The normal state of the brain is in three states: awake (active), non-REM, and REM. Humans are active for about 16 hours. On the other hand, we spend one-third of the day, or 8 hours, asleep. We spend 33% of our lives asleep. Of these 8 hours of sleep, 6 hours are non-REM and 2 hours are REM. When you sleep with your neck upright and behave well, that is non-REM sleep. When you sleep lying down or with your eyes moving behind your eyelids, that is REM sleep. It is said that ensuring deep non-REM sleep guarantees good health. Non-REM sleep is a time of rest that calms the cerebrum and restores its functions.
In today’s world, where information is overloaded due to the sophistication of modern society, memory has become excessive and brain fatigue has become a constant condition. In this situation, it has gradually become understood that forgetting ability is just as important as memory. People who are troubled by information overload have devised various ways to forget. There are various ways to forget, such as moving the body, sweating, and getting absorbed in an interesting game. People who are good at their jobs are also praised for being good at playing. If you forget poorly, there is a risk that your brain will become like a garbage warehouse. REM sleep suggests the importance of forgetting. REM sleep works to dispose of unnecessary things in your head (excessive knowledge, unpleasant stimuli, etc.), in other words, it works to encourage forgetting. When people sleep, they undergo REM sleep to dispose of unnecessary things in their heads. REM sleep is like cleaning your head, and it occurs not just once, but many times a night. If you wake up in the morning with a clear head, it is thanks to REM sleep.
Our ancestors were in a position to be targeted by dinosaurs and carnivorous beasts. When attacked by dinosaurs, a behavioral pattern of quickly fleeing evolved. There is a theory that this was the state of REM sleep. For humans, not being able to sleep deeply was also an important ability for survival. It is said that good sleep alternates between non-REM and REM sleep in a 90-minute cycle. During deep non-REM sleep, growth hormone, which is involved in growth and repairing physical injuries, is secreted. This hormone is necessary for normal growth and development. When bacteria or viruses invade the body, the defense mechanism kicks in, inducing non-REM sleep and producing immune substances. REM sleep works to eliminate unpleasant emotions. These two types of sleep protect the mind and body.
