Many people think that animals sleep just like people. But this is not so.
Some animals generally never fully sleep, but otherwise give their brain a rest. And insects, for example, simply fall into a kind of numbness.
Even human sleep for us is still a very mysterious phenomenon, and even the sleep of animals has hardly been studied at all (Good news about animals – goodnewsanimal.ru).
10. How do monkeys sleep
Humanoid signs, such as gorillas, orangutans and chimpanzees, really sleep almost like us. At night, they arrange for themselves something like a bed of leaves, grass or twigs and curl up in these "nests" like people in a warm bed.
Small primates, like monkeys or macaques, sleep differently, they simply freeze while sitting on a branch in a more comfortable position, move in a dream and wake up from time to time to check if there are predators nearby.
9. Elephants and giraffes sleep standing
Large hoofed animals like elephants and giraffes most often simply cannot find a reliable shelter for sleeping, therefore they are forced to sleep standing up, always being ready to jump in and run away from danger.
These animals have special muscle "locks" in the knee area so that they do not have to strain their muscles in a dream. These "locks" automatically make the legs stand upright when the animal falls asleep. The same mechanism of sleep is in horses, cows and even birds.
But even with such a mechanism, these animals still need to regularly lie down on the ground in order to sleep normally. The fact is that while standing up, they cannot enter the so-called REM sleep phase (REM phase), which is very important for well-being. It is in this phase that a person sees vivid dreams.
For normal health, an elephant needs to sleep in the REM sleep phase at least once in 3-4 days. Moreover, he only needs 30 minutes of such a dream for. The giraffe, on the other hand, sleeps only 30 minutes and for the norm he needs to sleep in the REM sleep phase only 5 minutes.
8. Dolphins sleep with one eye open
Like other cetacean dolphins, I can’t sleep in the usual sense of the word. Most marine mammals must constantly beware of predators, and in addition they need to float to the surface in order to breathe.
If a dolphin falls asleep as a person, he will simply drown. In addition, dolphins are warm-blooded creatures that most often live in cool waters, so they need to constantly move so that their body temperature does not drop.
Therefore, evolution has come up with a special dream for dolphins when only half of the brain falls asleep. Scientists call such a dream the Unipolispherical slow sleep and it is characteristic not only for cetaceans, but also for many migratory bird species.
7. Newborn killer whales never sleep
Adult killer whales sleep about 5-8 hours a day, however, young killer whales and their mothers do not sleep at all for 3-4 weeks after giving birth. And this is also characteristic of other females and young cetaceans.
Basically, this is a protective mechanism against predators, for which the cub is a tasty prey, but there are other reasons. The small calf is still too weak and slowly swimming, in addition, he still does not have subcutaneous fat to stay afloat. To survive, he must constantly move next to his mother, staying in her stream.
Moreover, this is so important that the killer whales even abandoned the Unipolispherical slow sleep, preferring him to be fully awake for a month, until the baby is a little older.
6. Ducks put up "sentinels"
Wild ducks have an interesting sleep mechanism when they are in a pack. At night, those ducks that are at the edges of the group sleep in the crawl with the same mechanism that we wrote about above. And the ducks that are inside the group sleep in normal full sleep.
This sentinel tactic works great when you have to watch out for predators, but it’s also vital that most of the pack have a good rest. Whether the "sentinel" ducks change the next night with other ducks, while scientists do not know.
5. Migratory birds can sleep on the fly
Scientists have not yet precisely studied the mechanism by which migratory birds do not fall on the ground for the night, but continue to fly for several weeks. According to their assumption, these birds just learned to sleep in the air.
A couple of years ago, scientists from the Max Planck Institute studied how frigates birds sleep. It turned out that on earth they can sleep 12 hours a day, but then they can fly for weeks in the sky over the ocean in search of fish and not returning to the earth.
Scientists have found that frigates can really sleep on the fly, and they do this very quickly, no more than a few minutes at a time. They can also sleep with just one eye.
4. Reptiles can also dream
Until recently, scientists believed that only mammals and birds can enter the phase of REM sleep and thus can dream. This really puzzled many, because the birds came from reptiles, why can’t reptiles dream?
It turned out that all the same they can. Researcher Gilles Laurent from the Max Planck Institute (Germany) connected an electroencephalogram (EEG) to the lizards of the species, and soon noticed some very familiar sleep cycles on the chart.
It turned out that during a day, bearded dragons can enter the REM sleep phase up to 350 times, which at the same time lasts no more than 80 seconds. In humans, for example, in a 90-minute sleep, the REM sleep phase lasts 4-5 minutes.
3. Fish sleep in the dark
Researcher Emmanuel Migno of Stanford University and his colleagues studied how fish sleep on the example of Danio rerio aquarium fish. They tried to find out if the fish could suffer from insomnia or lack of sleep, but they saw that the fish use a circadian rhythm.
When lamps are lit near the aquarium, the fish do not sleep at all, and when you leave the aquarium in the dark, the fish fall asleep. The fact is that light releases certain hormones that determine the need for sleep.
Not all fish, however, use the circadian rhythm, the eyeless Mexican cave fish lives in constant darkness and therefore the circadian rhythm does not affect it in any way.
2. Parrot fish in a dream secrete a huge amount of mucus
The so-called parrot fish feed mainly on coral polyps, and when they fall asleep at night, they intensify the production of mucus, which covers their entire body.
Scientists have been arguing for a long time about why this function is needed, someone says that this is how parrot fish are protected from predators, someone that is a kind of protection from sunlight. According to Alexandra Gratter of the University of Queensland, similarly, parrot fish escape from isopod crustaceans, which are scavengers and active predators.
1. Walruses cling tusks to ice
Walruses can easily stay awake for up to 84 hours in a row, and then fully compensate for this damage. On land, walrus sleeps on average up to 19 hours a day. In water, walruses have certain sleep problems, they have to sleep in short passages and regularly float to the surface for breathing.
But some walruses found an elegant way out – they stick their heads out of the water and plunge their large tusks deeper into the ice edge. And after that they calmly fall asleep. The body of the walrus is in the water, and the head is outside.
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