Sleep and dreams
What is interesting is the fact that dreams that seem to be rich in content and seem to take a long time to sleep actually flow very quickly - just a few seconds. The idea of time and space in a dream is dramatically disturbed. Such a case, for example, is described. One famous playwright, having appeared at the performance of his play, fell asleep with fatigue and malaise. In a dream, he saw his entire play from beginning to end, followed the development of the action and how his work is accepted by the public.
Finally, the curtain falls under the deafening applause, the playwright wakes up and, to his surprise, he hears that only the first replicas of the first scene are pronounced on the stage. All the peripetias of the play, which have passed in front of his eyes during his sleep, thus took only a few seconds.
The fact that even in a vigilant state of performance and memories can sometimes rush with unusual speed, testify to the testimony of people who have survived the moment of mortal danger. At such a moment, the memories of almost the entire life will allegedly interfere.
No less frequent source of dreams are excitations that come to the brain not from the outside world, but from the internal organs of the body - stomach, intestine, bladder, lungs, heart, etc. All these organs are sensitive and connected by nervous pathways with the "organ of the psyche" - the cortex of the large hemispheres of the brain. During the day we usually do not notice the "signals" that come from the internal organs, because consciousness is filled with stronger impressions of the outside world.
At night, the situation changes: the more the activity of the external senses stops, the more clearly irritations arising in the internal organs begin to feel - especially these irritations are caused by some - or painful processes. So there are painful, nightmare dreams, frightening superstitious people. Disorder during sleep normal heart activity or breathing - the most frequent source of such dreams.
Dreams caused by internal irritation can have diagnostic significance. They can sometimes be used by an experienced physician to detect the onset of an internal disease that is still in a wakeful state and does not show up with the symptoms that are typical of it.
Dreams are partial activities of the depressed cerebral cortex during sleep, caused by various irritations of the external or internal senses. This is the meaning of Dr. Ox's above statements, expressed a hundred years ago, but already approaching the modern teaching of sleep and dreams, experimentally justified by Pavlov and his staff.
Ox was wrong only in understanding the reasons that lead to the oppression of brain cells during the time. He (like almost all of his contemporaries) believed that such a reason was the self-poisoning of brain cells by metabolic products - "sleep poisons". which accumulate in the blood and cells while awake and act in a sleepy manner, like drugs.
In fact, we fall asleep before poisonous metabolism products have even accumulated. We can take a sweet nap even in the morning, after a long enough night's sleep, when "sleep poisons" are out of the question. And only in exceptional cases, when vigilance, supported by artificial methods, lasts for several days in a row, when the need for sleep becomes painful, insurmountable, - only then the factor of self-poisoning begins to play a major role.
This is evidenced by the interesting observations of Moscow professor P. K. Anokhin, made in 1939 at a rare site - two conjoined human twins. These twins had a common torso, one heart and a common circulatory system, but two heads, two brains. And it was not uncommon for one head to fall asleep while the other kept awake. So, not the humoral factor (blood composition) plays a major role in falling asleep. After all, in this case, both brains, receiving the same blood composition, could be in different functional states: one brain in a state of oppression, the other waking up.
What is the beneficent factor that makes us fall asleep in time and thus protects our brain from fatigue, from the danger of self-possession? Pavlov's classical experiments, using the method of formation of conditional reflexes, proved that the factor causing sleep is the inhibition of nerve cells that make up the cerebral hemisphere cortex.
Rhythmic nerve impulses coming from the senses to the nerve cells of the cortex, may under different conditions have two effects on them: or lead to an active, excited state, or, conversely, inhibit this active state, turn off the nerve cells from work.
To be continued in the next part https://zen.yandex.ru/profile/editor/id/5d9330af8600e100b06bbabe/5d949151027a1500b118270c/edit