These animals get creative to sleep


Pet owners know the difficulties of trying to sleep with an animal in the house. Nocturnal pets can be particularly frustrating: Upon awakening, a cat may try to choke you to death or bite your nose. Meanwhile, rabbits are crepuscular, which means they are active at dawn and dusk. So people are probably used to their rabbits wreaking havoc in the wee hours of the morning.

But these are far from the weirdest sleeping habits in the animal kingdom. Although you might assume that all animals sleep the same way, researchers have observed a wide variety states of rest. Here are some strange strategies that animals have developed to rest:

Half-brain sleep

For those who live in nature, it can be hard to close your eyes. On the one hand, it is necessary to dodge predators. And since some birds fly over oceans and cannot land for months at a time, they also face quite a challenge. Ditto for dolphins or whales, which aim not to drown instantly.

Aquatic birds and mammals have adopted an interesting strategy to overcome these obstacles: they induce drowsiness in only one half of the brain, a behavior called unihemispheric sleep. This allows the great frigate continue to hover while he sleeps, and dolphins, whales and other cetaceans surface regularly to breathe. Other marine mammals, including seals and walruses, also use this technique to catch a few winks underwater. Birds and seals can mix it up, switching back and forth between regular and unihemispheric sleep, but cetaceans can only sleep unihemispherically. Sperm whales also have their own weird twist on sleeping habits – they sleep verticallysuspended strangely in the water.

sleep on the move

Underwater animals have developed other unique ways of sleeping under the waves. But the sharks encountered roadblocks. Sharks descend from a old line (older than grass, flowering plants and the rings of Saturn) and have survived multiple mass extinctions, but some species have a rather surprising problem with life underwater: they cannot breathe less swimming.

All fish need water to flow over their gills in order to extract oxygen from them, and some have specialized muscles that pull water over their gills so they can catch a few winks without drowning. However, sharks do not always have this advantage. This is one of the reasons why shark finning is so cruel, since a shark that cannot swim will inevitably drown.

But even without human intervention, sharks would still encounter this problem. It was even once thought that sharks simply didn’t sleep, although recent research has reversed that idea.

For some sharks, it turns out that their swimming is governed by their spinal cord, not their brain. When they doze off, the spinal cord supports their movement and allows them to keep moving, albeit more slowly. Some great whites have been documented do something amazing: They swim slowly and face a current, presumably making breathing easier.

Avoid bedtime

In a dangerous world, falling asleep can be risky. Land animals approach this dilemma in different ways. For example, ducks sleep in rowsthe outer limbs keeping their eyes open to the outside (they rely on unihemispheric sleep to achieve this).

Larger animals, especially four-legged ones, supplement time spent sleeping on the floor with standing naps. Horses have ligaments in their legs that lock together, so they can take a short rest without falling. However, they need to lie down to sleep well. Giraffes and elephants are also known to rest on their feet a bit.

Killer whales and dolphins take things to the next level. Few animals are more at risk than newborns, and if the mother sticks around, she must protect that baby from predators. As a result, neither mother nor baby catch all the winks up to a month. This contradicts the behavior of all other types of mammals, which typically sleep the most right after birth and gradually accumulate less over time.

Hibernate all night

Perhaps the most famous hibernators, bears spend their winters in a deep sleep that lowers their body temperature and slows their metabolism. Many other animals, including snakes (technically called brumation in their case), squirrels and hedgehogs do the same. Hibernation is an example of heterothermyin which mammals or birds that generally have stable body temperatures change them under specific conditions.

But in another type of heterothermy, animals perform hibernation-like activity at night or even during the day. Hummingbirds use it as an adaptation strategy to manage their high-speed lifestyle, especially in cold conditions. These birds spend the night in a state called torpor, a rest so deep that it is often mistaken for death. Some hummingbirds seem able to adjust their torpor according to local conditions.

In this process, their metabolism slows down and their body temperature drops to 3.26 degrees Celsius, the lowest figure ever for any non-hibernating bird or mammal. This gives them enough time to sleep through the night, wake up shivering in the morning, and go back to binge eating.

Nothing but REM

The platypus is legendary for its strange appearance. In fact, it’s so strange that reports from British settlers of the supposed beaver-duck hybrid have been dismissed as a hoax. The platypus actually belongs to an ancient line of egg-laying mammals called monotremes. He has a poisonous ankle spur and uses electroreception to hunt. The sleeping habits of this seemingly mythical creature are also very unusual. They usually sleep between six and eight hours a night. Of these, between 5.8 and eight hours is REM sleep. In mammals, REM is a critical phase of sleep, but it typically lasts less than half the duration of a total siesta.

Overall, the platypus gets more REM sleep than any other animal. Their unique place on the evolutionary tree as one of only two living representatives of the order Monotreme (besides the echidnas) might even offer insight into the lifestyles of our long-dead ancestors.

Indeed, in some respects, monotremes resemble pre-mammalian reptiles more than their mammalian counterparts (laying eggs, lack of nipples, etc.). Research on how echidnas sleep suggested that they undergo a similar process, where the distinction between REM and non-REM sleep is at least blurred, if not non-existent. This suggests that earlier mammals may have had much more REM sleep than modern ones – and that REM can even be traced back to pre-mammalian reptiles.


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