Question

    In today's world, sleep experts often say that for a better night's rest, Americans should turn off their smart phones or iPads before sleeping. Such electronic products make the brain more active, and then influence their sleep. But according to a latest survey, more than 90% of Americans often use a computer or some other kinds of electronic products in the hour before bed.

Researchers find that man­made light from some electronic products at night may reduce the brain chemicals that help to sleep. In the study, the researchers let volunteers read, play games and watch movies on a screen for different time while measuring how much light their eyes received. They found that two hours of sitting before a bright screen at night reduced the sleep chemical levels by about 22%.

Then the researchers studied the college students who often used computers at night. They got the similar results. And researchers say that may not only cause sleeplessness, but also raise the risk of obesity(肥胖症), diabetes(糖尿病) and other diseases.

To be on the safe side, the researchers suggest that we should use computer less than before, or turn down our screens as much as possible before sleeping.

说明：21、22题完成句子；23题简略回答问题；24题用英语简要概括文章的主旨大意；25题将文中画线句子译成汉语。

1.Electronic products can ______________ and influence people's sleep.

2.Man­made light______________ may reduce the brain chemicals which help   to  sleep at night.

3.What did researchers let volunteers do in the study?

___________________________________

4.The passage mainly tells us _____________________________________.

5.________________________________________________________________________

Answer

1.make the brain more active

2.from some electronic products

3.Let them read, play games and watch movies on a screen for different time.

4.electronic products influence our sleep

5.研究者建议我们应比之前更少地使用电脑。

【解析】

本文是一篇说明文。主要介绍了电子产品对睡眠的影响。专家们进行了一系列研究和实验，并说明其中危害。研究者建议我们睡觉前少玩电脑或者尽可能地减弱屏幕的亮度。