Do you know the reason why we feel tired in the middle of a class？Maybe you would say it's because the teacher's class is boring.However，the real reason is probably that we don't have enough sleep.Here are what sleep researchers have found about how to sleep.
   Why do we need sleep？Sleep helps our body grow and stay healthy.It also gives us energy，so we can be active all day.Doctors say：When you close your eyes and need a rest，sleep is just the very best!
   How much sleep do we need？It is known that all of us naturally need no less than eight hours of sleep per night.When we sleep below six hours per 24，we're at a higher risk of health problems.Some of us think we can make up any of those hours lost during the week on the weekends.Sadly，there is no storage （儲(chǔ)存）system for sleep in the brain.
    New-born babies can sleep 20-22 hours a day.Children need 10-12 hours of sleep a day.Teenagers need 8-10 hours of sleep a day，while grown-ups usually need 6-8 hours of sleep to keep active.
    A new research suggests a kind of strong connection between purpose in life and sleep.People who have a greater sense of purpose usually have better physical and mental health，which in turn explains their higher-quality sleep.Perhaps developing a sense of purpose in life could be as useful at improving sleep as the healthy habits above.
    If you have trouble sleeping，set a goal and go for it!Maybe it will help you to have a sound sleep!

A Research on Sleep
Introduction	Not getting enough sleep can （1） influence influence our study and work.
（2） Results Results	Reasons for sleeping	?Sleep can not only help our body grow，but also help us remain healthy. ?We can be active in the daytime because sleep makes us （3） energetic energetic .
	Sleep time	People of different ages need different sleep time. ?Sleeping less than six hours a day can （4） increase the risk increase the risk of health problems. ?Making up the lost sleeping hours during the workweek is impossible.
	Connection between purpose of life and sleep quality	?A sense of purpose in life is （5） strongly connected with strongly connected with sleep quality. ?People's higher quality of sleep depends on their better physical and mental health.