ost teens need about 8½ to more than 9 hours of sleep each night. The right amount of sleep is essential for anyone who wants to do well on a test or play sports without tripping over their feet. Unfortunately, though, many teens don't get enough sleep.
Why Aren't Teens Getting Enough Sleep?
Until recently, teens were often given a bad rap for staying up late, oversleeping for school, and falling asleep in class. But recent studies show that adolescent sleep patterns actually differ from those of adults or kids.

These studies show that during the teen years, the body's circadiancircadian rhythm (sort of like an internal biological clock) is temporarily reset, telling a person to fall asleep later and wake up later. This change in the circadian rhythm seems to be due to the fact that the brain hormone melatoninmelatonin is produced later at night for teens than it is for kids and adults. This can make it harder for teens to fall asleep early.

These changes in the body's circadian rhythm coincide with a time when we're busier than ever. For most teens, the pressure to do well in school is more intense than when they were kids, and it's harder to get by without studying hard. And teens also have other time demands — everything from sports and other extracurricular activities to fitting in a part-time job to save money for college.

Early start times in some schools may also play a role in this sleep deficit. Teens who fall asleep after midnight may still have to get up early for school, meaning that they may only squeeze in 6 or 7 hours of sleep a night. A couple hours of missed sleep a night may not seem like a big deal, but can create a noticeable sleep deficit over time.

Why Is Sleep Important?
This sleep deficit impacts everything from a person's ability to pay attention in class to his or her mood. Research shows that more than 20% of high school students fall asleep in class, and experts have been able to tie lost sleep to poorer grades. Lack of sleep also damages teens' ability to do their best in athletics.

Slowed responses and concentration from lack of sleep don't just affect school or sports performance, though. The fact that sleep deprivation slows reaction times can be life threatening for people who drive. The National Highway Safety Traffic Administration estimates that 1,500 people are killed every year in crashes caused by drivers between the ages of 15 and 24 who are simply tired. (More than half of the people who cause crashes because they fall asleep at the wheel are under the age of 26.)

Lack of sleep has also been linked to emotional troubles, such as feelings of sadness and depression. Sleep helps keep us physically healthy, too, by slowing our body's systems enough to re-energize us after everyday activities.

How Do I Know if I'm Getting Enough?
Even if you think you're getting enough sleep, you may not be. Here are some of the signs that you may need more sleep:

difficulty waking up in the morning
inability to concentrate
falling asleep during classes
feelings of moodiness and even depression
How Can I Get More Sleep?

Recently, some researchers, parents, and teachers have suggested that middle- and high-school classes begin later in the morning to accommodate teens' need for more sleep. Some schools have already implemented later start times. You and your friends, parents, and teachers can lobby for later start times at your school, but in the meantime you'll have to make your own adjustments.

Here are some things that may help you to sleep better:

Set a regular bedtime. Going to bed at the same time each night signals to your body that it's time to sleep. Waking up at the same time every day can also help establish sleep patterns. So try to stick to your sleep schedule even on weekends. Don't go to sleep more than an hour later or wake up more than 2 to 3 hours later than you do during the week.

Exercise regularly. Try not to exercise right before bed, though, as it can rev you up and make it harder to fall asleep. Many sleep experts believe that exercising 5 or 6 hours before bedtime (in late afternoon) may actually help a person sleep.

Avoid stimulants. Don't drink beverages with caffeine, such as soda and coffee, after 4 PM. Nicotine is also a stimulant, so quitting smoking may help you sleep better. And drinking alcohol in the evening can also cause a person to be restless and wake up during the night.

Relax your mind. Avoid violent, scary, or action movies or television shows right before bed — anything that might set your mind and heart racing. Reading books with involved or active plots may also keep you from falling or staying asleep.

Unwind by keeping the lights low. Light signals the brain that it's time to wake up. Staying away from bright lights (including computer screens!), as well as meditating or listening to soothing music, can help your body relax.

Don't nap too much. Naps of more than 30 minutes during the day may keep you from falling asleep later.

Avoid all-nighters. Don't wait until the night before a big test to study. Cutting back on sleep the night before a test may mean you perform worse than you would if you'd studied less but got more sleep.

Create the right sleeping environment. Studies show that people sleep best in a dark room that is slightly on the cool side. Close your blinds or curtains (and make sure they're heavy enough to block out light) and turn down the thermostat in your room (pile on extra blankets or wear PJs if you're cold). Lots of noise can be a sleep turnoff, too.

Wake up with bright light. Bright light in the morning signals to your body that it's time to get going.

If you're drowsy, it's hard to look and feel your best. Schedule "sleep" as an item on your agenda to help you stay creative and healthy.

