Many of us have had this experience: We lie down in a bed other than our own, perhaps at a friend’s house or in a hotel room, and find it difficult or impossible to fall asleep. Is it because the bed is uncomfortable? Maybe, but perhaps there can be other reasons.

According to a new study published in Current Biology, an important reason is what the scientists call “first night effect”. They believe that one side of the brain acts as a “night watch” to warn us about potential（潛在的） dangers. It forces us to stay awake on the first night in a new environment.

For the study, 35 young volunteers were asked to sleep in a sleep lab for several days. Meanwhile, researchers watched their brain activities.

According to the researchers, on their first night, the left brains were more active than the right brains and people had a hard time sleeping. However, left-brain activity decreased as days went by, falling even to the point of complete quietness. So, the volunteers got an increasingly better sleep experience.

The findings suggest that the different rhythms（節(jié)奏） of the sides of the brain influence our sleep. When the two sides work differently, the balance between them is broken. And the brain can’t relax, just as it is in the daytime.

US professor Jerome Siegel told Smithsonian magazine, “If something unusual happens—if a door opens or you hear a key in a lock—you can be alert（警惕的）, even though the sound is quite low.” It works to protect us in a dangerous environment.

More surprisingly, this situation is similar to the way some animals sleep. Whales, dolphins, and many birds can sleep with half of their brain while the other half stays awake, with its one eye staying open.

If you have ever had what you think is “first night effect”, researchers suggest that you bring your own pillow（枕頭） or sleep in a room similar to your bedroom next time you sleep away from home.

【1】The cause of “first night effect” is that_____________ .

A.the left brains begin to relaxB.the right brains have a hard time

C.one side of the brains is more activeD.two sides of the brains need more rest

【2】Researchers find that “first night effect”_____________ .

A.protects people from dangerB.helps animals sleep better

C.affects less in the daytimeD.causes something unusual

【3】To solve the problem of “first night effect”, we’re advised to_____________ .

A.study the pictures of more animalsB.learn from the way animals sleep

C.lie in a more comfortable bedD.get used to new environments

【4】The passage might be taken from a part of a_____________ .

A.travel posterB.news report

C.science magazineD.school notice

—She is of medium build with long straight hair.

A. look like B. looks like C. like D. likes

A. I agree. B. I think so.

C. I don’t agree. D. I don’t know.

A. result B. results C. reason D. reasons

A. sound B. feel C. taste D. Look

- Really? Could you please show me ____ it?

A. what to do B. how to do C. when to do D. why to do

A. will spend；will be B. spend；is

C. spend；will be D. will spend；is

A. bring out B. care for C. take up D. look for

–We must keep our hair _______, and we must wear the school uniform.

A. tall B. thin C. warm D. Short

–Yes. Geography is my favorite subject.

A. are B. do C. did D. Have