单项选择题

Chronic insomnia is a major public health problem. And too many people are using (1) therapies, even while there are a few treatments that do work. Millions of Americans (2) awake at night counting sheep or have a stiff drink or (3) an pill, hoping it will make them sleepy. (4) experts agree all that self-medicating is a bad idea, and the causes of chronic insomnia remain (5) .a

Chronic insomnia is a major public health problem. And too many people are using (1) therapies, even while there are a few treatments that do work. Millions of Americans (2) awake at night counting sheep or have a stiff drink or (3) an pill, hoping it will make them sleepy. (4) experts agree all that self-medicating is a bad idea, and the causes of chronic insomnia remain (5) .
Almost a third of adults have trouble sleeping, and about 10 percent have (6) of daytime impairment that signal true insomnia. But (7) the complaints, scientists know surprisingly little about what causes chronic insomnia, its health consequences and how best to treat it, a panel of specialists (8) together by the National Institutes of Health concluded Wednesday. The panel called (9) a broad range of research into insomnia, (10) that if scientists understood its (11) causes, they could develop better treatments.
Most, but not all, insomnia is thought to (12) other health problems, from arthritis and depression to cardiovascular disease. The question often is whether the insomnia came first or was a result of the other diseases and how trouble sleeping in (13) complicates those other problems. Other diseases (14) , the risk of insomnia seems to increase with age and to be more (15) among women, especially after their 50s. Smoking, caffeine and numerous (16) drugs also affect sleep.
The NIH is spending about $200 million this year on sleep-related research, some (17) to specific disorders and others (18) the underlying scientific laws that control the nervous system of sleep. The agency was (19) the pane’s review before deciding what additional work should be (20) at insomnia.

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