The beginning of our sleep-deficit (睡眠不足) crisis can be traced to the invention of the light bulb a century ago. From diary entries and other personal accounts from the 18th and 19th centuries, sleep scientists have reached the conclusion that the average person used to sleep about 9.5 hours a night. “The best sleep habits once were forced on us, when we had nothing to do in the evening down on the farm, and it was dark.” By the 1950s and 1960s, that sleep schedule had been reduced dramatically, to between 7.5 and eight hours, and most people had to wake to an alarm clock. “People cheat on their sleep, and they don't even realize they're doing it,” says Dr. David. “They think they're okey because they can get by on 6.5 hours, when they really need 7.5, eight or even more to feel ideally vigorous.”
Perhaps the most merciless robber of sleep, researchers say, is the complexity of the day. Whenever pressures from work, family, friends and community mount, many people consider sleep the least expensive item on his programme. “In our society, you're considered dynamic if you say you only need 5.5 hours' sleep. If you've got to get 8.5 hours, people think you lack drive and ambition.”
To determine the consequences of sleep deficit, researchers have put subjects through a set of psychological and performance tests requiring them, for instance, to add columns of numbers or recall a passage read to them only minutes earlier. “We've found that if you're in sleep deficit, performance suffers,” says Dr.David. “Short-term memory is weakened, as are abilities to make decisions and to concentrate.”
31. People in the 18th and 19th centuries used to sleep about 9.5 hours a night because they had .
A) no electric lighting C) the best sleep habits
B) no drive and ambition D) nothing to do in the evening
32. According to Dr. David, Americans .
A) are ideally vigorous even under the pressure of life
B) can get by on 6.5 hours of sleep
C) do not know how to relax themselves properly
D) often neglect the consequences of sleep deficit
33. Many Americans believe that .
A) they need more sleep to cope with the complexities of everyday life
B) sleep is the first thing that can be sacrificed when one is busy
C) to sleep is something one can do at any time of the day
D) enough sleep promotes people's drive and ambition
34. The word “subjects”(Para. 4, Line 1) refers to .
A) the psychological consequences of sleep deficit
B) special branches of knowledge that are being studied
C) people whose behavior or reactions are being studied;
D) the psychological consequences of sleep definit
35. It can be concluded from the passage that one should sleep as many hours as is necessary to .
A) maintain one's daily schedule C) feel energetic and perform adequately
B) improve one's memory dramatically D) be considered dynamic by other people
Questions 36 to 40 are based on the following passage:
The concept of personal choice in relation to health behaviors is an important one. An estimated 90 percent of all illnesses may be preventable if individuals would make sound personal health choices based upon current medical knowledge. We all enjoy our freedom of choice and do not like to see it restricted when it is within the legal and moral boundaries of society. The structure of American society allows us to make almost all our own personal decisions that may concern our health. If we so desire, we can smoke, drink excessively, refuse to wear seat belts, eat whatever foods we want, and live a completely sedentary life-style without any exercise. The freedom to make such personal decisions is a fundamental aspect of our society, although the wisdom of these decisions can be questioned. Personal choices relative to health often cause a difficulty. As one example, a teenager may know the facts relative to smoking cigarettes and health but may be pressured by friends into believing it is the socially accepted thing to do.
