How Do I Know If I'm Getting Enough Sleep? A good way to test yourself is to figure out how long it takes you to fall asleep. If you can fall asleep in 5 to 10 minutes，you may not be getting enough sleep.If it takes 15 minutes or more， you're probably getting enough. One way to test this is to set your alarm clock to go off 10 minutes after you hit the sack¹See if you're still awake when it goes off.And if you're falling asleep during the day in classes at school， you're probably not sleeping enough.

Why Do I Need So Much Sleep? The studies found that most teens need about 9 to 9 1/2 hours of sleep to avoid behaviors associated with sleep deprivation. These behaviors include falling asleep in class，difficulty waking up in the morning，inability to concentrate， and even depression. One study found that sleep may have a significant affect on grades—— teens who got the least amount of sleep earned Cs and Ds， whereas teens who got the most sleep tended to get As and Bs. Unfortunately， many surveys show that the average teen only gets about 6 or 7 hours of sleep each night，and 20% of all high school students report falling asleep in school.

In addition to the fact that getting enough sleep may help your grades，sleep helps keep you healthy by slowing your metabolism²， heartbeat， and respiration³ enough to re-energize you after everyday physical activities.It has also been found that sleep releases a growth hormone that helps tissues grow properly，forms red blood cells thatdeliveroxygen⁴to your brain，and promotes bone growth.

Trytakingthese simple steps to get more sleep each night:

★Don't drink bever ages with caffeine⁵，such as soda and coffee， after 4 PM.★Don't watch violent or scary⁶ television shows or movies or read books that might keep you from falling asleep.★ Don't nap excessively.More than 30 minutes may keep you from falling asleep later. ★ Don't wait until the night before a big test to study.Staying up all night can really mess up your sleep patterns.★Don't use a computer right before bed. Light signals to your brain that it's time to wake up. Do exercise regularly， but not right before bed.★Do try to go to bed and wake up at the same time every day.★Do get into bright light in the morning to help wake you up. ★ Do keep the lights low in the evening to help you unwind⁷ from the day. Al so try meditating⁸， reading， or listening to soothing music.★ Do try to stick with your regular sleep schedule on weekends， too. You can't catch up on missed sleep from the week before.

如何知道自己的睡眠是充足的?自我檢驗(yàn)的一種好方法就是算一算你要多長時(shí)間才能睡著。如果在5-10分鐘內(nèi)睡著，你就有可能睡眠不足。如果用15分鐘或更長的時(shí)間，你大概有充足的睡眠。有一個(gè)辦法可以用來對此進(jìn)行測試，即在上床睡覺之后把鬧鐘鈴聲定在10分鐘之后。鈴聲響起的時(shí)候，看看自己是否還醒著。此外，如果你白天上課的時(shí)候睡著了，也很有可能是睡得不夠的原因。

為什么我要睡這么長時(shí)間?有研究表明，絕大部分的青少年需要睡9-9.5小時(shí)才能避免出現(xiàn)與睡眠不足有關(guān)的行為。這些行為包括在課堂上睡覺、早上醒不了、不能集中注意力，甚至是萎靡不振。一項(xiàng)研究發(fā)現(xiàn)，睡眠對考試成績的影響很大：睡眠不足的青少年成績平平或是勉強(qiáng)及格，而睡眠充足的青少年則成績良好或優(yōu)秀。令人遺憾的是，許多調(diào)查顯示青少年一般每晚只睡6-7個(gè)小時(shí)，有20％的中學(xué)生稱他們有過在學(xué)校睡覺的情況，充足的睡眠不僅有助于提高學(xué)習(xí)成績，還能通過延緩新陳代謝，降低心跳和呼吸的頻率，使人們在每天的體力活動(dòng)之后恢復(fù)精力。它還可以釋放有助于人體組織允分發(fā)育的生長激素，生成向大腦運(yùn)輸氧的紅血球并促進(jìn)骨骼生長。

下列這些簡單易行的方法會(huì)讓你每晚的睡眠更充足。

◎不要在下午4點(diǎn)以后喝含有咖啡因的飲料，如蘇打水和咖啡?！虿灰从斜┝涂植纼?nèi)容的電視節(jié)目、電影或書籍，它們會(huì)讓你無法入眠。不要長時(shí)間地打盹。打盹時(shí)間超過30分鐘可能會(huì)使你晚上睡不著。◎不要拖到臨近大考才學(xué)習(xí)。整宿的熬夜確實(shí)會(huì)打亂你的睡眠習(xí)慣?！虿灰R睡前用電腦。光線給大腦發(fā)出的信號使其誤認(rèn)為起床的時(shí)間到了。◎定期鍛煉身體，但不是在臨睡前?！虮M量每天按時(shí)睡覺和起床?！?要習(xí)慣清晨明亮的光線，它也能喚醒你。◎晚上把燈光調(diào)得柔和些，這樣有助于從一天的疲憊中放松下來。也可以試著沉思、看書或是聽些柔和的音樂。◎周末也要堅(jiān)持按時(shí)起居。別指望把上一周缺的覺這一周補(bǔ)回來。

注釋：

1．sackn．[美俚]床hit the~[美俚]上床睡覺 2．metabolismn．新陳代謝(作用)

3．respirationn．呼吸 4．oxygen n．[化]氧，氧氣

5．caffeinen．[化]咖啡因 6．scary adj．[口]引起驚慌的，駭人的

7. unwind vt．使松馳，使不緊張8．meditate vi.沉思