The koala holds the accolade for 'the animal that sleeps the most'. This Australian icon sleeps for 20-22 hours each day (sounds good to us), making it the sleepiest creature in the animal kingdom.
Koalas. Hats off to the (somewhat disputed) king of sleep: the Koala bear. They've been reported to sleep up to 22 hours a day in captivity, over 90% of their lives.
Some animals, like koalas, sleep a lot — up to 22 hours a day. Cats sleep for about 15 hours a day. Worker ants average almost five hours of sleep a day, but it's in the form of around 250 one-minute power naps.
Cats and dogs have a sleeping cycle of 12 hours a day. The sleeping time can be a specific period or time interval. It differs from one animal to another.
Snails need moisture to survive; so if the weather is not cooperating, they can actually sleep up to three years. It has been reported that depending on geography, snails can shift into hibernation (which occurs in the winter), or estivation (also known as 'summer sleep'), helping to escape warm climates.
Bullfrogs… No rest for the Bullfrog. The bullfrog was chosen as an animal that doesn't sleep because when tested for responsiveness by being shocked, it had the same reaction whether awake or resting.
Giraffes are known as the mammal that sleeps the least. Despite being the tallest and weighing up to 3,000, they reportedly only need 30 minutes of shut-eye per day. According to a study from 1996, that refers to deep sleep with their total time spent sleeping being closer to 4.5 hours.
They react differently when external stimuli are applied while sleeping and while awake. But the bullfrog, Lithobates catesbeianus show the same reaction in both situations. This indicates that bullfrogs do not sleep. Lithobates catesbeianus is an animal that cannot sleep.
Lions wake up early in the morning to go hunting for their food, as these wild beasts are at the top of the food chain. This metaphor is representative of those of you who are morning risers, who love to get up early and attack the day with lots of optimism and drive.
In the case of the elephant, in fact, it's impossible. Unlike most mammals, the bones in elephant legs are all pointed downwards, which means they don't have the "spring" required to push off the ground.
Horses, zebras and elephants are just 3 examples of animals that can sleep standing up, because it allows them to quickly escape an attack by a predator (the process of standing up can be slow and clumsy).
Koalas. Koalas are not only extremely cute, they're smart, too! The marsupials know how to listen to their bodies and can dive into a deep sleep for an average of 22 hours a day. Koalas snack on eucalyptus leaves, which aren't high in nutrients—the abundant rest makes this diet possible.
The American Pygmy Shrew (Sorex hoyi)
Every day it eats three times its own weight. To do so it needs to constantly eat and never sleeps for more than a few minutes. An hour without food would mean certain death.
Because horses are big animals, their blood flow can be restricted by laying down for long periods of time. This causes excess pressure on their internal organs, which is why they only lay down for REM sleep.
According to research, while trees may not sleep in the same way animals do, they do relax their branches during nighttime, which suggests that yes, trees have activity-rest cycles. These cycles can also vary depending on the tree species.
Can You Sleep Standing Up? Sleeping while standing is even more difficult for humans than sleeping sitting up due to the loss of muscle tone that occurs during REM sleep. However, this practice has been observed in certain situations, such as soldiers on nighttime sentry duty.
Walruses are pretty lucky in that they can literally sleep anywhere both in the water and on land. Some walruses have even been observed resting in water while using their tusks to hang from the ice. When on land they can fall into a deep sleep lasting up to 19 hours.
Regardless of their preferred mode, bats, elephants, frogs, honeybees, humans and more have something in common: They all sleep. In fact, scientists have yet to find a truly sleepless creature.
Dolphins. As weird as it sounds, but it's true, newborn dolphins don't sleep for a month. Scientists found that even the mother stays awake during this time. Dolphins can stay alert with at least one eye open at all times.
The new research shows that dolphins have the longest memory yet known in any species other than people.
There are a number of marine species that outlive humans, and the mammal species that holds the record for longevity is the bowhead whale, which can live for 200 years - or more.
Crocodiles sleep with one eye open and half their brain awake.