Areyousickofgoingtobedlateandwakinguptired?Thengrabyour...

问题详情：

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.

38. The underlined word “fatigue” in Paragraph 4 probably means   _

A. excitement

B. tiredness

C. relief

D. disappointment

39. What did Wright's team discover from their experiment?

A. Those staying outdoors reset the clock inside their bodies over a short period.

B. The body clocks of the two groups didn’t show much difference.

C. The body clocks of those who stayed at home remained the same.

D. Changes to the body clock don't necessarily affect melatonin levels in our bodies.

40. According to the passage, to change our sleeping habit, we’ d better_      .

A. stay home to reset our body clock and get more sleep

B. stay up late long past sunset and sleep long after sunrise

C. get exposed to more natural light but less artificial light

D. try to reduce melatonin levels as much as possible at night

41. What is the author’s main purpose of writing the passage?

A. To inform us of a possible way to adjust the body clock.

B. To explain how a lack of sleep is bad for our health.

C. To analyze how the body clock influences our sleeping habits.

D. To explore how the body clock is connected with melatonin levels.

【回答】

BACA

知识点：科普环保类阅读

题型：阅读理解