阅读理解①Eating good food and getting proper exercise are important to stay healthy. Getting enough sleep is important, too. Experts say that teenagers between the ages of 15 and 20 need 8 to 10 hours of sleep each night.
②Your body needs to take a rest from all the activities it has done during the day. Your brain needs a rest, too. You are likely to get sick easier without enough sleep.
③You have a "24-hour clock" inside your body that tells you when to be awake and when to go to sleep. ▲ Blue light that comes from the Sun tells your brain to keep you awake during the day. When there is no blue light at night, the brain tells the body that it's time for sleep.
④There are many things that stop the brain from telling your body when it's time to sleep. One of these is blue light at night. Today, people spend a lot of time watching television or looking at screens on computers or smart phones. These devices (装置) give off blue light. If you look at them at night, the blue light can trick your body into thinking it's daytime. Then it is more difficult to go to sleep.
⑤What should you do to get good sleep? Experts say that you shouldn't look at screens that give off blue light for at least one hour before going to sleep.
⑥ Do not watch TV or use anything with a computer screen in bed. If you need to do something to fall asleep, it is better to read a book. Also, keep your bedroom as dark as you can. This will help you sleep well.
