Why is it so difficult to fall asleep when you are overtired?There is no one answer that applies to every person. But many people fail to note the distinction between tiredness—physical tiredness—and sleepiness， the inability to stay awake. It’s possible to feel“tired”physically and still be unable to fall asleep， because while your body may be tired， you don’t feel sleepy. To fall asleep， you need adequate time to unwind， even if you feel fatigued. It’s not so easy to simply“turn off”.

According to Carl E. Hunt， director of the National Center on Sleep Disorders Research in Bethesda， Maryland， most people do not allow themselves enough deceleration(減緩).

Lack of sleep makes matters even more complex. Experts say adults need at least 7 to 8 hours of sleep a night to function properly. When you get less sleep than that on continuous nights， you begin to increase“sleep debt”. As sleep debt increases(and functionality decreases)， your body experiences a stress response and begins to release(釋放)adrenaline(=adrenalin[生化]腎上腺素). Now a cruel cycle has been created: You experience the feeling of being more and more tired， but your body is increasingly stimulated(促進(jìn)，刺激).“Power sleeping”for more hours on weekends is only a temporary solution.“There is no substitute for getting a good night’s sleep on a regular basis，”says Hunt.

Most of us， however， don’t get the sleep we need. According to the 2002 National Sleep Foundation， Americans sleep an average of 6.9 hours per night during the week， and 58 percent of adults experience symptoms of insomnia(失眠癥)a few nights a week or more.

1. According to the passage， which of the following is true?

A. Many people didn’t fail to note the distinction between fatigue and sleeping.

B. You can probably feel tired physically and mentally and still be unable to fall asleep.

C. Even if you feel fatigued， in order to fall asleep you need enough time to relax yourself.

D. When you are overtired， you will fall asleep very easily.

2. Why did the author say “l(fā)ack of sleep makes matters even more”?

A. Because lack of sleep makes you unable to do everything.

B. Because lack of sleep causes a sleep debt. As sleep debt increases， your body experiences a stress response and begin to release adrenaline.

C. You experience the feeling of being more and more tired， your body is decreasedly stimulated.

D. To function properly， adults need at least 7 to 8 hours of sleep a day.

3. The word “substitute” underlined in the third paragraph most probably means______.

A. chanceB. problemC. senseD. replacement

4. What’s the best title for this passage?

A. The relationships between physical tiredness and sleepness.

B. Most people don’t allow themselves sufficient deceleration.

C. Lack of sleep makes matters even more.

D. Why is it so difficult to fall asleep when you are overtired?

5. What have you learned from the passage?

A. It’s easy for us to fall asleep when we are very tired.

B. Most of us don’t get enough sleep because we are too busy.

C. We can’t live without sleep.

D. To function properly，everyone needs enough sleep every day.

答案解析

1. C。細(xì)節(jié)判斷題。從文章第一段第四句開(kāi)始就可以得到此答案。選項(xiàng)A與文章首段第三句不符;選項(xiàng)B與文章首段“It’s possibly to feel‘tired’ physically and still be unable to fall asleep”不符。選項(xiàng)D與文章“It’s not so easy to simply ‘turn off’”不符。

2. B。細(xì)節(jié)理解題。在文章第三段，專(zhuān)家說(shuō)成年人為了身體機(jī)能正常運(yùn)轉(zhuǎn)每晚至少需要7～8個(gè)小時(shí)的睡眠，如果睡眠不足，就會(huì)背上“睡眠債”，當(dāng)睡眠債越積越多(同時(shí)身體機(jī)能減弱)，你的身體將會(huì)做出壓力反應(yīng)，開(kāi)始釋放腺素。而A、C、D項(xiàng)均與原文內(nèi)容不符。

3. D。詞義猜測(cè)題。上面已讀到由于睡眠嚴(yán)重不足而引發(fā)了一個(gè)惡性循環(huán)，你感覺(jué)越來(lái)越累，你的身體受到的刺激卻越來(lái)越強(qiáng)，即使猛補(bǔ)上幾個(gè)小時(shí)也只是權(quán)宜之計(jì)。而要有規(guī)律地每晚睡上一個(gè)好覺(jué)，這是任何東西都代替不了的。replacement“替代物，代替者”與畫(huà)線(xiàn)詞substitute意義相近。

4. D。文章主旨判斷題。瀏覽全文，不難看出，全文討論的中心就是當(dāng)你過(guò)度疲勞時(shí)你為何難以入睡。文章一開(kāi)始就提出此論點(diǎn)，然后展開(kāi)說(shuō)明。

首段的基本大意是:To fall asleep，you need adequate time to unwind， even if you feel fatigued.

第二段講的是專(zhuān)家認(rèn)為:Most people don’t allow themselves sufficient deceleration.

第三段講的是:Lack of sleep makes matters even more.

第四段講的是:Most of us， however， don’t get the sleep we need.

5. D。邏輯推理題，全文中心談的就是一個(gè)人若疲勞就很難入睡，而難以入睡就會(huì)導(dǎo)致身體機(jī)能不能正常運(yùn)轉(zhuǎn)。只有保證好的休息，才能有好的工作狀態(tài)。選項(xiàng)A、B、C均不符合原文內(nèi)容。

編輯/梁宇清