World Sleep Day，organized by the Would Sleep Day Committee of the Would Association of Sleep Medicine since 2008，is held on March 21 every year.
The aim of World Sleep Day is to celebrate the benefits of good and healthy sleep. Events involving discussions，presentations of educational materials and exhibitions take place around the world and online.
Sleep quality plays a key role in people’s health. Researchers say that there are a lot of advantages if we always get enough sleep. We can be smarter，thinner，healthier and more cheerful. Also we’re to have better skin，better memories and longer lives. When you lose even one hour of sleep for any reason，it will influence your performance the next day.
In general，adults are thought to need at least eight hours of sleep a night，but a recent survey found that，on workdays，only 21% of them really get a full eight hours of sleep，and another 21% get less than six. For teenagers，a healthy amount is about eight to nine hours per night. However，about 80% of high school students don’t get enough sleep because of their schoolwork or some bad habits.
27% of people throughout the world have sleep problems. Now there are over 80 kinds of sleep disorders，and most people know little about their danger. So，for our good life and work，it’s necessary for us to realize the importance of sleep and try to have a good sleep.
How long has World Sleep Day been celebrated so far？
 
What is the purpose of World Sleep Day？
 
What will happen if we sleep one hour less than we should？
 
Why don’t most high school students have enough sleep？
 
What suggestion will you make about our better sleep？（请自拟一句话作答）