For millions of years before the appearance of the electric light，shift work，all-night cable TV and the Internet，earth’s creatures evolved on a planet with predictable and reassuring 24-hour rhythms. Our biological clocks are set for this daily cycle. Simply，our bodies want to sleep at night and be awake during the day. Most women and men need between eight and eight and a half hours of sleep a night to function properly throughout their lives.(Contrary to popular belief，humans don’t need less sleep as they age.)

　　But on average，Americans sleep only about seven and a half hour per night，a marked drop from the nine hours they averaged in 1910. What’s worse，nearly one third of all Americans get less than six hours of sleep on a typical work night. For most people，that’s not nearly enough.

　　Finding ways to get more and better sleep can be a challenge. Scientists have identified more than 80 different sleep disorders. Some sleeping disorders are genetic. But many problems are caused by staying up late and by traveling frequently between time zone or by working nights. Dr. James F. Jones at National Jewish Medical and Research Center in Denver says that sleep disorders are often diagnosed as other discomforts. About one third of the patients referred to him with possible chronic fatigue syndrome actually have treatable sleep disorders.“Before we do anything else，we look at their sleep.”Jones says.

　　Sleep experts say that most people would benefit from a good look at their sleep patterns.“My motto(座右銘)is‘Sleep defensively’.”says Mary Carskadon of Brown University. She says people need to carve out sufficient time to sleep，even if it means giving up other things. Sleep routines-like going to bed and getting up at the same time every day-are important. Pre-bedtime activities also make a difference. As with Elsner，who used to suffer from sleeplessness，a few life style changes—avoiding stimulants and late meals，exercising hours before bedtime，relaxing with a hot bath—yield better sleep.

　　41. What is TRUE of human sleep?

　　A. On average，people in the U. S. today sleep less per night than they used to.

　　B. For most people，less than six hours of sleep on a typical work night is enough.

　　C. Most people need less sleep when they grow older.

　　D. Most people need seven and a half hems of sleep every night.

　　42. For our bodies to function properly，we should　　　　.

　　A. adjust our activities to the new inventions

　　B. be able to predict the rhythms of our biological clocks

　　C. sleep for at least eight hours per night

　　D. believe that we need less sleep as we age

　　43. According to the author，many sleeping disorders are caused by　　　　.

　　A. improper sleep patterns

　　B. chronic fatigue syndrome

　　C. other diseases

　　D. pre-bedtime exercises

　　44. Which of the following measures can help you sleep better?

　　A. Having late meals.

　　B. Traveling between time zones.

　　C. Staying up late.

　　D. Taking a hot bath.

　　45. “Sleep defensively”means that　　　　.

　　A. people should sacrifice other things to getting enough sleep if necessary

　　B. people should give up going to bed and getting up at the same time every day

　　C. people should go to a doctor and have their problems diagnosed

　　D. people should exercise immediately before going to bed every night

　　答案解析：

　　在電燈、輪換工作、通宵有線電視和因特網(wǎng)出現(xiàn)之前的數(shù)百萬(wàn)年里，地球上的生物以可預(yù)言的、確定的24小時(shí)節(jié)奏演變進(jìn)化著。我們的生物鐘就是為這樣的日常循環(huán)而設(shè)置的。簡(jiǎn)單地說(shuō)，我們的身體需要在夜晚休息，白天清醒。大多數(shù)男女每天晚上需要八到八個(gè)半小時(shí)的休息時(shí)間以保證使他們的生活正常進(jìn)行(與流行的觀念相反，人并不是變老以后需要的睡眠就減少了)。

　　但是，美國(guó)人平均每晚的睡眠時(shí)間只有大約七個(gè)半小時(shí)，比1910年的平均九小時(shí)時(shí)間大大減少了，更糟的是，在典型的加班夜，幾乎有1/3的美國(guó)人只有不到六個(gè)小時(shí)的睡眠時(shí)間。對(duì)于大多數(shù)人來(lái)說(shuō)，那是遠(yuǎn)遠(yuǎn)不夠的。

　　找到能夠睡得更長(zhǎng)、更好的方法可能是個(gè)挑戰(zhàn)。科學(xué)家已經(jīng)分辨出超過(guò)80種不同的睡眠紊亂癥。有些睡眠紊亂癥是遺傳的。但是，許多問(wèn)題是由于睡得太晚或經(jīng)常在不同時(shí)差的地區(qū)之間旅行或上夜班導(dǎo)致的。在丹佛市國(guó)家猶太人醫(yī)學(xué)和研究中心工作的詹姆斯·艾福·瓊斯醫(yī)生說(shuō)，睡眠紊亂癥常常被診斷為其他不適癥。在他的那些可能患有慢性疲勞綜合征的病人中，有1/3的人實(shí)際上患的是可治療睡眠紊亂癥。瓊斯說(shuō)：“在我們做任何其他事情之前，我們要先看一下他們的睡眠情況。”

