Strange things about animal sleep

When migrating, the Swainson thrush stays awake all night and rests during the day. However, instead of prolonged naps, they fall asleep in bursts of just 9 seconds each time. Sometimes they only close one eye, the other eye and half of the brain are still active.

Monday, June 19, 2023

Humans spend almost a third of their lives sleeping. Sleep helps the nervous system rest, which is the time for the body to recover. With animals too, sleep is extremely important and more than that, it contains many strange things.

Winter sleep

Winter in the Arctic, the temperature drops very low, leading to very scarce food. When the ambient temperature drops, making it difficult to find food, polar bears begin to hibernate. Polar bears also have a layer of fat up to 10 cm thick to help keep the body warm, even when the temperature drops to -40 degrees Celsius. Polar bears are very insulators, if observed with infrared cameras, we can only see them. only their feet. Therefore, when the winter conditions are not favorable, or when the female bears are pregnant, they just crawl into the burrow, curl up and sleep to avoid the cold and save energy.

Their sleep is usually not deep. Heart rate decreased from 70 times to 8 times / minute, body temperature did not change. They can wake up immediately when needed. When in burrows, they do not eat and live off of their body fat; During this time, they do not defecate or urinate.

Many other animals are also forced to go to sleep in the winter because they can't run away, can't find food, or don't have thick fur to keep warm, they have to choose the form... sleep (just save energy). , hiding from predators and from the cold) like marmotte rats, or brown bears of the Pyrenees, they sleep for 6 months straight.

Hibernation is not only associated with cold, but sometimes a response to seasonal food shortages. Like the lemurs of Madagascar (despite living in the tropics, winter temperatures can be as high as 30 degrees Celsius), they still sleep during this period because they cannot find their favorite food. During sleep, their bodies live off of the fat stored in the tail (accounting for up to 40% of the body's fat stores). During 7 months of hibernation, their body temperature fluctuates from a few degrees to tens of degrees Celsius, depending on the outside environment. By regulating body temperature according to ambient temperature, lemurs are able to reduce metabolic rate and save energy, in a way similar to lizards and reptiles.

Weird sleeping patterns

Bats often hang upside down when they sleep. Perhaps bats are the only mammals that choose to sleep like that. Bats are the only animals that can fly; The hind legs are short and small, connected to the wing membranes, so it is difficult to move. So when they fall to the ground, they cannot stand up, nor walk. Therefore, bats are only suitable for climbing to a high place, hanging upside down, when in danger, just let go and spread their wings to fly.

Moreover, in winter, in the hanging upside down position, the bat will reduce direct contact with the cold cave ceiling, bury its head and body in the wing membrane, with thick mattress feathers on its body, which has the effect of preventing away from the cold outside air.

Birds can sleep standing right on a tree branch without falling to the ground. The secret lies in the tight ligament system in the bird's feet, which helps the foot firmly grasp the branch. In addition, because the brain of birds is more developed than that of reptiles, the cerebral hemispheres have not yet wrinkled, but have increased in size. The cerebellum is the most developed, the visual lobes are very large, making them able to balance very well even during sleep.

With migratory birds, they fly away continuously. Their flights are usually at night. Swainson's blackbirds have to fly about 3,000 miles from their habitat, breeding to warm sunny areas of South America, Canada and Alaska. When spring comes, they continue a journey from South America back to their homeland. When do they sleep?

Scientists have discovered that they stay awake all night and rest during the day. However, instead of long naps, they would sleep in several bursts, averaging 9 seconds each. This bird also sleeps in a few different ways. Sometimes they only close one eye, while the other eye and half of the brain are still active, helping them avoid lurking dangers. Sometimes they close both eyes, but only doze off.

This sleeping pattern is similar to that of the African giraffe. During "light sleep", the giraffe sleeps only part of its brain and its neck remains elevated. Only when sleeping deeply, giraffes put their head on the tail, but the time should not exceed 20 minutes. Because the giraffe is often attacked by a lion suddenly, it uses the secret of "sleeping while awake", combined with "sleep for a short time" to guard against predators. In doing so, they achieve their goal of being both safe and able to get proper rest.

Through studying animals' sleep, researchers found that when animals sleep, the brain can emit electromagnetic waves like the human brain, so animals can also dream. Some species dream a lot, for a long time, there are species that dream less, for a shorter time. For example, squirrels and bats dream frequently, birds dream relatively little, and reptiles almost never dream. This may involve them having to stay alert to the enemy at any time, in order to be able to escape in time.

Recently, scientists have discovered how dinosaurs slept. A fossil found in Liaoning (China) shows the dinosaur was in a sleeping position with its head curled up under its wings, like the sleep of modern birds. This is the first discovery of how dinosaurs slept.