Beijing children will have more time to sleep when the new semester begins on Monday, as the city's education authority has ordered primary and middle schools not to begin classes before 8 am.
According to the notice issued on Friday, which postpones the start of the school day by 20-30 minutes, the city's education bureau also stated that pupils should spend no more than eight hours a day in classes.
Shanghai introduced a similar rule at the end of last year ordering primary schools not to start classes before 8:15 am, while secondary schools should not begin lessons before 8 am.
Health experts have said a lack of sleep may damage the brain, especially the part that deals with learning and memory.
"Exhaustion may also affect children's psychological health. It could affect a person's appetite and make them prefer high-calorie foods, so that obesity becomes an issue," said Li Lite, a nutrition professor of China Agriculture University.
To ensure students get enough physical exercise at school, Beijing's education bureau also asked schools to add 10 more minutes a day to the current 60 minutes of sports and recreation time in primary and secondary schools from the beginning of next month.
The Ministry of Education last year called on schools to revise timetables to allow students to get enough sleep - 10 hours for primary school students, nine hours for junior high school students and eight for senior high school students.
A study by the ministry late last year found that teenagers' average physical index, such as endurance, strength and speed, had been declining continuously in recent years.
The number of teenagers with poor eyesight remained high and the number of overweight urban teenagers kept increasing, the study found.