For many of us, a little time with our smartphones or iPads before sleep is the highlight of the night. But would you still think it is relaxing if you knew that it damages or destroys your sleep? Scientists say that's exactly what it does.
In ancient times, when there were no lamps, telephones or smartphones, the sun was the main source of light. When the sun went down, our brains took that as a signal to start producing melatonin(褪黑素), a chemical that helps us sleep.
However, a healthy amount of melatonin can only be produced in complete darkness.Any light in your bedroom—even the one on the alarm clock or the charging indicator on your cellphone—could disturb the process, not to mention something as bright as smartphone and iPad screens. We tend to hold these much closer than a television or laptop, which allows them to shoot far more light straight into our eyes.
“This is particularly worrisome in populations such as young adults and adolescents, who already tend to be night_owls，” said researcher Brittany Wood at Rensselaer Polytechnic Institute.“Lack of sleep among teens is leading to depression, selfharm, low concentration and poor performance at school，” she added.
While all lights are the enemy of sleep, not all colors of light have the same effect. Our eyes are particularly sensitive to blue light, which is common during the day. Most of the light coming from electronic screens is blue light and it fools our brain into thinking it's still daytime. By contrast, orange or red light has less influence on melatonin production, because our brains recognize it as a signal that the day is ending, according to The Telegraph.
Asking yourself to keep your hands off your smartphone before bedtime might seem unreasonable, but you should at least remember to dim the screen or hold it farther away from your eyes. You could also wear a pair of orange sunglasses that take away the harmful blue light.
小题1:According to the passage, we can know ________.
A．it's a good habit to play with smartphones or iPads late into night
B．scientists suggest we should avoid using smartphones or iPads
C．darkness makes a great impact on the amount of melatonin
D．the sun was the only source of light in ancient times小题2:Which of the following is TRUE according to the passage?
A．The darker it is, the more melatonin will be produced.
B．The lighter it is, the more melatonin will be produced.
C．The more melatonin you have, the worse you'll sleep.
D．The more electrical equipment you have, the more melatonin will be produced.小题3:The underlined part in Paragraph 4 refers to those ________.
A．who are young adults or adolescents
B．who don't perform well in school
C．who are addicted to a television or laptop
D．who are short of sleep at night and perform poorly in daily life小题4:In the writer's opinion, which is a correct suggestion?
A．You should go to bed when the sun goes down.
B．You should use an orange or red light electronic screen.
C．You should wear a pair of blue sunglasses when sleeping.
D．You should avoid blue light as possible as you can before bedtime.
小题1:C
小题2:A
小题3:D
小题4:D
本文是一篇科技说明文。研究发现，睡前玩手机可能会影响睡眠状况。
小题1:答案：C 推理判断题。根据第二段最后一句及第三段第一句可知，C项正确；根据第一段内容可知，A项错误；根据文章内容可知，科学家们只是建议睡前不要玩手机，故B项错误；根据第二段中的“In ancient times，when there were no lamps，telephones or smartphones，the sun was the main source of light.”可知D项为错误结论。
小题2:答案：A 推理判断题。根据第二段中的“our brains...a chemical that helps us sleep”及第三段首句“However，a healthy amount of melatonin can only be produced in complete darkness.”可知A项正确并排除B、C两项。根据第三段中的“even the one on the alarm clock or the charging indicator on your cellphone—could disturb the process，not to mention something as bright as smartphone and iPad screens.”可排除D项。
小题3:答案：D 推理判断题。根据第四段内容尤其是最后一句可知，night owls指的就是晚上熬到很晚，缺乏睡眠，然后白天不能集中精神，表现不好的那些人。故D项正确。
小题4:答案：D 细节理解题。根据倒数第二段内容可知，并不是所有颜色的光都会产生同样的作用。我们的眼睛对蓝色的光尤为敏感，它会传递给我们的大脑错误的信息，让大脑以为还在白天，因此会影响我们的睡眠，所以在睡觉前应避免接触蓝光。D项正确。