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Whether you have seen them in the wild or at the zoo, it is not uncommon to observe an animal sleeping. What might be puzzling for you is your first time seeing an animal sleeping while standing up. Some animals only sleep while standing up, while others get better sleep lying down but can also fit in a nap while standing. So, which animals sleep standing up?
Continue reading to learn about 20 animals that sleep standing up. Generally, animals that sleep standing up do so as a way to quickly escape danger if need be. Sleeping while standing is a way for animals to stay alert while resting, although they might sacrifice a higher quality, rapid eye movement (REM) sleep while lying down.
If you know anything about animals that sleep standing up, chances are that you are familiar with flamingos. Flamingos not only sleep while standing up, but they also only stand on one leg. Flamingos are able to sleep while standing on one leg due to a stay apparatus that essentially locks their leg into place and allows them to remain balanced.
A flamingo’s muscles can keep tense while allowing it to sleep. One of the main reasons flamingos have adapted to sleep standing on one leg is because most flamingos live on caustic salt flats, which have a very high level of toxicity. Though they are much better adapted to the area than humans and other animals, caustic salt flats can be harmful.
Judging by their size, it might surprise you to learn that elephants can also sleep while standing up. Most species of elephants do not need that many hours of sleep in a day, and may oftentimes go days without lying down to sleep. When they do lie down, however, they do so to achieve REM for better sleep.
If you have been to the zoo, you might have noticed an elephant standing very still. This does not always mean the elephant is asleep, but there is a way to tell. Studies suggest that if an elephant closes its eyes and lets its trunk go limp for more than five minutes, it is sleeping while standing up.
Crows are one of the many bird species that sleep standing up. Like more than half of all birds in the world, they belong to the order of Passeriformes, meaning that their legs have flexor tendons. These flexor tendons make sleeping while standing incredibly easy. Crows can sleep while standing up for much longer than many other animals, making their ability to do so useful for threatening environments.
Horses are another of the most common animals you might notice sleeping while standing up. Horses, like elephants, have a stay apparatus that allows one of their hind legs to lock in place and maintain balance while they sleep. Their front legs help out, but the single hind leg takes on most of the weight of the horse.
There is a main but ambiguous way to tell if a horse is sleeping while it is standing up. If the horse is standing still with its eyes closed and one of its hind legs is slightly bent, it may be sleeping. Since the other hind leg does most of the work, the bent hind leg gets to take a break for a while.
It might actually come as a surprise, but giraffes often sleep while lying down. However, because of their size, and particularly if there is a threat in their environment, giraffes can also sleep while standing up. If there is a predator in the area, the time it takes a sleeping giraffe that is lying down to stand up on its legs can be life-threatening.
Giraffes do not sleep for much of the day because they are such large herbivores. They spend much of their time eating food they can find. However, even if they are sleeping while standing up, you might be lucky enough to watch the towering animal slowly drop its legs, let its head fall to the side, and enter REM sleep while lying down.
Rhinos can sleep standing up, but chances are that you are not going to see a standing rhino that is asleep. Like many of the animals on this list, rhinos lie down to get a deeper sleep. In fact, rhinos are thought to appear quite adorable while sleeping lying down, as their legs tend to curl to the side, similar to a dog or cat.
Rhinos are one of the more versatile animals when it comes to sleeping. For instance, a busy day for a rhino could lead to a short nap while standing under the shade of a tree. On the other hand, if a rhino can find its way into a mud bath, you might find it catching a power nap while relaxing.
Songbirds, like crows, are Passeriformes, so their flexor tendon allows them to sleep while standing up. Although most songbirds have extremely skinny legs, the flexor tendon allows them to grab hold tightly of a branch to prevent themselves from moving around while they sleep. Sleeping while standing is a major advantage for birds who have to avoid danger, including apex predators.
Cranes are large birds that often sleep while standing up. Like flamingos, you might observe a crane sleeping on one leg. However, they can also sleep while standing on both legs. Neither is more common than the other.
It can be difficult to tell if a crane is sleeping while it is standing. Oftentimes, cranes keep still if they sense something in their area. They may remain still for minutes. One major way to tell if a crane is sleeping while standing is if it curls and tucks its head into its body. However, cranes can also sleep with their necks elongated and their heads slightly drooped, so it is not always easy to confirm.
Like other large animals that sleep standing up, one of the reasons camels sleep standing up is to avoid the struggle of climbing to a standing position in the face of danger. Camels also need to sleep lying down for REM sleep, but sleeping while standing can be important.
It takes an animal such as a camel quite a long time to digest cellulose. If they are lying down, their stomach might not be in a position to process the cellulose quickly and efficiently. Sleeping while standing up allows the digestion process to be achieved more smoothly, which can prevent internal problems for a camel.
