When we fall asleep, will the brain shut down like a computer and lose consciousness?
In fact, the brain continues to function during sleep. These changes in brain waves have led sleep experts to discover that sleep can actually be divided into four different stages.
What are sleep stages?
The normal human sleep structure cycle can be divided into two periods: non-rapid eye movement sleep (NREM) and rapid eye movement (REM). Among them, the period of non-rapid eye movement sleep (NREM) can be divided into three stages (that is, the first, second, and third stages). NREM and REM appear alternately, alternating once as a sleep cycle. There are usually 4-5 sleep cycles every night, and the duration of each cycle is about 90-110 minutes.
What is non-rapid eye movement sleep (NREM)?
Non-rapid eye movement sleep can be divided into three stages from light to dark. Usually during non-rapid eye movement sleep, the heart rate, blood pressure, and body temperature will gradually calm down, which helps to secrete growth hormone and restore physical strength.
- The first stage
When sleep begins, you will feel drowsy. At this time, brain waves begin to change, with smaller amplitudes. It accounts for 2%-5% of our sleep throughout the night. People at this stage are easily disturbed or awakened by the outside world.
- The second stage
It belongs to the stage of formal sleep, light sleep. The brain waves show irregular changes, and the slow-moving eyeballs will be interrupted. Brain waves continue to slow down with specific bursts of rapid activity, called sleep spindle, mixed with sleep structures called K complexes.
- The third stage
Deep sleep stage, it is not easy to be awakened. At this time, the brain wave changes greatly, the frequency is only 1-2 weeks per second, but the amplitude increases greatly, showing a slow-changing curve. Insomnia (sleepwalking, sleep talking or sleep disturbances and night terrors) occurs in the deepest stage of sleep.
What is the rapid eye movement period (REM)?
It is a sleep stage with rapid eyeball movement. The first time it often occurs about an hour after falling asleep. This is an important stage of our dreams. Brain waves change rapidly, and brain waves with high frequency and low amplitude similar to those in the waking state appear. Sleepers are easily awakened. People who are awakened during REM may feel drowsy or tired.
How to sleep scientifically?
Reasonable sleep should be 7-9 hours a day. Studies have shown that people who develop the habit of going to bed early and getting up early have less mental stress and are in a healthier state. The best time to fall asleep every day is from 10 o'clock to 10:30 in the evening, half an hour or an hour later to enter deep sleep. 12 midnight to 3 am is the best time for the human body to naturally enter deep sleep and keep you energetic.