People spend almost a third of their lives doing one thing: sleeping. Every year there is a day for people around the world to celebrate the 1of good and healthy sleep-World Sleep Day.

Sleep is like food for the 2. A good amount of sleep helps the body and brain grow and 3People of different 4need different amounts of sleep. According to the National Sleep Foundation in the US, 5need seven to nine hours of sleep every night. For students aged 10 to 17, a (n) 6amount is about eight to nine hours per night.

 7 ， many students don't get enough sleep because of early school start times and too much homework. The China Youth and Children Research Center reported that about 80 percent of middle school students don't get 8  sleep.

A lack(缺乏)of sleep can 9 influence a person's life. Students 10 don't get enough sleep may get poor grades. They cannot pay 11 in class or do well in sports.

To solve this problem, scientists advise that students should have 12schoolwork and more time to sleep. There are some other ways to help people get enough sleep, such as 13 a 20-minute nap during the day. Good sleep habits are also 14For example, try to go to sleep and wake up at the same time every day,  15on weekends and during holidays.