The same rules for large animals attaining REM sleep apply to moose, but you can find a moose sleeping while standing up. How they sleep standing up is quite interesting. When a moose remains standing to sleep, it falls into a semi-conscious state. Its head and neck relax, and it will likely crane them downwards.
A standing moose is not a green light for predators. Moose have a keen sense of hearing, and while they may doze off while standing, their ears are always alert. In fact, that might hone in their hearing even more impressively while they sleep standing up. It is also worth mentioning that moose can look goofy when they sleep lying down. They might typically tuck their legs under them, but you may also see them with all four of their legs stretched out.
Ducks are another animal whose sleep habits are versatile. They can sleep while balled up on the ground, or you might even see them asleep on top of the water. However, ducks often fit some rest in while standing up. Like flamingos and cranes, they may sleep on only one leg.
Ducks that sleep while standing on one leg might typically be found in colder climates. The reason they sleep on one leg is to prevent the other leg from losing too much body heat. Because ducks’ legs are not very thick, they can lose a lot of body heat if they do not cover their legs. Tucking one leg into their body allows them to preserve as much heat as possible.
When it comes to geese, things get interesting. Technically, a goose is too top-heavy to be able to sleep while standing on one leg like many other birds. However, geese can balance on one leg for quite some time to regulate their temperature.
Geese do not typically sleep while standing up, but it is not unheard of. However, if you see a goose apparently sleeping while standing on both legs, it is far from a deep sleep. Geese can stand on two legs and fall into unihemispheric sleep, which means they are in a state of rest while maintaining full consciousness.
Deer can sleep standing up. If they are sleeping while lying down, it likely means that they are in an area that they believe to be safe and secure. When they are comfortable enough, deer sleep lying down. However, there are many threats to a deer’s livelihood.
Deer sleep while standing up when they are cautious of the area they are in. Particularly, if they have had a recent scare but need to rest, they will sleep while standing up to be able to flee in the event of an attack. One of the neatest facts concerning this list is that some deer can actually sleep with their eyes open while standing up.
Cows rarely sleep while standing up, but they can. Cows will not get high-quality sleep while standing, but they can get some decent rest. Like camels, standing can be better for a cow’s digestion, but the same effect can be achieved while they are grazing a field.
It is important for cows to sleep lying down because it promotes healthy udders. When a cow sleeps while standing up, its udders may not get proper blood circulation. Lying down in a comfortable position allows a cow’s udders to circulate blood and aid in milk production.
Wildebeest can also be found sleeping while standing, but they get better sleep while lying down. However, some of the strongest and fastest animals in the world - lions and cheetahs - are one of the wildebeest’s main predators, so sleeping while standing may be the only option in some cases. Having to scramble to their feet while running from danger can be detrimental for wildebeest.
Reindeer can get a good amount of rest standing up, but, like deer, they do not sleep much of the day, so they may prefer to get a deeper sleep while lying down. Still, reindeer have numerous predators, so they must always be wary of their sleeping arrangements.
Reindeer also tend to live in extremely cold climates, so lying down to sleep can be a much better option for both comfort and health. However, they are careful of where they choose to sleep. With several threats in the area, you may not find a reindeer sleeping while lying down.
Gazelles can sleep standing up, and for them, it makes sense. Most gazelles hardly sleep for more than an hour a day. Actually, they sleep in short, five-minute bursts that only add up to an hour. So, while they might be resting regularly, they are always alert to their surroundings.
Storks are much like flamingos in that they can sleep while standing on only one leg. However, when the temperature rises, you might find a stork sleeping while standing on both of its legs. With one leg tucked into its body, a stork may retain too much heat. As a result, it may lower the leg to be more comfortable.
Zebras, like many other prey animals, have developed the ability to sleep while standing up. They do occasionally lie down, but they can rest while standing up. Their joints can lock, preventing them from falling over while they sleep standing up. Zebras are another species that have a variety of predators, so it is important for them to be alert as often as possible.
Unlike many of the other animals listed, donkeys are typically more comfortable sleeping while standing up. It is not uncommon to observe a donkey lying down during the day, but in most cases, this is just to rest or relax. Donkeys prefer to sleep standing up because it keeps them aware of their surroundings.
Donkeys possess a unique attribute in their brain that allows them to maintain balance when they sleep standing up. Even with joints that lock, other animals might not get as high of a quality of sleep while standing that a donkey does.
As you have seen from this list, many animals can sleep while standing up but get a better quality of sleep while lying down. So, which animals only sleep standing up?
It is not so simple to list animals that solely sleep standing up, but there are a few that are rarely found sleeping while lying down. Flamingos, donkeys, giraffes, and - excluding ducks and geese - the other birds listed above all sleep standing up the majority of the time.
Many animals sleep while standing up. Most of the time, the reason for doing so involves staying alert in their surroundings. However, several animals that might lightly nap while standing up can only get high-quality sleep while lying down.
