[Creative Cultivation Program] What is the best balance between sleep duration and physical health?

Author: Mo Zilong

Reviewer: Ding Heyuan, deputy chief physician of Shanghai Fifth People's Hospital affiliated to Fudan University

When it comes to sleep problems, everyone is basically afraid of it. With the accelerated pace of work, study, and life in modern society, people face great pressure every day, and insomnia or lack of sleep at night has become the norm: middle-aged people lack sleep due to work pressure, students suffer from insomnia due to academic burdens, and the lack of sleep of the elderly is related to aging and the decline of various body functions.

People spend one-third of their lives sleeping, which is a normal physiological need of humans and an indispensable part of health. However, more and more data show that people's average sleep time is decreasing.

According to a survey by the World Health Organization, 27% of people have sleep problems. Insomnia has become increasingly common in my country. According to a survey, the average daily sleep duration of Chinese residents in 2010, 2014, 2016 and 2018 was 8.25, 7.78, 7.69 and 7.16 hours respectively, and the sleep duration has gradually shortened over the years.

The latest "China Sleep Research Report (2022)" shows that less than 8% of the country sleeps for more than 8 hours. At the same time, the sleep quality of Chinese residents is also declining. How can we get enough sleep and sleep well? What is the relationship between sleep and health? At present, sleep problems are related to human health and have even become a social problem.

According to a report from the National Sleep Foundation, Americans sleep an average of 7 hours per night, 1.5 hours less than 100 years ago. One-third of people sleep only 6.5 hours or even less, far less than the 8 hours recommended by most sleep experts.

Several research reports have pointed out that reducing sleep to 6.5 hours or even less for several consecutive months can lead to abnormalities in metabolism, hormones and immune function. Insufficient sleep may be one of the reasons for the current epidemic of obesity, diabetes and cardiovascular disease.

In 2019, a major study led by Professor Zhang Xiaomin of Tongji Hospital of Huazhong University of Science and Technology and published in the top journal "Neurology" showed that if you sleep for more than 9 hours at night and take a lunch break for more than 90 minutes, you will face a higher risk of stroke. In other words, if you sleep "too much", it will also be bad for your body. After 6 years of follow-up, 1,557 cases of stroke were diagnosed, and the diagnostic criteria were based on clinical symptoms and CT or MRI imaging examinations. The researchers analyzed and concluded that people who sleep longer (≥9 hours/night) have a 23% higher risk of stroke compared to those who sleep 7 hours to less than 8 hours/night. People who take a nap for more than 90 minutes have a 25% higher risk of total stroke than those who take a nap for 1 minute to 30 minutes.

That is to say, people who sleep for 9 hours or more at night and take naps for more than 90 minutes are more likely to have a stroke. In this study, the researchers also found a point worthy of everyone's attention. When the sleep time reaches 9 hours or more at night, subjects aged 65 and above and subjects with hypertension, hyperlipidemia or diabetes have a "more obvious" risk of stroke. In addition, overweight people have a greater risk of stroke when they take a daytime nap for more than 90 minutes. In other words, people with underlying diseases have a higher risk of sleeping more, and the worse the health, the more they should avoid sleeping more.

In the article "The Impact of Sleep Duration on Self-Assessed Health and Its Age Differences" in the 3rd issue of Population and Development in 2020, the results of the regression model show that there is a "U"-shaped correlation between sleep duration and self-assessed health. Compared with people who sleep for 8 hours, people who sleep ≤5 hours may increase the risk of poor self-assessed health by 69%, people who sleep for 9 hours may increase the risk of poor self-assessed health by 18%, and people who sleep ≥10 hours may increase the risk of poor self-assessed health by 31%. After controlling for age, middle-aged people who sleep too little have poor self-assessed health, while elderly people who sleep too much have poor self-assessed health.

It is said that staying up late is harmful to the body. It seems that sleeping too much or too little is not a good thing.

Alan Rechtschaffen, a sleep expert at the University of Chicago, thinks that when it comes to the amount of sleep and its effects on health, our basic conclusion is "we don't know," and the optimal amount of sleep may vary by age and gender.

For the scientific sleep time for different age groups, we can look at a reference summarized by relevant research in the United States:

It is recommended that babies aged 1-3 months should sleep for 14-17 hours.

Infants and young children aged 4-11 months are recommended to sleep for 12-15 hours.

Children aged 1-2 are recommended to sleep for 11-14 hours;

Children aged 3-5 are recommended to sleep for 10-13 hours;

Children aged 6-13 are recommended to sleep 9-11 hours;

It is recommended that adolescents aged 14-17 get 8-10 hours of sleep.

For those aged 18-64, it is recommended to get 7-9 hours of sleep;

It is recommended that people over 65 years old sleep about 7-8 hours.

Since the sleep duration requirements for different age groups are different, it is more appropriate for you to decide how much sleep time to get each night. Generally speaking, as long as you feel better when you wake up the next morning without dizziness, headache, or fatigue, you think your sleep is good.

References: (Please note the reference format)

Sleep is a luxury "Xiaokang" 2022 Issue 16 | Ma Chunhui, Shenzhen University

What can save you? Sleep of working people "North China Electric Industry" 2022 Issue 6

Distribution and association of sleep duration, naps and insomnia symptoms among Chinese adults Chinese Journal of Epidemiology 2017 Issue 4 | Zheng Bang, Lin Liling, Yu Canqing

The impact of sleep duration on self-rated health and its age differences "Population and Development" 2020 Issue 3 | Liu Yan, Lai Xiaoxuan, Wu Jilei

Who "stole" the sleep of teenagers? "Decision Exploration" 2021 Issue 7 | Zhang Shoukun, Wang Yang

This article is produced by the Science Popularization China-Creation Cultivation Program. Please indicate the source when reprinting