9．Why can some people sleep through noises like a honking car or flushing toilet，while others are awakened by the lightest sound？
To find the answer，sleep researchers at Massachusetts General Hospital conducted an unusual study of 12self-described deep sleepers．After tests confirmed that the healthy volunteers were solid sleepers，they took part in a three-night study in the university's sleep laboratory．The participants spent the night in a big and comfortable room．But the room also included four speakers positioned near the top of the bed．
During the night，the deep sleepers were subjected to 14different recorded sounds，like street traffic，toilets flushing，an ice machine dispensing and an airplane flying overhead．Next door，the researchers monitored their sleep patterns and brain waves．
As expected，all of the participants slept relatively well，but there were differences in how they responded to the noisy interruptions．Some of the sleepers didn't wake up even when a sound was blasted at 70decibels （分贝）； others were awakened by sounds at 40or 50decibels．
The researchers discovered that the difference in a sleeper's reaction to noise could be predicted by the level of brain activity called"sleep spindles''．A sleep spindle is a burst of high-frequency brain activity coming from deep inside the brain during sleep．The source of the spindles is the thalamus，a part of the brain that sends sensory information to the rest of the cortex （皮层）．
Before the study，the Massachusetts researchers theorized （推理） that the spindles are the brain's way of preventing sensory information from passing through the thalamus and waking the rest of the brain during sleep．They found that the sleepers who experienced the most sleep spindles during the night were also the soundest sleepers and were least likely to be awakened by noise．
Scientists already know that most people become lighter sleepers with age，most likely because older people experience less"slow wave sleep''，which is the deepest stage of sleep．People also produce fewer sleep spindles as they age．But even when controlling for the stage of sleep a person was in，the number of sleep spindles still predicted their risk for awakening because of noise．
More research is needed，but the findings suggest that a better understanding of sleep spindles could lead to new behavioral or drug therapies for people with sleep disorders．For instance，future studies may try to determine whether diet，exercise or other behaviors may influence the number of sleep spindles a person produces during the night．
63．Some participants can sleep well through loud noises mainly becauseB．
A．their brains don't respond to outside noises
B．their brains react differently to noises
C．they adapt to the environment quickly
D．they don't pay attention to the monitors
64．Scientists believe that the key to affecting deep sleep isA．
A．sleep spindles B．stages of sleep C．sleep disorders D．sensory information
65．It can be learned from the passage thatB．
A．the older a deep sleeper becomes，the lighter his sleep must be
B．the more"slow wave sleep"one experiences，the deeper sleep one has
C．the more frequently a sleeper's brain works，the less information it sends
D．the deeper sleep people have，the more likely they will be awakened by noise
66．From the passage we can predictA．
A．more factors in influencing sleep spindles may be discovered
B．more solid sleepers will take part in relative experiments
C．sleep spindles will be applied to changing one's behaviors
D．deep sleepers will probably enjoy a more healthy life．
分析 本文讲述了研究人员对人们在极大的噪音下的睡眠问题，结果显示大脑对噪音的反应程度的不同会极大影响到睡眠情况．
解答 63．B 细节理解题．根据文章第四段的内容As expected，all of the participants slept relatively well，but there were differences in how they responded to the noisy interruptions 参加者们都睡的着，但他们的区别在于对噪音的反应是不一样的，故答案选B．
64．A 细节理解题．根据文章第五段的内容They found that the sleepers who experienced the most sleep spindles during the night were also the soundest sleepers and were least likely to be awakened by noise．可知，睡眠纺锤复合波会是深度睡眠的关键，故答案为A．
65．B 推理判断题．根据Scientists already know that most people become lighter sleepers with age，most likely because older people experience less"slow wave sleep''，which is the deepest stage of sleep 科学家 研究发现人们会随着年龄的增长而睡眠变浅，那是因为老人会经历更少的"slow wave sleep''，而这种状态正是睡眠的最深状态，由此可判断B为正确选项．
66．A 推理判断题． 根据文章最后一段总结可知，研究人员会对饮食、锻炼以及其他进行研究，以得知其是否会对sleep spindles 有影响，再结合选项，故选A．
点评 本文是健康环保类阅读理解．做这类题材阅读理解时要求考生对文章通读一遍，做题时结合原文和题目有针对性的找出相关语句进行仔细分析，结合选项选出正确答案．推理判断题也是要在抓住关键句子的基础上合理的分析才能得出正确答案，切忌胡乱猜测，一定要做到有理有据．
