Children's sleep often accounts for one-third to one-half of their daily routine, making it a topic of great concern for parents. Urging children to go to bed early at night and wake up early in the morning has become a daily chore for many parents. Indeed, many parents have come to consult the CDC (Center for Disease Control and Prevention) about their children's sleep issues, and we aim to clarify everything in one article!

Parent's Question:
My child always stays up late on weekends and can't wake up early on school days. Should I intervene?

CDC's Answer:
Generally, due to the influence of the body's internal clock, sleep and wakefulness follow a certain physiological rhythm. Simply put, without external interference, a person's daily routine of feeling sleepy at night and waking up in the morning remains relatively fixed.

Therefore, it's challenging for children to quickly adjust their body clocks between weekends and weekdays. If they get used to staying up late and waking up late on weekends, but fail to go to bed early the night before schooldays and are forced to wake up early due to school, they won't get enough quality sleep, resulting in a "sleep debt." However, this debt must be repaid. To maintain internal balance, the body adjusts the original body clock to repay this debt, making it difficult to stay alert during the day, and they may even doze off in class.

We recommend that parents urge their children to maintain a regular sleep schedule and avoid indulging in late nights and late mornings on weekends, thereby ensuring both sleep quality and academic performance.

Parent's Question:
When should children go to bed at the latest? How many hours of sleep do they need each day?

CDC's Answer:
People of different ages have varying sleep needs, which are influenced by many factors, including physical condition, psychological stress, sleep environment, diet, and daily sleep habits. These factors' impact on sleep changes with age.

Sleep is closely related to brain development in children, so they generally require more sleep than adults. Newborns need 16-20 hours of sleep daily, while 2-5-year-olds sleep and wake up for roughly equal periods, totaling about 12 hours.

For primary and middle school students, according to the Ministry of Education, elementary school students should get 10 hours of sleep per day, junior high school students 9 hours, and high school students 8 hours. Bedtimes for these age groups should generally be no later than 21:20, 22:00, and 23:00, respectively.

Parent's Question:
I didn't realize children need so much sleep. Why is sleep so important?

CDC's Answer:
People spend about one-third of their lives sleeping, which is crucial for our health. During sleep, body temperature, heart rate, and blood pressure drop, and breathing slows down, helping eliminate fatigue and restore energy. For children and adolescents, sleep promotes brain development, consolidates memory, and ensures optimal brain function.

Another key factor is "growth hormone," which is vital for children's growth and development. Its secretion is closely related to sleep; more is secreted during sleep, and less during wakefulness. Therefore, good sleep is crucial for promoting growth and enhancing immune function in children and adolescents.

Parent's Question:
If sleep is so important, what other harm does insufficient sleep cause?

CDC's Answer:
Apart from the conventional benefits mentioned, insufficient sleep can also indirectly lead to overweight/obesity, myopia, and mental health issues in children.

For instance, when children are sleep-deprived and can't wake up on time, parents often opt for convenient packaged sweets or fast food for breakfast on the way to school, which are high in fat and carbohydrates, increasing the risk of overweight/obesity and conditions like hypertension, hyperlipidemia, or diabetes later in life.

Moreover, children spend most of their daytime focusing on studies and homework. Sleep deprivation can leave them exhausted and unwilling to engage in outdoor activities, increasing the risk of myopia.

Sleep deprivation can also affect children's mental health, leading to anxiety and hyperactivity.

Parent's Question:
If insufficient sleep has so many drawbacks, does that mean the longer the better? How much sleep should children get?

CDC's Answer:
Studies show that excessive sleep can impair brain function, increase the risk of diabetes, and potentially even cancer. Thus, both too little and too much sleep can be problematic. The optimal sleep duration varies by individual. There's no standard or precise answer to "how many hours and minutes of sleep do I need every day?" Just as Gu Ailing claims to need 10 hours of sleep, some successful people function well with just 4 hours. Research also indicates that certain genetic mutations can reduce lifelong sleep needs. For minors, the National Sleep Foundation recommends no more than 11 hours for 6-13-year-olds and 10 hours for 14-17-year-olds.

In summary, if you wake up feeling refreshed and stay alert throughout the day, you're getting adequate and quality sleep.

Parent's Question:
My child sleeps the recommended hours, but still feels lethargic during the day. What can I do?

CDC's Answer:
Good sleep depends not only on duration but also quality, i.e., the proportion of deep sleep and REM (Rapid Eye Movement) sleep in the overall sleep cycle. Without professional equipment, it's difficult to monitor these phases, but we can assess sleep quality through observation:

• Falling asleep quickly within 5-15 minutes after getting into      bed.

• No snoring or frequent awakenings during sleep.

• Feeling refreshed and alert the next day, without dozing off in      class and having high learning efficiency.

Poor sleep quality can leave one feeling tired even after sufficient sleep. Thus, to enhance daytime learning efficiency, focus on both sleep duration and quality.

Parent's Question:
It seems sleep quality is crucial too. Are there any tips to improve it?

CDC's Answer:
Here are some tips:

1. Develop and stick to a consistent sleep schedule with your      child.

2. Establish good sleep habits, like avoiding caffeine or heavy      meals before bedtime, limiting screen time to 2 hours daily, and      refraining from using electronic devices half an hour before sleep.

3. Encourage physical activity, but not within 2 hours of bedtime.

4. Create a comfortable sleep environment.

Parent's Question:
Can you elaborate on creating a comfortable sleep environment?

CDC's Answer:
Sure, here are some suggestions:

• Use suitable bedding, such as a moderately firm mattress, a      pillow of appropriate height, and breathable bedding, which should be      regularly cleaned and aired.

• Keep bedroom noise below 30 decibels, similar to a clock      ticking.

• Dim the lights by drawing curtains and turning off overhead      lights for a soft, dim environment.

• Ventilate the bedroom daily for fresh air.

• Use screens or insect repellents to avoid disturbances from      flies or mosquitoes.

• Maintain an optimal temperature of around 23°C and humidity of 40%-70%, using a humidifier in autumn and      winter if necessary.

Parent's Question:
You mentioned that physical activity can improve sleep quality. With school starting and increased academic pressure, are there specific requirements for physical activity?

CDC's Answer:
Yes, China's 2017 "Physical Activity Guidelines for Chinese Children and Adolescents" recommends:

• Children and adolescents should accumulate at least 60 minutes      of moderate-to-vigorous physical activity daily, such as gymnastics or      cycling.

• Engage in high-intensity physical activity and resistance      training for muscle strength and bone health for at least 3 days a week,      including exercises like sit-ups, running, football, or basketball.

• Limit screen time to 2 hours per day.

Source: Shanghai CDC