Question

Doctors sometimes use light therapy to treat a form of depression in people who get too little morning sun. But too much light at other times may actually cause such mood disorder. Long-lasting exposure to light at night brings depression, a new study finds, at least in animals.

The new data confirm observations from studies of people who work night shifts, says Richard Stevens of the University of Connecticut Health Center. Mood disorders join a growing list of problems, including cancer, obesity and diabetes that can occur when light throws life out of balance by disturbing the biological clock and its timing of daily rhythms.

In the new study, Tracy Bedrosian and Randy Nelson of Ohio State University exposed mice to normal light and dark cycles for four weeks. For the next four weeks, half of the mice remained on this schedule, and the rest received continuous dim light throughout their night. Compared with mice exposed to normal night-time darkness, those getting dim light at night lost their strong preference for sweet drinks. “A sign that they no longer get pleasure out of activities they once enjoyed,” Bedrosian says.

In a second test, mice were clocked on how long they actively tried to escape a pool of water. Those exposed to night lights stopped struggling and just floated in the water, a sign of “behavioral despair”, 10 times as long as the mice that had experienced normal night-time darkness. All symptoms of depression disappeared within two weeks of the mice returning to a normal light-dark cycle, the researchers report. The scientists could also quash the behavioral symptoms by injecting the brains of animals with a drug that prohibits the activity of certain molecules linked with human depression. This finding further suggests that light at night may cause something related to depression.

Human studies linking night-time light and mood disorders are important but can not easily detect molecular underpinnings(分子基础) as animal studies can, says George Brainard of Thomas Jefferson University. The new work, he says, suggests that the change of the biological clock by light at night can be “an extremely powerful force in regulating biology and behavior”.

1.After being exposed to continuous night-time light, the mice __________.

A. changed their preferences

B. escaped from the water more eagerly

C. remained active as before

D. showed less interest in their favorites

2.What does the underlined word “quash” in paragraph 4 probably mean?

A. study            B. predict

C. ease              D. cause

3.We can learn from the last paragraph that _______________.

A. light at night may have practical value

B. the biological clock is beneficial to humans

C. human mood disorders cannot be healed easily

D. human studies are more important than animal studies

4.What is the main idea of the passage?

A. Night-time light may cause depression.

B. A drug has been found to cure mood disorders.

C. The study on animals can be applied to humans.

D. Human biological clock can be controlled by light.

Answer

1.D

2.C

3.A

4.A

【解析】

试题分析：一项研究表明，至少在动物身上，长时间暴露于夜晚的光线会带来沮丧，并用小白鼠进行试验论证。

1. with mice exposed to normal night-time darkness, those getting dim light at night lost their strong preference for sweet drinks.句意：与暴露在正常的夜晚黑暗中的小白鼠相比，那些在夜晚得到昏暗灯光的小白鼠失去了对天的饮料的强烈偏好。得知此类小白鼠的偏好会受光照改变。故选D

2. scientists could also quash the behavioral symptoms by injecting the brains of animals with a drug that prohibits the activity of certain molecules linked with human depression句意：科学家们也能通过像动物大脑注射一种药物来消除这种行为性症状，这种药物会阻止某些和人类沮丧相联系的分子运动。以及上一句中All symptoms of depression disappeared…所有的沮丧症全部消失了……得知这里quash在与ease意思相近：使无效，平息。故选C

3. 对人类的关于夜晚光线和情绪紊乱的研究很重要，但是却不能像对动物的研究那么容易的探测到分子基础，Tomas Jefferson大学的George Brainard说道。他说，新的工作暗示着由夜晚光线导致的生物钟的改变可能是“在调控生物学和行为学方面非常有力的力量”。得知其强调的是light at night may have practical value夜晚的光线有特殊的作用，故选A

4. exposure to light at night brings depression, a new study finds, at least in animals(一项研究表明，至少在动物身上，)，以及第四段最后一句This finding further suggests that light at night may cause something related to depression（这种发现进一步表明夜晚的光线会导致和沮丧相关的事情）。故选A

考点：考查科学实验类说明文阅读。