For millions of years before the appearance of the electric light, shift work, all-night cable TV and the Internet, the Earth's creatures evolved on a planet with predictable and reassuring 24-hour rhythms. Our biological clocks are set for this daily cycle. Simply put, 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 hours 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 sleeping in, by traveling frequently between time zones 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(座右铭)is 'Sleep defensivejy'," 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 Elaner, who used to suffer from sleeplessness, a few lifestyle changes—avoiding stimulants and late meals, exercising hours before bedtime, relaxing with a hot bath—yield better sleep.
单选题
What is TRUE of human sleep?
【正确答案】
C
【答案解析】解析：文章第一段提到：“Contrary to popular belief，humans don’t need less sleep as they age．”可见人所需的睡眠并不会因为年龄的增加而减少，所以A项不对。文中还提到了大部分的男人和女人一个晚上需要8～8．5小时的睡眠，而不是7．5小时。所以B项不对。文章第二段“But on average，Americans sleep only about seven and a half hours per night，a marked drop from the nine hours they averaged in 1910．”可见美国人现在每晚平均睡眠只有7．5小时，比起1910年的平均睡眠9小时时间是明显少了。所以C项正确。D项的内容与文章所说的意思相反，对于大多数人来说，通常加夜班时，不到6小时的睡眠是远远不够的，所以D项不对。因此本题的正确答案为C。
单选题
For our bodies to function properly, we should______.
【正确答案】
A
【答案解析】解析：在文章第一段中已经指出了：“Most women and men need between eight and eight and a half hours of sleep a night to function properly throughout their lives．”大部分的男人和女人一个晚上需要8～8．5小时的睡眠才能安全地度过一生。可见，如果我们的身体要正常运行，我们应该每晚至少睡8小时。A项的意思与原文相符相符。B项的意思与原文相反，D项的内容与原文不符，C项的内容在文章中没有提及。所以本题的正确答案应该是A。
单选题
According to the author, many sleeping disorders are caused by______.
【正确答案】
C
【答案解析】解析：文章第四段中讲到：“Sleep experts say that most people would benefit from a good look at their sleep patterns．”睡眠专家说。通过认真观察自己的睡眠模式，大多数人可以受益。可见，作者认为，许多睡眠紊乱症是由不恰当的睡眠模式导致的。所以C项正确。第三段讲到“睡眠紊乱症常常被诊断为其他病症”，所以A项不对；文章最后一段最后一句话讲到，睡前锻炼等习惯对睡H民有很好的效果，所以B项不对；第三段中讲到“在被转介给琼斯医生的那些可能患有慢性疲劳综合征的病人中，约1／3的人实际上患的是可治疗的睡眠紊乱症”，这两者之间并不是因果的关系，所以D项也不对。因此本题应该选C。
单选题
Which of the following measures can help you sleep better?
【正确答案】
B
【答案解析】解析：文章第四段中讲到：“As with Elaner，who used to suffer from sleeplessness，a few lifestyle changes--avoiding stimulants and late meals，exercising hours before bedtime，relaxing with a hot bath--yield better sleep．”可见吃刺激性食物和夜宵都是对睡眠不利的。洗热水澡能帮助更好地睡眠。所以A和C不对，B正确。文章第三段：“But many problems are caused by staying up late and sleeping in，by traveling frequently between time zones or by working nights．”许多睡眠紊乱症是由于在不同的时区频繁旅行或上夜班睡得太晚和睡过了头而引起的。可见在不同的时区旅行也是不利睡眠的。所以D不对。因此本题应该选B。
单选题
"Sleep defensively" means that______.
【正确答案】
C
【答案解析】解析：文章第四段“My motto 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．玛丽·卡斯克顿说，我的座右铭是“保护性地睡眠”。她说，人们需要留出足够的时间睡眠，即使这意味着放弃其他事情。可见，Sleep defensively指人们有必要时应该为了留出足够的时间睡眠而放弃其他事情。所以C项正确。A项明显不对；B、D项两项所表达的意思与文章内容无关。所以这里应该选C。