Ah, a dream, the envy of those who cannot receive it, and a generous reward for those who can. When we think about sleep, we usually imagine a luxurious bed, soothing music, and comfy pillows that help us drift into horizontal sleep. You may be surprised to learn that there are many species in the animal kingdom that often sleep while standing! Apart from astronauts in zero gravity cots attached to the walls, not many people can say the same. So today, let’s take a look at how you can sleep while standing, take a look at 17 animals that can sleep while standing, and explore some of the reasons why they have adapted to this.
How do animals sleep while standing?
To sleep while standing, all of the animals listed below have developed unique adaptations. Details vary from species to species, but usually include one or more of the following: an anchor, gravity manipulation, or a flexor tendon. Let’s take a quick look at what these adaptations are and how they work.
Stay apparatus
The fixation apparatus is a set of muscles, ligaments and tendons that fix the limbs of a large herbivore in place, allowing it to “remain” in a standing position. By blocking the main joints, the herbivore can relax the rest of the muscles and enter into light sleep. This apparatus is typical for quite a few species.
Gravity manipulation
Gravity is a powerful force, and fighting it takes a lot of energy. Several species of birds have managed to find a loophole by strategically using gravity while they sleep. These birds sleep on one leg just below their center of mass, which alters their balance and localizes gravitational pressure. Localized downward pressure fixes their ankles, keeping them upright. Simply put, these birds created a pressure lock using gravitational forces.
Tendon flexors
Many other birds can also sleep while standing using what is called the flexor tendon. There are usually two flexor tendons that run down from the back of the bird’s legs to the toes and contract as they land on the perch. This is an involuntary reflex. The tendons relax when the bird extends its legs, but while the bird is stationary, the tendons contract, providing sufficient rigidity for the bird to fall asleep while standing.
Animals that can sleep while standing
According to numerous testimonies and observations, the following five animals can sleep while standing and do it regularly. See if any of the titles surprise you!
Horses
Horses are perhaps the most well-known animal species that use resting devices, allowing them to fall asleep with light, vertical sleep. This does not mean that the horse sleeps like this all night. During NREM sleep and REM sleep (rapid eye movement), the horse must lie down because its muscles, joints, tendons and ligaments will be in a state of weakness (atony) that no support can support. Thus, the sleeper device is used more as a means of getting light sleep than as a mechanism for getting a full night’s sleep.
Elephants
Elephants have a peculiar dream. Those in captivity usually sleep four to six hours a day, while those observed in the wild can only sleep two hours a day. Domesticated elephants tend to sleep more while lying down, while wild elephants tend to sleep standing up. The difference is likely due to the long and tedious awakening process from a horizontal position, which makes the elephant vulnerable to threats in the wild. Domesticated elephants don’t really cope with many life / death situations, so the need for standing up sleep is reduced.
Giraffes
Giraffes, like elephants, require very little sleep. A typical adult giraffe sleeps one to two hours a day on average, but never in one cycle. In fact, the average giraffe’s sleep lasts between two and ten minutes! With such a fast cycle, it makes sense that giraffes would benefit from the ability to sleep while standing. Lying down to the tallest living animal in the world to get up again in ten minutes is a tremendous waste of energy. Since predation is a problem in the savannah where they live, their cycles of constant sleep give them the best chance to wake up quickly and escape from a pursuing predator.
Flamingo
Masters of gravity manipulation strategy, flamingos can sleep and stand for extended periods of time on only one leg, which requires much less muscle activity than standing on two legs. When their body rests on one leg, the weight of the flamingo forces the ankle of the outstretched leg (located where you think the knee might be) lock into position. Researchers in 2017 confirmed this by conducting a series of experiments on both living and recently deceased flamingos. Perhaps the most shocking discovery was that researchers were able to activate the locking mechanism of recently deceased flamingos and make them stand still without falling, which is crazy!
Crows (Passerines)
Ravens are adorable creatures; they have memories, they understand causality on a par with a seven-year-old, learn from their environment, and may even harbor resentment! Because they belong to the order of passerines (which includes more than half of the world’s birds), crows also have flexor tendons. Flexor tendons allow crows to sleep while standing longer than horses, elephants, and giraffes. In addition to crows, other common birds such as pigeons, quails and canaries belong to this order.
Why do animals sleep while standing?
There are several reasons why an animal prefers to sleep while standing. Perhaps the most serious of these will be the threat of predation. The process of waking up from horizontal sleep takes a long time and leaves the predators the opportunity to take advantage of weak prey. By sleeping while standing, herbivores give themselves the best chance of survival.
Giraffes and horses also have a clear digestive benefit. Digestion in large herbivores is time-consuming and laborious. Sleeping while standing allows the digestive process to continue while the animal is resting.
For some animals, less effort is key. The flamingo’s gravity manipulation allows it to use as little energy as possible. Efficiency promotes adaptation, and in the case of flamingos, it is easiest to sleep standing on one leg. Another reason flamingos may have adapted to sleeping while standing is their surroundings. Birds live mainly in caustic salt marshes, which are poisonous. The flamingos’ long legs allow their vital organs to remain suspended above the ground in a much safer place than lying down.
Can people sleep while standing?
Unfortunately, we do not have any fixing devices or the ability to move in such a way as to minimize the gravitational forces acting on us. This does not mean that you cannot fall asleep while standing, but if you do, any external force or muscle relaxation will cause your body to tumble to the ground. Save the experiment and sleep in a comfortable bed.
List of 17 animals that can sleep while standing
In addition to the five above, many other animals have the ability to sleep while standing. Here are 17 examples of animals that sleep while standing:
- Camels
- Cranes
- Cows
- Deer
- Donkeys
- Ducks
- Gazelles
- Geese
- Songbirds
- Storks
- Rhinos
- Zebras
- Horses
- Elephants
- Giraffes
- Flamingo
- Crows