2．Sleep is just as important as diet and exercise，and not getting enough sleep can lead to obesity，heart trouble and other health problems．Now scientists are adding more wake-up call to that list：lack of sleep damages the brain．
People who regularly have trouble falling asleep and staying asleep （one study drew the line at 6.8hours ） show changes in brain-----actual shrinking（缩小），in some cases---in area important for memory and problem solving．
"We've always believed that we can take the weekend to catch up and be fine，"says Sigrid Veasey，a researcher in University of Pennsylvania，but that may not be the case．When she stopped mice from sleeping for 3days，they lost 25% to 30% of the neurons （神经元） important for focused attention----and these remaining were damaged．What's more，these brain cells never grew again．
Clearly，something important is happening while we sleep，but exactly what sleep does for the brain has been a mystery．That's why scientists got excited when researchers at the university of Rochester Medical Center recently offered a new theory．While observing the brains of sleeping mice，they discovered a kind of brain-cleaning system that clears away neural waste，the buildup of which is connected with Alzheimer's．
In another study，young healthy people whose sleep was limited to 7hours per night for one week showed damaged brain function．Scarier is that with long-lasting short sleep，you may feel fully rested．When study subjects were limited to 4hours of sleep for 5days，they reported feeling very tired following the first night but they didn't get any sleepier after that．
What's more，a 15，000-person study found that getting an average of less than 5hours of sleep per night for several years resulted in a decrease in memory performance equal to the brain aging 2years．
Have we persuaded you to turn in early tonight？Excellent．
32．The text is mainly aboutA．
A．how lack of sleep damages our brain．
B．why we feel rested without enough sleep．
C．how much sleep we should get every day．
D．Why we have trouble falling asleep sometimes．
33．Sigrid Veasey's research shows thatB
A．lack of sleep doesn't affect our attention．
B．damaged brain cells can not recover．
C．sleeping on weekends can make up for lost sleep．
D．most neurons will die if we sleep poorly for 3days．
34．According to paragraph 5，after several days of short sleep people may feelC．
A．tired
B．sleepy
C．energetic
D．angry
35．According to the 15，000-person study，lack of sleep may causeD．
A．heart trouble
B．obesity
C．death
D．memory loss．
分析 研究表明缺少睡眠会导致肥胖，心脏病和其它的疾病．现在科学家又发现缺少睡眠会损害大脑．
解答 32．A考查主旨大意题．根据第一段内容Now scientists are adding more wake-up call to that list：lack of sleep damages the brain．可知本文说的是缺少睡眠会损害大脑．故选A．
33．B 考查细节理解题．根据第二段内容When she stopped mice from sleeping for 3 days，they lost 25% to 30% of the neurons （神经元） important for focused attention----and these remaining were damaged．What's more，these brain cells never grew again．可知他让老鼠3天不睡觉，老鼠的神经元就会减少25%到30%，而且脑细胞再也不会生长了．故选B．
34．C考查推理判断题．根据第五段内容Scarier is that with long-lasting short sleep，you may feel fully rested．"可知经历长时间的少睡眠后，人仍然会感到fully rested，即energetic（精力充沛的）．故选C．
35．D考查细节理解题．根据最后一段内容What's more，a 15，000-person study found that getting an average of less than 5 hours of sleep per night for several years resulted in a decrease in memory performance equal to the brain aging 2 years．可知每晚平均睡眠少于5小时，持续几年会导致记忆力降低，相当于大脑老化了2年．故选D．
点评 本文是科教类阅读理解．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
