Judging from recent surveys, most experts in sleep behaviour agree that there is an epidemic (流行病) of sleepiness in the nation. “I can’t think of a single study that hasn’t found Americans getting less sleep
than they ought to,” says Dr. David. Even people who think they are sleeping enough would probably be
better off with more rest.
     The beginning of our sleep-lack crises can be traced back to the invention of the light bulb a century
ago. From diary entries and our 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 on the farm, and it was dark.” By the 1950s and 1960s, the sleep schedule had been reduced dramatically, to between 7.5 and 8 hours, and most people had to wake to an alarm clock. “People cheat in their sleep, and they don’t even realize
they’re doing it,” says Dr. David. “They think they’re okay because they can manage with 6.5 hours, when they really need 7.5, 8 or even more to feel ideally energetic.”
      Perhaps the most cruel robber of sleep, researches say, is the complexity of the day. Whenever
pressures from work, family, friends and community increase, many people consider sleep the least
expensive item on their programme. “In our society, you’re considered energetic if you say you need only 5.5 hours’ sleep. If you have to get 8.5 hours, people think you lack drive and ambition.”
     To determine the consequences of sleep-lack, 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 lacking in sleep, performance
suffers,” says Dr. David. “Short-term memory is weakened, so are abilities to make decisions and to
concentrate.”

1. What is the main topic of the passage?

A. Research on the causes and consequences of sleep-lack.
B. The epidemic of sleepiness in the modern times.
C. The history of people’s sleeping patterns.
D. The minimum of our sleeping hours.

2. Which of the following is Dr. David’s opinion?
A. People who think they are sleeping enough are better off than those who don’t.
B. Some people can remain energetic with only 6.5 hours’ sleep a night.
C. If they get 8.5 hours’ sleep, people will be full of drive and ambition.
D. People’s performance becomes worse if they are lacking in sleep.

3. People in the 18th and 19th centuries slept about 9.5 hours a night because __________.

A. they were forced by their parents to do so
B. they knew what was best for their health
C. they had no electricity
D. they were not so energetic and ambitious as modern people are

4. The major cause of sleep-lack of modern people is _______.

A. the endless TV programmes in the evenings and on the Internet
B. the heavy work load of the day
C. the enough energy modern people usually have
D. loud noises in the modern cities

5. What does the word “subject” in paragraph 4 mean?

A. Person or thing that is being discussed or described.
B. Branch of knowledge studied in a school.
C. Person or thing being treated in a certain way or being experimented on.
D. Any member of a State apart from the supreme ruler.