Cái nào thì hợp lý ạ `-` Sleep is very important. A person who does not sleep dies faster than a person who does not eat. We spend about a third of our lives in sleep. Thats about 121 days a year! `-`How much sleep do we need? We are all different. A baby needs 16 hours of sleep every day. Children from 6 to 12 years old need an average of 10 to 12 hours of sleep. Teenagers need 9 to 10 hours of sleep. And adults need an average of 7 to 8 hours a night. There are some people who need only 3 hours of sleep. Others need 10 hours of sleep. `-` After the age of 50, the average sleep time goes down to 6.5 hours a night. We need less sleep as we get older. About one in three Americans has a problem with sleep. Many of these people cannot fall asleep. The name of this problem is insomnia. Some people say, I didnt sleep all night. But thats not really true. They may sleep lightly and wake up several times. In the morning, they only remember the times they were awake, so they think they were awake all night. This is not a new problem. `-` Many famous people in history had insomnia. Some of these people had special ideas to make them sleep. Benjamin Franklin had four beds. He moved from one to another to fall asleep. Mark Twain had a different way. He lay on his side across the end of the bed! $--------------$ What is the main idea of the passage? $A.$How to say healthy and keep fit $B.$ Sleep more to make you healthier $C.$ General knowledge about sleep $D.$ Different people need different hours of sleep every 1day