A、One half. B、Two fifths. C、One quarter. D、10% to 15% . D本题设题点在数字处。根据句(2)可知，国家卫生研究所提到，总人口中有10％到15％的人患有慢性失眠症，因此[D]为答案。

Interviewer(M) Dr. Joanne Getsy(W)
Now, listen to Part One of the interview.
M: Another sleepless night... This morning on Today’s Health: run-down America. With the hassles of life and other tough hours in the day, more and more people are getting by on less and less sleep. What can you do to get more effective rest? Joining us now is Dr. Joanne Getsy, medical director of the Drexel sleep center. Dr. Getsy, welcome!
W: Good morning!
M: Good to have you here. We talk about insomnious people who can’t seem to get to sleep. But there are also some people, including me, who just don’t sleep because we’re just too busy. I meant to go to bed at nine last night. It was 22:30 before I climbed into bed. So how do you separate the two?
W: Oh, I think most people who complain of trouble sleeping are really in your category.(1-1) There is just the 24-hour world, but we have too much to do, so there is just not enough time for sleep. And I think the important thing is that people don’t understand the importance of sleep. You know, we exercise and we eat right and we try to do what is right for us. But we forget that sleep is as important as all of those things.
M:(1-2) It is not a luxury, but something about health. Many people don’t realize that, however.(2) The National Institute of Health says 10% to 15% of the general population struggles with chronic insomnia. And some of those people do fall in the category that they can’t sleep, as much as they try.
W: That’s right! And when we see them at sleep specialists, we can usually determine from what they tell us, whether they really have insomnia and have trouble sleeping, from a true sleep disorder or whether they just can’t seem to find the time for sleep.
M: Alright.(3-1) Primary insomnia, again, is people who can’t sleep enough because of the health condition. But they simply can’t get to sleep. You have got some advice for them, including " To stay asleep, you must stay awake. "
W:(3-2) Yes! The important thing is to keep a schedule.(4) People who have trouble sleeping really need to keep the schedule where they schedule when their sleep is going to be. We must try to find the time when we’re going to be asleep and the time when we must stay awake.
M:(5-1) Even in fact I’m not tired until 3 a. m. ?
W:(5-2) Then you go to bed at 3 a. m.
M:(5-3) Go to bed at 3 a. m. ? And then get up and go to work at 7 or 8 a. m. ?
W: Exactly! We make a schedule and that means there is no point in lying in bed awake for 2 hours. Your mind wants to see production.
M:(3-3) You say "Set a bedtime" and "Don’t he awake in bed".
W: Absolutely right!
M:(3-4) And also "Persevere".
This is the end of Part One of the interview. Questions 1 to 5 are based on what you have just heard.
1. Which of the following statements can NOT explain why most people have trouble sleeping?
2. What proportion of the general population suffers from chronic insomnia according to the National Institute of Health?
3. Which of the following suggestions is NOT given for those with primary insomnia?
4. What time is advised to sleep at for those who can’t get to sleep?
5. What should a person do if he isn’t tired until 3 a. m. ?