　　睡眠專家說(shuō)，大多數(shù)人可以從仔細(xì)觀察自己的睡眠姿勢(shì)中受益。布朗大學(xué)的瑪麗卡斯克頓說(shuō)：“我的座右銘是‘保護(hù)性地睡眠’。”人們需要足夠的時(shí)間來(lái)睡覺，即使這意味著要放棄其他事情。睡眠安排，比如每天在相同的時(shí)間睡覺、起床非常重要。睡前的活動(dòng)也會(huì)帶來(lái)不同的影響。如以前遭受過(guò)失眠困擾的艾拉勒，改變了一些生活習(xí)慣，避免刺激性食物和吃夜宵，睡覺前運(yùn)動(dòng)幾小時(shí)，洗個(gè)熱水澡放松一下就會(huì)獲得很好的睡眠。

　　41.正確答案:A

　　解析:關(guān)于人類睡眠下面哪句是對(duì)的?

　　A.一般來(lái)講，今天美國(guó)人睡的時(shí)間比他們過(guò)去要少。

　　B.對(duì)大多數(shù)人來(lái)說(shuō)，一個(gè)典型的加班工作少于6小時(shí)的睡眠是足夠的。

　　C.大多數(shù)人的年齡越大，需要的睡眠越少。

　　D.大多數(shù)人每晚需要七個(gè)半小時(shí)的睡眠。

　　線索：文章的第2段提到“But on average，Americans sleep only about seven and a half hour per night，a marked drop from the nine hours they averaged in 1910.”表明A是正確答案。B選項(xiàng)和原文的內(nèi)容相反“...get less than six hours of sleep on a typical work night. For most people，that’s not nearly enough.”C選項(xiàng)和文章的整個(gè)內(nèi)容不符合。D選項(xiàng)和原文“Most women and men need between eight and eight and a half hours of sleep a night to function properly”不符合。

　　42.正確答案:C

　　解析:為了使我們的身體功能正常運(yùn)行，我們應(yīng)該　　　　。

　　A.調(diào)整我們的活動(dòng)以適應(yīng)新的發(fā)明

　　B.能夠預(yù)測(cè)到我們生物鐘的節(jié)奏

　　C.每晚睡至少8小時(shí)

　　D.相信隨著我們的年齡增大，我們需要的睡眠更少

　　線索：文章的第1段提到“Most women and men need between eight and eight and a half hours of sleep a night to function properly throughout their lives.”表明選項(xiàng)C是正確答案。D選項(xiàng)的內(nèi)容和原文截然相反“Contrary to popular belief，humans don’t need less sleep as they age.”與流行的觀念相反，人并不是變老以后就需要減少睡眠。

　　43.正確答案:A

　　解析:根據(jù)作者，許多睡眠紊亂出現(xiàn)的原因是　　　　。

　　A.不正常的睡眠姿勢(shì)

　　B.慢性疲勞綜合征

　　C.其他的疾病

　　D.睡前的鍛煉

　　線索：文章的第3段提到“But many problems are caused by staying up late and by traveling frequently between time zone or by working nights.”說(shuō)明選項(xiàng)A是正確答案。B選項(xiàng)不是問(wèn)題出現(xiàn)的原因，可以認(rèn)為是它的一個(gè)并發(fā)癥。D選項(xiàng)是改進(jìn)睡眠的一個(gè)方法，不是問(wèn)題產(chǎn)生的一個(gè)原因。

　　44.　答案:D

　　解析:下面的哪一個(gè)措施能幫助你睡得更好?

　　A.吃夜宵。

　　B.在時(shí)區(qū)之間旅行。

　　C.睡得很晚。

　　D.洗一個(gè)熱水澡。

　　線索：文章的第4段提到“avoiding stimulants and late meals，exercising hours before bedtime，relaxing with a hot bath—yield better sleep.”選項(xiàng)D是正確答案。其他幾個(gè)選項(xiàng)是造成失眠的原因，不是減輕失眠的方法。

　　45.答案:A

　　解析:“保護(hù)性睡眠”意思是　　　　。

　　A.如果有必要，人們應(yīng)該犧牲別的事情去獲得足夠的睡眠

　　B.人們應(yīng)該放棄“每天在相同的時(shí)間睡覺、起床”的念頭

　　C.人們應(yīng)該去看醫(yī)生并且診斷自己的病癥

　　D.在每晚睡覺之前人們應(yīng)該立即鍛