Power Napping is Good for the I.Q.
Today we hear more and more about the importance of getting enough sleep—about eight hours a night. Sleep can help heal and give energy to both the body and the brain. ____1____ It seems almost certain that the third of our lives that we spend asleep has a great effect on the two-thirds that we are awake. Sleep affects our emotions, memory, focus, and behavior.
Studies show that people in developed countries spend less time asleep and more time at work or commuting. Dr. Karine Spiegel, at the University of Chicago, has found that the average length of sleep has gone down from nine hours a night in 1910 to seven-and-a-half hours a night today. However, our bodies cannot function well without enough sleep. ____2____ According to Canadian scientist Dr. Stanley Coren, every hour of lost sleep at night causes us to lose one I.Q. point the next day. For example, when someone gets only five or six hours of sleep each night for a week, the person’s I.Q. could go down 15 points or more. ____3____
Most sleep experts say that humans need at least eight hours of sleep every day, but it should be in two stages: a long sleep at night and a shorter nap in the afternoon. Some companies help their employees follow this advice. ____4____ They say this makes the workers much more efficient.
To study sleep deprivation (not getting enough sleep), scientists use a test called the Multiple Sleep Latency Test (MSLT). During the test, a person stays in a darkened, quiet room during the daytime. Scientists believe that a sleep-deprived person will fall asleep quickly. If it takes ten minutes or longer to fall asleep, the person is probably getting enough sleep.
Scientists have also found that the time of year seems to affect how much sleep we need. ____5____ However, in the summer, people sometimes sleep as little as six hours, without having any problems.
练习：
A They allow them to “power nap” in the afternoon, if only for 20 minutes.
B Losing just one or two hours of sleep a night, over a long period of time, can cause serious health problems.
C People usually sleep longer in the winter, sometimes as much as 14 hours a night.
D People in power are more intelligent because they take naps.
E Medical experts now believe that sleep is even more important for health than diet or exercise.
F That’s why, without enough sleep, a normally intelligent person may start to have difficulty doing daily tasks.
答案与题解：
1.E 本题的做题线索为其之前的一句话，即“睡眠能有助于恢复补充身体和大脑的能量”，其描述的是睡眠的功能，选项E说的也是睡眠的功能，与前文形成补充说明。
2.B 该选项对睡眠减少的后果进行了描述，与前一句中“在缺少足够睡眠的情况下，我们的身体无法正常运作”形成呼应，是一个结果性的解释，虽然选项F也是对睡眠不足人群后果的解释，但是选项F在此不符合上面一句话的语境，其主要是在描述睡眠和智商直接的关系，在下文才有所提及，故答案为选项
3.F 从第三段最后一句话看出，选项F描述的是睡眠和智商之间的联系，其做题线索和上一题一样，都是对前面一句话的结果性补充描写。
4.A 该题的做题线索也是对其前一句的话的补充说明，前文中提到了一些公司在睡眠方面对其员工进行了帮助，该选项则简短介绍了这些公司都采取了哪些具体方案。
5.C 本题的做题线索为上下文搭配，在最后一段的第一句中明显提及了睡眠和一年中的不同时期有关，后面最后一句话又讲到了夏季的睡眠时间，那么从中可以判断出，这里描述的应该是另外一种季节的睡眠时间，从而与段首观点句呼应并与下句形成对比，而选项C描述的便是冬季的睡眠时间，故符合要求。
