, like elephants, sleep as little as 2 hours a day. Others, like koalas, sloths, and little brown bats, can sleep for nearly the entire day. So, which animals are the sleepiest?

Which animals sleep the most?

Measuring how long animals actually sleep can be challenging. Researchers often estimate sleep duration based on periods of inactivity. However, this method is not always accurate, as some animals, like sloths and bats, may simply be resting, and their inactivity can be mistaken for sleep.

Despite these limitations, researchers have developed several ways to measure animal sleep. While not perfect, these methods help us understand which animals sleep the most and how their sleep behaviour varies.

Little brown bats

Bats, especially little brown bats, are known for sleeping a lot, sometimes up to 20 hours a day. Most bats are nocturnal, meaning they are active at night and sleep during the day. They usually leave their roosts at dusk to forage for insects until dawn, taking short breaks to rest and digest their food.

These tiny creatures use a lot of energy while flying around and can eat up to a third of their body weight in insects each night, so they need plenty of rest to recharge.

Since not many insects are around during cold weather, most bats hibernate in a safe, quiet place like a cave to survive the winter. They enter a deep sleep-like state called torpor, where their breathing slows down and their body temperature drops to conserve energy.

Koalas

Koalas might be cute and cuddly, but you might struggle to find them active during the day. They are mostly nocturnal and spend most of the day sleeping. Koalas sleep up to 18 to 20 hours a day. This is because their diet consists mainly of eucalyptus leaves, which are difficult to digest and low in nutrients. So, koalas rest a lot to conserve energy.

Tigers

Tigers are apex predators and need plenty of rest to conserve energy for hunting. They typically sleep between 18 and 20 hours a day. As nocturnal animals, tigers prefer to hunt at night, especially from dusk until midnight. Tigers often rest in secluded, shaded areas to stay cool during the day. They typically rest on rocks, in caves, in long grass, or near shallow water. 

North American opossums

The North American opossum is nocturnal and typically sleeps up to 18 hours a day. These highly adaptable creatures can thrive in habitats like open woodlands, swamps, and residential areas. During the day, they create sleeping dens inside tree trunks, logs, brush piles, or even beneath sheds and porches. However, they usually stay in one location for only a few days before moving on.

Opossums do not hibernate, as they need to remain active to forage for food. A common misconception is that opossums sleep while hanging from their tails. However, their tails are not strong enough to support their weight.

Giant armadillos

Giant armadillos usually sleep up to 18 hours a day. They are not particularly sociable and spend most of their time alone in burrows to rest and hide from predators. As nocturnal creatures, they are active at night to forage for food. Whilst giant armadillos do not hibernate, they tend to be less active during colder months and may spend more time in their burrows.

Pythons

If the thought of a slithering python seems terrifying, fear not; these reptiles can sleep for up to 18 hours, around 75% of their day. Most pythons are nocturnal, meaning they are mostly active at night and rest during the day. Interestingly, snakes do not have eyelids, so they cannot close their eyes when they sleep. This makes it tricky to tell if a python is actually asleep. However, there are signs that they may be sleeping, like no movement, no tongue-flicking, and slow, deep breathing.

Owl monkeys

Owl monkeys, also known as night monkeys, sleep for around 17 hours a day. They usually sleep in tree holes or dense foliage high above the ground to hide and protect themselves from predators. Owl monkeys are unique because they are the only species of monkeys that are active at night. Their large eyes and exceptional night vision help them survive and thrive in the dark.

Tree shrews

Tree shrews can spend up to 16 hours a day sleeping, which is around 66% of their day. These tiny mammals live in the tropical forests of South and South East Asia, and their sleep patterns are more similar to those of humans than rodents. They are mostly active during the day and sleep at night, although they may occasionally rest or nap during the day.

Sloths

While sloths are known for being slow and sluggish, they are also very sleepy. Sloths have a slow metabolism and, like koalas, they mostly eat leaves. They spend most of the day conserving energy and hiding from predators. Sloths sleep for around 15 hours a day and move slowly in and out of the shade to help regulate their body temperature.

Squirrels

While it is common to see squirrels active during the day as they forage for food like nuts, seeds, and fruits, they also sleep a lot. Squirrels can spend up to 15 hours a day sleeping, which is around 62% of the day. They mostly rest in dreys (nests built in trees), which they make from natural materials like twigs and leaves. 

Final thoughts

Sleep is essential for animals to conserve energy, recover, and survive. Their sleep patterns vary depending on their needs, environment, and lifestyle. While some animals get by on just a few hours, others sleep for nearly the entire day.

References 

• https://en.wikipedia.org/wiki/Sleep_in_animals.
• https://faculty.washington.edu/chudler/chasleep.html.
• https://www.ncbi.nlm.nih.gov/books/NBK11108/.