對于大多數青少年來說，8.5-9個小時的睡眠是必需的。適量的睡眠是保證大家考試能正常發揮，運動能不絆到腳的關鍵。但可惜的是，許多青少年都沒有足夠的睡眠。

為什么青少年不能得到充足的睡眠？

一直以來，人們都會指責青少年晚上睡的太晚，上學睡過頭以及上課時間睡覺。但是最近的研究表明，青少年的睡眠模式與成年人或小孩有本質區別。

這些研究指出，在青春期期間，青少年身體的24小時生理節奏（有點類似體內的生物鐘）被臨時重置， 從而導致青少年睡的更晚，醒的更遲。24小時生理節奏的改變可能是由于青少年在夜間產生的大腦荷爾蒙褪黑激素比大人和小孩都更晚。而這也同樣能使青少年更晚入睡。

這些體內24小時生理節奏的改變與我們在較忙碌時期的改變一致。大多數的青少年都承受著比自己幼年時期更大更緊張的學習壓力，且他們只有通過更努力學習才能克服這些壓力。同時，青少年還有其他時間上的要求---運動，一些課外活動，以及為了上大學攢錢而做兼職，等等。

某些學校較早的上課時間可能也是導致睡眠不足的原因之一。假如青少年在午夜之后才睡但又得起早去上學，這就意味著他們一天只能擠出6-7個小時睡覺。一個晚上少幾個小時的睡眠不會產生什么大問題，但是長期少眠就會造成嚴重的睡眠不足。

為什么睡眠如此重要？

睡眠不足會影響一切。如很難在上課時候集中注意力或影響一個人的心情。研究表明，超過20%的高中生會在上課的時候睡覺。專家也已證明缺眠會使成績下降。缺乏睡眠也會影響青少年在運動中展現自己的最佳狀態。

但是由于缺乏睡眠而引起的反應遲鈍和注意力下降并不僅僅影響到學習和運動。睡眠不足還會影響駕車人的生活。全國高速安全交通管理局估計，每年大約有1500位年齡在15—24歲之間的年輕人因為疲勞而死于車禍（駕車時睡著而發生車禍的人中有半數以上年齡在26歲以下。

傷心失落情緒低下等問題也與睡眠不足息息相關。睡眠還能通過充分放慢身體系統使還原每天消耗的體力來幫助我們保持身體健康。

如何知道自己是否已有充足睡眠？

即使你覺得自己已經睡飽了，你可能還是沒有得到充分的睡眠。如果出現以下幾種情況表明你還需要更多睡眠：

早晨很難醒來。
注意力難以集中。
上課時睡著。
心情抑郁甚至沮喪。
如何得到更多睡眠？

近來，一些研究人員，家長和老師都老師都建議中學和高中推遲早上上課時間來適應青少年更多睡眠的需要。有些學校已經開始實行。你和你的朋友，家長以及老師在學校里倡議上課時間推遲，但與此同時，你必須保證自己能適應。

以下幾件事能幫助你更好的獲得睡眠：

設定規律的就寢時間。每天晚上都在同一個時間睡覺會向你的身體發出信號“睡覺時間到了”。每天早晨在同一時間點醒來也能幫助建立睡覺模式。因此，即使在周末也要堅持這個睡覺時間表，不要晚上晚睡一小時或早晨晚起2－3個小時。

定期運動。但是不要在睡覺前運動，因為它會使你興奮更難入睡。許多睡眠專家認為，睡前5 －6小時（下午）的運動確實能助眠。

遠離刺激品。下午4點之后不要喝含有咖啡因的飲料，如蘇打水或咖啡。尼古丁也屬于刺激品，因此戒煙能讓你睡得更好。晚上喝酒也會使人休息不充分以及在夜間醒來。

放松大腦。睡前不要觀看暴力，恐怖或動作電影或電視－－這些都會使你的大腦和心跳加速。看帶有復雜或動作情節的書也會讓你睡不著或睡不好覺。
將燈低放，放松身體。燈光會向大腦發出醒來信號。遠離亮光（包括電腦屏幕），以及調輕或傾聽舒心柔和的音樂能幫助我們身體放松下來。

不要小睡過多。白天打盹超過30分鐘會使你在晚上睡得更晚。

不要通宵：不要在晚上才為重大考試作準備。因為第二天的考試而削減睡覺時間只會比你復習少但睡眠充足更糟糕。

營造正確的睡覺環境。研究表明，人們在黑暗房間那靠較涼的一邊睡得最好。關上窗戶拉上窗簾（確保窗簾能擋住亮光）。關掉房間內的暖氣（如果太冷，你可以加蓋一條毯子或傳上睡衣）。各種噪音都可能會中斷睡眠。

在光亮中醒來。清晨的亮光提醒你的身體清醒。

如果你很昏昏欲睡，你就很難讓人看出和感覺到你最好的東西。將睡眠作為你日程的一部分，你將更活潑健康