Session 1 — How Sleep Actually Works

# Session 1 — How Sleep Actually Works

What is sleep? Well, if you say that sleep is just the opposite of wakefulness, it means not to say anything. You still need to highlight what is not in the state of wakefulness, but is in sleep. First of all, of course, this is a disconnection from the outside world. A person in sleep does not react to external irritants, it is difficult to push him away, it is difficult to bring him back to wakefulness. This means that it is necessary for something. it means that the body needs to periodically switch to such an isolated mode in order to perform some important functions for health and life. So, first of all, the state of sleep

is characterized by a decrease in the reaction to external stimuli. This is the first feature of sleep. The second feature is that it is a regular, natural state. There are similar states of sleep, for example, hypnosis, anesthesia, but these are unnatural and irregular states, although they look the same as sleep. In these cases, we have to make special efforts to introduce a person into hypnosis in order for him to disconnect from the outside world. And sleep comes regularly, not at the same time, but every day. And apparently it is embedded in the genetic system, somewhere there are genes, they are still not determined, which make us immerse ourselves in this state once a day.

The second feature of sleep, which distinguishes it from wakefulness, is the predictability, the obligation to sleep almost every day. You can try not to sleep, of course, but we will not have enough time. And we will also talk about this, how much you can really not sleep. The third feature of sleep is its heterogeneity. When scientists began to study sleep in the real sense, when there was an opportunity to look inside the activities of the nervous system or internal organs during sleep without waking up a person, it turned out that the body works during sleep in a different way than the state of awakening. In some periods of sleep, brain activity is sharply reduced, but in some periods of sleep, for example, when we see a dream, brain activity can be even more pronounced than in a state of agitation. That is, sleep is also a special adjustment of the activity of the nervous system, internal organs. Apparently, some processes

are happening at this time, I will tell you more about them, which can only happen when switching to this amazing state of sleep. And another feature of sleep is that it is typical for animals and people to have a nervous system. This connection of nerves, so to speak, and the state of sleep, apparently, is also necessary, because it is the nervous system that controls all the life processes in our body. The hormonal system also controls it, but the nervous system controls it to a greater extent. And, accordingly, this transition to a special state is ensured by impulses, which, at a certain time, begin to pass the nervous system in order to transfer the body to this new mode. And one more, already the fourth feature of sleep is its amazing predictability. In the wake, we do not know what will happen to us.

And in sleep, we know that in an hour and a half the same thing will happen. For some reason, all the processes, all these pictures of the activity of the body, which we observe during the study of sleep, they are repeated about every hour and a half. You know, there is a slow wave sleep, a fast sleep, a sleep with fast eye movements. And these parts of sleep, not every hour and a half, are renewed again and again. It is still not clear why nature is so arranged that these repeated processes should happen several times. Where did this predictability come from?

There is a difference between the state of sleep and the state of enlightenment, and from many other states. In fact, enlightenment is not the only state of the body and consciousness. There is the state of minimal consciousness, comatose state, dementia, and so on. But today, and in our next classes, we will talk, of course, about sleep.