Are you sick of going to bed late and waking up tired? Then grab your hiking boots and a tent. A new study suggests that camping in the great outdoors for a couple of days can reset your body clock and help you get more sleep.
The body clock is an internal system that tells our bodies when it's time to go to sleep and when it's time to wake up. Scientists track this clock by measuring the amount of melatonin (褪黑激素) circulating in a person's blood at any given time.
In a healthy sleeper, melatonin levels rise a few hours before bedtime, stay high through the night, and then settle back down when it's time to wake up.
In our modern society, however, most of us stay up many hours past sunset and would probably sleep in many hours after sunrise if we could. And the trouble is, your melatonin levels may still be high when your alarm clock goes off in the morning, which leads to fatigue. It may also have other health consequences as well, such as diabetes(糖尿病), overweight and heart disease.
Professor Kenneth Wright of the University of Colorado in the US wanted to see if our body clocks can be reset by a short stay in nature. His team recruited(招募)fourteen physically active volunteers in their 20s and 30s. Nine went on a weekend camping trip, while the other five stayed home. At the end of the weekend, the researchers reported that in just two days, the campers' body clocks had shifted so that their melatonin levels began to rise more than an hour earlier than they did before they left on the trip. By contrast, the body clocks of the group that stayed home shifted even later over the course of the weekend.
“This tells us we can reset our clocks fast，”Wright said.
Therefore, if you want to change your sleep patterns you could try to increase your exposure to natural light during the day and decrease the amount of artificial light you see at night. And if that doesn't work, there's always camping.
本文为说明文。生物钟对人体的影响很大。生物钟如遭到破坏，可能会影响人的健康，如患糖尿病，身体肥胖，心脏病，尤其是影响我们的睡眠。一项新研究称几天的户外露营便可以重启你的生物钟，帮助你改善睡眠。
1．What is the author's main purpose of writing the passage?
A．To explain how a lack of sleep is bad for our health.
B．To inform us of a possible way to adjust the body clock.
C．To analyze how the body clock influences our sleeping habits.
D．To explore how the body clock is connected with melatonin levels.
答案：B
解析：推理判断题。第一段中的A new study suggests that camping in the great outdoors for a couple of days can reset your body clock and help you get more sleep. 一项新的研究表明，在户外露营几天可以重置你的生物钟，帮助你获得更多的睡眠。及最后一段Therefore，if you want to change your sleep patterns you could try to increase your exposure to natural light during the day and decrease the amount of artificial light you see at night. And if that doesn't work，there's always camping. 因此，如果你想改变你的睡眠模式，你可以试着增加白天暴露在自然光下的量，减少晚上看到的灯光的量。如果这不起作用，还可以露营。由此可知这是告诉我们一种调节人的生物钟的方法。B正确。
2．The underlined word “fatigue” in Paragraph 4 probably means“________”．
A．tiredness B．excitement
C．refreshment D．pressure
答案：A
解析：猜测词义题。结合第四段中的your melatonin levels may still be high when your alarm clock goes off in the morning 早上闹钟响起的时候，体内的褪黑激素还依然保持较高水平，因此就会使人感到劳累。可知“fatigue”指的是疲劳的。A正确。
3．What did Wright's team discover from their experiment?
A．The body clocks of the two groups didn't show much difference.
B．The body clocks of those who stayed at home remained the same.
C．Those staying outdoors reset the clock inside their bodies over a short period.
D．Changes to the body clock don't necessarily affect melatonin levels in our bodies.
答案：C
解析：细节理解题。根据五段中的At the end of the weekend，the researchers reported that in just two days，the campers' body clocks had shifted so that their melatonin levels began to rise more than an hour earlier than they did before they left on the trip. By contrast，the body clocks of the group that stayed home shifted even later over the course of the weekend. 周末结束时，研究人员报告说，仅仅两天内，露营者的生物钟就改变了，褪黑激素水平比他们出门旅行前提前了一个多小时开始上升。由此可判断出Wright的团队经过对比两组人群的睡眠表现发现，我们可以在短时间内调整生物钟。故选C项。
4．According to the passage, to change our sleeping habit, we'd better ________.
A．set an alarm clock to wake us up on time in the morning
B．try to reduce melatonin levels as much as possible at night
C．spend several weeks staying in the open air every now and then
D．get exposed to more natural light in the day but less artificial light at night
答案：D
解析：细节理解题。根据最后一段if you want to change your sleep patterns you could try to increase your exposure to natural light during the day and decrease the amount of artificial light you see at night.得知，白天暴露在自然光下，晚上减少可见的人造光线，就可以改善我们的睡眠习惯。D项符合题意。
