Sleep stage

The first stage (or the first stage): the sleep stage. Start from drowsiness, gradually fall asleep, and no longer stay awake. At this time, breathing slows down, muscle tension decreases, and the body relaxes slightly. At this time, it belongs to the initial sleep state, and sleepers are more likely to be awakened by external sounds or touches.

Shallow sleep stage

The second stage (or second stage): light sleep stage, or light sleep stage. Sleep at this stage belongs to light or moderate sleep state, and sleepers are not easy to be awakened. At this time, the muscles are further relaxed, and EEG shows spindle sleep waves.

Deep sleep stage

The third stage (or the third stage): deep sleep stage, the sleeper enters a deep sleep state, muscle tension disappears, muscles are fully relaxed, sensory function is further reduced, and it is more difficult to be awakened.

Continue the deep sleep stage

The fourth stage (or the fourth stage): continuing the deep sleep stage, which is an extension of the third stage, but not every sleeper can reach this stage, nor can every sleep cycle reach this stage. Some people can't reach this stage if they don't sleep deeply enough, or they only have a short sleep in the third and fourth stages.

[Edit this paragraph] Typical behavior

Lucid dream

Lucid dream, also called lucid dream, is a state in which you realize that you are dreaming, and then you can control the dream. It is generally believed that lucid dreams occur because the short-term memory part that should be closed during the rapid eye movement (REM) period, because some stimulus (that is, the cognition of "I am dreaming") resumes activities, but the part in charge of dreams is not closed, so it becomes a state in which dreams can be controlled. According to the current research, lucid dreams have no physiological or psychological influence on people.

Night terrors (night terrors)

Night terrors occur in non-rapid eye movement sleep, which is the deepest sleep. It is a reaction of being "awakened" when the fear center of the brain is suddenly and inexplicably activated. In fact, it is not correct to say "awakened by fear", because although the action is very similar to being awakened by fear, people are still asleep and will not remember that they have experienced this period after waking up. By contrast, it's unlucky to sleep next to the person next to your pillow! The incidence of night terrors in children is much higher than that in adults. If adults have night terrors, pay attention to whether diet and sleep are out of balance, and at the same time pay attention to whether this may be a precursor to narcolepsy.

Sleepwalking (sleepwalking)

Sleepwalking is similar to night terrors, both of which occur at the deepest non-REM sleep, except that sleepwalking is the start of the whole brain, not the short-term start of the fear center. Most people "sleepwalk" don't really get up and walk, just sit up, look around, mumble something, and then fall asleep. There are not many examples of getting up and walking for dinner, but what is more serious is that some people get up and clean, take a shower, dress (change back into pajamas before going to bed), drive, dance and have sex (! ), and even an example of murder. Sleepwalkers' eyes are open, and they don't grope with their eyes closed as most people think, but their eyes are blank, and they may not respond after being called for a long time. The question now is, is the sleepwalker completely unconscious, or is he actually conscious and just can't remember it afterwards? Scientists have no answer to this, but from the analysis of brain waves, it seems to be inclined to the former. Therefore, your body can operate on its own without your intervention at all. Eating (dreaming), talking (talking) and having sex in sleepwalking are often studied as three independent diseases.

Sleep paralysis (sleep paralysis)

Also known as "ghost press". When sleeping, the human movement center will be shut down to avoid the actions in dreams being reflected in reality and causing injuries. Sleep paralysis is a state in which the consciousness is awake, but the motor center is still closed, so although awake, the whole body can't move, only the eyes and eyelids can move. The most terrible thing is that while sleeping paralysis is often accompanied by auditory and visual hallucinations, you will hear small sounds and ghosts. Why is Xiao Jiang so clear? Because of this situation, Xiao Jiang has met at least 50 times. Some experiences ... are really as wonderful as watching ghost movies, and they happen when they happen. If you can't hide, just try to fall asleep as soon as possible or simply wake up. Probably the most terrible thing is to wake up falsely, that is, you think you are awake, but you are still dreaming, the feeling of being relieved and then scared.

Rapid eye movement behavior disorder

(Rapid eye movement behavior disorder) To some extent, this is just the opposite of sleep paralysis. Rapid eye movement behavior disorder means that consciousness is still asleep, but the motor center is in a "awake" state. At this time, people will begin to react to the behaviors in their dreams, such as swatting flies, hitting people and running. REM behavior disorder is different from sleepwalking-one is before REM (not dreaming) and the other is during REM (dreaming). Some scientists think this is one of the precursors of Parkinson's disease.