There are many ways to help improve your health like eating healthy food，taking exercise and getting medical help.But the easiest and cheapest way to improve your health is just to sleep eight hours or more every night.The general sleeping rule is that the younger you are，the longer sleep you need.
   The problem with sleep is that more and more people in the world are not sleeping enough.The World Health Orientation （WHO） says，over half of the people in the world may be sleep-deprived （睡眠不足的）.Having less sleep not only makes people feel tired but also causes accidents.In the United States alone，sleepy drivers cause at least 100，000 traffic accidents a year.
   Also，sleep problems can cause medical problems，such as high blood pressure.
   Why are so many people sleep-deprived？Part of the reasons may be cultural.In the American culture，people put a higher value on work than on sleep.In fact，people who sleep a lot are usually seen as "lazy".Also，you can sometimes hear some people say proudly that they don't have much time to sleep.They only sleep four or five hours a night.It seems that the less you sleep，the more work you'll do.
   How do we teach these people to learn the value of sleep？Perhaps they may listen to the advice of Dr.James Maas，an expert in sleep.He says， "Sleep is like a credit （信用） card.When you sleep less，you are only borrowing time.You always have to pay it back.The more hours you don't sleep，the more hours you should sleep to 'pay back' the hours on your 'sleep credit card'. "
   For those who value work more than sleep，they should listen to what a famous person once said， "Don't think you will be doing less work because you sleep during the night.That is a foolish idea which is held by people who have no imagination.You will be able to do more. "

（1）We can improve our health through

many ways

many ways

but the easiest and cheapest way is to sleep

at least

at least

8 hours every night.
（2）More and more people in the world don't have

enough sleep

enough sleep

.

According to

According to

the WHO，over half of the people in the world may be sleep-deprived.
（3）In the American culture，people think that work is

more valuable

more valuable

than sleep.It seems that sleeping less means

doing more work

doing more work

.
（4）

Listening to

Listening to

the advice of Dr.James Maas may help people learn the value of sleep.He says，we need to

pay back

pay back

the hours on our sleep credit card if we get less sleep.
（5）A famous person once told that it was

foolish

foolish

of you to consider that you would be doing less work

because of

because of

sleeping during the night.