4 Answers

  1. I came across lectures by Avakumov S. V. (Ph. D. is engaged in the study of dreams) in which he spoke (based on specific research) about a certain mechanism that blocks the passage of a signal, excitation to effectors (to muscles, for example). The immaturity of this mechanism in childhood is explained by sleepwalking. It is necessary so that a living being does not kill itself in its sleep.

    In theory, many of the neurons that are used in real action are excited in a dream. Why does the brain need special neurons for sleep and for real life? This is uneconomical.

  2. There are several phases of sleep. One of them is called the phase with fast eye movements – in English rapid eyes movies, abbreviated as REM. It is at this time that a person dreams, and if at this moment you look at the brain activity on an electroencephalogram, it will be similar to that of a waking person. REM-phase is also called paradoxical-all the muscles of the body are in maximum relaxation. That is why when you dream that you are walking, you cannot move a single muscle in reality.

  3. In general, such a “structure” of the brain as the reticular formation plays an important role in this. It is a network of diffusely located neurons located throughout the brain stem, up to the thalamus. It selectively activates or slows down the cerebral cortex (ascending RF) or spinal cord centers(descending RF), thereby controlling the activity of the brain and the body. (In general, it performs just a lot of functions, including participating in breathing, regulating vascular tone, etc.)

    And it is the descending RF during sleep that gives collaterals to the anterior motor neurons of the spinal cord and slows them down during sleep, thus motor commands are simply not executed.�

    In addition, many sleep centers (the preoptic nucleus of the hypothalamus, the gray circulatory substance of the brain, etc.), during sleep, slow down many structures responsible for movement (yes, the same cortex of the brain and basal nuclei), and their activity decreases.

    I didn't see the answer from a physiological point of view, so I decided to write))

  4. Sometimes, you can encounter such an extremely rare phenomenon as”Sleep paralysis”. The same notorious mechanism that blocks muscle activity continues to work when the brain is already awake and the person cannot move a single muscle. This condition is quite unusual and frightening, and it lasts no more than 20-30 seconds. If you don't know what you're dealing with, you can get really scared. I had this, but I know it, I'm not afraid ; )

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