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(duì)于大多數(shù)青少年來(lái)說(shuō)，8.5-9個(gè)小時(shí)的睡眠是必需的。適量的睡眠是保證大家考試能正常發(fā)揮，運(yùn)動(dòng)能不絆到腳的關(guān)鍵。但可惜的是，許多青少年都沒(méi)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(lái)，人們都會(huì)指責(zé)青少年晚上睡的太晚，上學(xué)睡過(guò)頭以及上課時(shí)間睡覺(jué)。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(zhì)區(qū)別。

這些研究指出，在青春期期間，青少年身體的24小時(shí)生理節(jié)奏（有點(diǎn)類似體內(nèi)的生物鐘）被臨時(shí)重置， 從而導(dǎo)致青少年睡的更晚，醒的更遲。24小時(shí)生理節(jié)奏的改變可能是由于青少年在夜間產(chǎn)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(nèi)24小時(shí)生理節(jié)奏的改變與我們?cè)谳^忙碌時(shí)期的改變一致。大多數(shù)的青少年都承受著比自己幼年時(shí)期更大更緊張的學(xué)習(xí)壓力，且他們只有通過(guò)更努力學(xué)習(xí)才能克服這些壓力。同時(shí)，青少年還有其他時(shí)間上的要求---運(yùn)動(dòng)，一些課外活動(dòng)，以及為了上大學(xué)攢錢而做兼職，等等。

某些學(xué)校較早的上課時(shí)間可能也是導(dǎo)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(xué)，這就意味著他們一天只能擠出6-7個(gè)小時(shí)睡覺(jué)。一個(gè)晚上少幾個(gè)小時(shí)的睡眠不會(huì)產(chǎn)生什么大問(wèn)題，但是長(zhǎng)期少眠就會(huì)造成嚴(yán)重的睡眠不足。

為什么睡眠如此重要？

睡眠不足會(huì)影響一切。如很難在上課時(shí)候集中注意力或影響一個(gè)人的心情。研究表明，超過(guò)20%的高中生會(huì)在上課的時(shí)候睡覺(jué)。專家也已證明缺眠會(huì)使成績(jī)下降。缺乏睡眠也會(huì)影響青少年在運(yùn)動(dòng)中展現(xiàn)自己的最佳狀態(tài)。

但是由于缺乏睡眠而引起的反應(yīng)遲鈍和注意力下降并不僅僅影響到學(xué)習(xí)和運(yùn)動(dòng)。睡眠不足還會(huì)影響駕車人的生活。全國(guó)高速安全交通管理局估計(jì)，每年大約有1500位年齡在15—24歲之間的年輕人因?yàn)槠�勞而死于車禍（駕車時(shí)睡著而發(fā)生車禍的人中有半數(shù)以上年齡在26歲以下。

傷心失落情緒低下等問(wèn)題也與睡眠不足息息相關(guān)。睡眠還能通過(guò)充分放慢身體系統(tǒng)使還原每天消耗的體力來(lái)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(jué)得自己已經(jīng)睡飽了，你可能還是沒(méi)有得到充分的睡眠。如果出現(xiàn)以下幾種情況表明你還需要更多睡眠：

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

近來(lái)，一些研究人員，家長(zhǎng)和老師都老師都建議中學(xué)和高中推遲早上上課時(shí)間來(lái)適應(yīng)青少年更多睡眠的需要。有些學(xué)校已經(jīng)開(kāi)始實(shí)行。你和你的朋友，家長(zhǎng)以及老師在學(xué)校里倡議上課時(shí)間推遲，但與此同時(shí)，你必須保證自己能適應(yīng)。

以下幾件事能幫助你更好的獲得睡眠：

設(shè)定規(guī)律的就寢時(shí)間。每天晚上都在同一個(gè)時(shí)間睡覺(jué)會(huì)向你的身體發(fā)出信號(hào)“睡覺(jué)時(shí)間到了”。每天早晨在同一時(shí)間點(diǎn)醒來(lái)也能幫助建立睡覺(jué)模式。因此，即使在周末也要堅(jiān)持這個(gè)睡覺(jué)時(shí)間表，不要晚上晚睡一小時(shí)或早晨晚起2－3個(gè)小時(shí)。

定期運(yùn)動(dòng)。但是不要在睡覺(jué)前運(yùn)動(dòng)，因?yàn)樗鼤?huì)使你興奮更難入睡。許多睡眠專家認(rèn)為，睡前5 －6小時(shí)（下午）的運(yùn)動(dòng)確實(shí)能助眠。

遠(yuǎn)離刺激品。下午4點(diǎn)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(huì)使人休息不充分以及在夜間醒來(lái)。

放松大腦。睡前不要觀看暴力，恐怖或動(dòng)作電影或電視－－這些都會(huì)使你的大腦和心跳加速�？磶в袕�(fù)雜或動(dòng)作情節(jié)的書(shū)也會(huì)讓你睡不著或睡不好覺(jué)。
將燈低放，放松身體。燈光會(huì)向大腦發(fā)出醒來(lái)信號(hào)。遠(yuǎn)離亮光（包括電腦屏幕），以及調(diào)輕或傾聽(tīng)舒心柔和的音樂(lè)能幫助我們身體放松下來(lái)。

不要小睡過(guò)多。白天打盹超過(guò)30分鐘會(huì)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(zhǔn)備。因?yàn)榈诙�天的考試而削減睡覺(jué)時(shí)間只會(huì)比你復(fù)習(xí)少但睡眠充足更糟糕。

營(yíng)造正確的睡覺(jué)環(huán)境。研究表明，人們?cè)诤诎捣块g那靠較涼的一邊睡得最好。關(guān)上窗戶拉上窗簾（確保窗簾能擋住亮光）。關(guān)掉房間內(nèi)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(huì)中斷睡眠。

在光亮中醒來(lái)。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(jué)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