Werewolves (狼人) aren’t the only creatures affected by the moon’s cycles（周期）. A full moon also affects people’s sleep more or less, reports a Swiss team of scientists. Even people who sleep in a lab without windows could reduce their sleeping time a little once a month.
To test the moon’s influence, 33 adults of both sexes and ages of many kinds spent several nights in a sleep lab. As they slept, researchers recorded their brain activity, eye movements and hormone levels (荷尔蒙水平). On nights closer to a full moon, the sleepers took an average of five minutes longer to fall asleep, and slept for 20 minutes less. In addition, brain activity fell by 30 percent during the sleep. And hormone levels that help control sleep cycles went down. On these nights, the sleepers complained they couldn’t sleep well even though they didn’t know the moon’s cycle. On the bright side, no sleeper turned into a werewolf.
The Swiss team doesn’t know how the moon affects sleep. The gravity (重力) of the moon causes ocean tides（潮汐）to rise and fall. But that force is too weak to affect sleep, Gajochen says. He believed some body’s biological clock may be affected by the moon cycles. There may be another reason, says David Dinges. This sleep researcher at the University Of Pennsylvania in Philadelphia says that the body clock is very sensitive（敏感的）to light at night. Those sleepers could have been affected by having too much moonlight before arriving at the lab.
24．The writer mentioned “werewolves” in the first paragraph to ________.
A. show there are the moon’s cycles
B. attract people’s attention to the report
C. introduce a creature to readers
D. ask people not to sleep alone in the lab
25．What happened to the sleepers during the experiment on a full moon?
A. They slept for about five minutes longer.
B. They could only sleep for 20 minutes.
C. Their brains were not as active as they were
D. They complained they were too tired to sleep.
26．The last paragraph is developed mainly by ________.
A. analyzing (分析) reasons B. explaining differences
C. making comparisons D. following the time order
27．The passage is mainly about ________.
A. the sleeping problems caused by the moon’s cycles
B. the influence of the moon on human sleeping habits
C. the moon’s influence on sleeping and its possible reasons
D. the ways to get a better sleep on a full moon night