Scientists still do not have an exact answer to this question, although they offer a lot of various hypotheses. For example, some of them argue that thanks to dreams, humanity was able to survive in primitive times, honing for millions of years at night, in a dream, different ways to cope with the threats that the surrounding world was full of.
Dreams have been investigated since 1953. Then Eugene Azerinsky, an emigrant from the USSR, recorded the rapid movements of a person's eyes during sleep. Research Azerinsky, on the advice of the then famous physiologist Nathaniel Kleitman, carried out, observing his sleeping child with a polygraph. It was then that he found out that an hour after falling asleep, the child's eyes begin to move quickly under the eyelids. After a while, these movements disappeared, and after an hour and a half they resumed again.
Of course, they tried to study dreams before, even before our era. For example, Aristotle has a book called Explanation of Dreams. However, everyone who has dealt with this issue has always thought that during sleep, the brain also falls asleep and no activity occurs.
Thanks to research, today we know that the son consists of two phases - slow sleep and fast sleep, in total, it takes 90 minutes. These phases are repeated 3-4 times during the night. Internecine sleep, in turn, also has several stages - drowsiness, sleep spindles and two stages of deep sleep. during this period we also see dreams, but images are not created in them, it is as if you are thinking about something.
But we see real dreams during REM sleep - each of them takes only 10-15 minutes. As scientists have found out, during this period, the part of the brain leading to the spinal cord, which is responsible for movement, is blocked. Thus, the flow of nerve impulses to the muscles is interrupted, and all human movements are blocked, except for the eyes and breathing. Otherwise, we would run in our sleep. Or they did whatever we dream about. This phase of sleep is also called paradoxical - because the brain is awake at this time in the same way as in the daytime. In this case, the person is deeply asleep. Usually we manage to see from four to six dreams per night during the night, but more often than not we do not remember them.
What are dreams for? It is generally accepted that dreams are an evolutionary property of man. They process and translate information from short-term memory to long-term memory. For example, if a schoolchild or student learned something before the exam, then slept for six to eight hours, then knowledge is assimilated and reproduced more easily and better. Roughly speaking, this is the consolidation of memory. After all, all the information that was received during the day, the brain does not have time to process. Therefore, he does it at night.
Do animals dream? Until recently, physiologists gave a negative answer to this question. But after all, everyone who has dma animals knows well how in a dream their pets move their paws, make sounds, seem to run somewhere.
And scientists decided to find experimental evidence that animals also dream. To do this, they conducted an experiment on rats, with which they inserted electrodes into the brain structures and registered neurons responsible for orientation in space (such are found in all mammals). Then we put the rats in a maze and looked at which neurons work when the rat runs to the right, which ones when to the left. And when scientists began to register the activity of these neurons in sleeping rats, this served as evidence that the rat outside saw the trajectory of its movement. She seemed to be repeating a maze run in another reality. Two years ago, scientists received the Nobel Prize for this experiment.
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But fish, reptiles and amphibians do not sleep, like mammals. They have periods similar to sleep. And what's most surprising is that they don't have REM sleep. We got our dreams with warm-bloodedness.