题目

阅读理解 For a good night's sleep, here is some expert advice: Turn off, turn in and drop off. Anyone who does the opposite—turning on an iPad or other similar electronic readers in bed — may have a harder time both dropping off to sleep and shaking that weak feeling the next morning, a new study found. Sleep experts at Brigham and Women's Hospital in Boston, found that the light from a tablet computer upsets the body's internal (体内的) clock while reading a printed book does not have the same effect. An internal clock helps regulate when we sleep. Exposure to the light of day and darkness of night keeps its timing set to a roughly 24-hour cycle. Starting about two hours before bedtime, our brains start to produce a hormone called melatonin (褪黑激素), which signals our internal clock that darkness has fallen and prepares the body for sleep. Scientists have known for long that light at night can mess with that internal clock. And it does so by suppressing（抑制）melatonin, thus preventing the body from getting the message that bedtime is near. For their new study, the researchers recruited(招募) six men and six women, all in their mid-20s. Over two weeks, each spent four hours reading each evening before a 10: 00 pm bedtime. The volunteers read on an iPad for five nights in a row. On another five evenings they read a printed book. Participants took nearly 10 minutes longer to fall asleep, on average, after reading on the iPads. They also spent less time in rapid-eye movement sleep which appears important for learning and storing memories. There was no difference in hours spent sleeping after reading from either the iPad or a printed book. But how volunteers felt the next day did differ. "Our most surprising finding is that participants using the e-reader would be more tired and take longer to become alert (警觉的) the next morning, says sleep researcher Ann-Marie Chang. （1） What is paragraph 3 intended to stress? A . The significance of the internal clock for sleep. B . The relationship between internal clock and time. C . The necessity of going to bed earlier regularly. D . The importance of melatonin for new lifestyles. （2） What does the underlined word "it" in paragraph 4 refer to? A . The sleep disorder. B . The delayed message. C . Light at night. D . An internal clock. （3） How did the researchers try to show the results of the study? A . By making comparisons. B . By giving some examples. C . By explaining the principles. D . By telling causes and effects. （4） What can be a suitable title for the text? A . An Internal Clock Has Control Over Sleep B . Electronic Readers Should Be Formally Avoided C . Reading Before the Night Sleep Leads to Health Problems D . Screen Time Before Bedtime Can Disturb the Body's Clock 答案： A C A D

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