Four elements of healthy sleep

Author: Chen Kui, Chief Physician, Beijing Friendship Hospital, Capital Medical University

Reviewer: Zhou Lichun, Chief Physician, Beijing Chaoyang Hospital, Capital Medical University

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Sleep is the guarantee of human health. Without good sleep, there is no health. However, everyone's evaluation of their own sleep is just a subjective feeling: some people feel that they sleep well and snore loudly when they sleep, but in fact, the quality of sleep is not good. They may have sleep apnea and intermittent hypoxia; some people feel that they did not sleep well after waking up, but in fact, they slept well.

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So how do we evaluate sleep quality? This requires an objective assessment of sleep.

In fact, how long a person sleeps, how deep he sleeps, how well he sleeps, when he falls asleep, and when he wakes up all have their own operating rules. Each person's sleep depends on his own daytime needs (internal factors) and the natural and social environment (external factors).

To evaluate whether your sleep is good or not, you need to conduct a comprehensive assessment based on your own feelings and the sleep testing instruments.

After waking up, the feeling of the sleep just passed is actually quite subjective. These subjective feelings can give doctors corresponding hints, but the sleep process has its own objective behavior. Doctors can use sleep monitoring instruments to scientifically and rationally analyze the human body's sleep process and answer how the individual slept, whether they slept well, whether they have sleep problems and sleep disorders, etc.

Studies have found that healthy sleep depends on the balance of four aspects, namely the four elements of healthy sleep.

The first and second factors are what each of us can roughly determine through perception, namely sleep rhythm and sleep duration.

Sleep rhythm refers to when you can fall asleep and when you can wake up. From a health perspective, everyone needs to live according to their own sleep rhythm. Sleep rhythm is mainly regulated by the body's biological clock. The biological clock is also the circadian rhythm, which interacts with the external environment to promote the body to fall asleep. Because everyone's biological clock is different, don't copy it rigidly. Some people belong to the early bedtime and early rise type (fall asleep before 9 pm), some people belong to the late bedtime and late rise type (fall asleep after 2 am), and most people are in between the two. People with different biological clocks are suitable for different social work. If you usually go to bed late and get up late, and there is no major change in your daytime life, choosing to go to bed at 8-9 pm will only make you toss and turn, difficult to fall asleep, and increase anxiety. Therefore, it is most important to choose a sleep rhythm that suits your life.

Once you have roughly determined your bedtime and wake-up time, you can calculate your sleep duration. However, it should be noted that people of different ages need different sleep durations, and different individuals of the same age also need different sleep durations. For example: newborns (0-3 months) need 14-17 hours; infants (4-11 months) need 12-15 hours; toddlers (1-2 years old) need 11-14 hours; preschoolers (3-5 years old) need 10-13 hours; school-age children (6-13 years old) need 9-11 hours; adolescents (14-17 years old) need 8-10 hours; adults (18-64 years old) need 7-9 hours; and the elderly (over 65 years old) need 7-8 hours. In fact, the length of sleep depends on daytime needs and the external and social environment.

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The third and fourth elements cannot be accurately perceived by the human body and can only be scientifically analyzed through sleep monitoring instruments. They are sleep structure and sleep quality.

Combined with the inspection instrument, the normal sleep of the human body can be divided into three states: the first is the N1 and N2 stages of non-rapid eye movement sleep, which is also the shallow sleep stage; the second state is the N3 stage of non-rapid eye movement sleep. During this period, a large number of high-amplitude slow waves appear in the EEG, so it is also called slow-wave sleep, commonly known as deep sleep, which is high-quality sleep; the third state is the rapid eye movement sleep stage, which is characterized by dreams. After waking up, you feel like you have woken up from a dream. During this period, the muscles of the whole body are completely relaxed, and the EEG is similar to the awake state, but in fact you are still sleeping. These three states alternate and reciprocate throughout the sleep process to form a regular sleep structure. Normal sleep starts from shallow sleep, to deep sleep and then to the dreaming stage, thus forming a cycle, and then repeats to form the entire sleep process at night. Calculated based on an adult sleeping 7 to 9 hours a night, it can be cycled 4 to 6 times. If there is a problem with the sleep structure, it is often a manifestation of certain diseases, such as narcolepsy.

Sleep quality mainly refers to the N3 stage of non-rapid eye movement sleep (deep sleep or sleep stage 3), which accounts for 15% to 25% of the total sleep of adults. The total amount of deep sleep varies with age and work activities. Studies have found that the driving force of deep sleep is sleep pressure. The longer the awake time, the more endogenous hypnotic substances are produced in the brain, which prompts the body to enter deep sleep. Both mental and physical labor can increase sleep pressure, while caffeine in coffee or strong tea, naps, and naps will reduce hypnotic substances in the brain and reduce sleep pressure. Generally speaking, deep sleep is efficient sleep, and it is difficult to wake up with external stimuli. This period is the most efficient stage for the human body to repair daytime damage, eliminate fatigue, and restore mental, physical, and energy. It is also the most important part of evaluating sleep.

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