初三英语阅读,is not unusual to see your desk-mate yawn as he complains that he didn'tIt is not unusual to see your desk-mate yawn（打呵欠）as he complains that he didn't have a good sleep the night before.Many teens don't get enough sleep

初三英语阅读,is not unusual to see your desk-mate yawn as he complains that he didn'tIt is not unusual to see your desk-mate yawn（打呵欠）as he complains that he didn't have a good sleep the night before.Many teens don't get enough sleep
初三英语阅读,is not unusual to see your desk-mate yawn as he complains that he didn't
It is not unusual to see your desk-mate yawn（打呵欠）as he complains that he didn't have a good sleep the night before.Many teens don't get enough sleep because they have too much homework,which keeps them up at night.Some teens cannot sleep at night even when they want to.
Studies show that during your teenage years,the body's biological clock is reset,telling you to sleep later at night and wake up later in the morning.
But changes in the body clock aren't the only reason teens lose sleep.Lots of people have insomnia（= being hard to sleep）.The most common reason of insomnia is stress.But all sorts of things can lead to insomnia.These include physical discomfort,emotional troubles（like family problems or relationship difficulties）and even sleeping environment（a room that's too hot,cold or noisy）.
It's common for everyone to have insomnia from time to time.But if it lasts for a month or more,go and see a doctor.
There are a number of other conditions that can affect your sleep.Some teens find they wake up during the night because of leg or arm movements.These sudden and dramatic movements are out of your control.Other uncomfortable feelings include itchiness（痒）or cramp（抽筋）,which make you want to move.Doctors say that it is mainly because of having too little iron（铁）．Some people have a condition that causes stomach acid（酸）to move backward towards the chest.This produces the uncomfortable,burning feeling called heartburn.So even if the person doesn't notice the feelings of heartburn because he is sleeping,he may feel tired the next day.
Most teens have nightmares sometimes.But,if they happen often,a person's sleep pattern can be seriously affected.The most common cause of nightmares is emotional problems,such as stress or worry.If you have them a lot,it's a good idea to talk to a doctor.
Doctors encourage teens to make lifestyle changes to develop good sleeping habits.You probably know that coffee can keep you awake,but did you know that playing video games or watching TV does the same?
Tips for healthy sleeping:
* Keep regular hours.Try to go to bed at the same time and get up at the same time every day.
* Use the bed just for sleeping.Avoid watching TV,using laptop computers,or reading in bed.
* If it helps to read before sleep,make sure you use a very small wattage bulb（灯泡）to read.A 15-watt bulb should be enough for your reading lamp.
* Don't stress if you feel you are not getting enough sleep as it will just make matters worse.You will sleep in the end.
* Don't take exercise near bedtime.No exercise at least three hours before bed.
* Don't go to bed hungry.Have a light snack; avoid a heavy meal before bed.
* Don't look at the clock if you wake up in the middle of the night.It can cause worry.

初三英语阅读,is not unusual to see your desk-mate yawn as he complains that he didn'tIt is not unusual to see your desk-mate yawn（打呵欠）as he complains that he didn't have a good sleep the night before.Many teens don't get enough sleep
C B A