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  3. I’ve often wondered how exactly sleep, or lack of it, can have such an awful effect on our bodies and, guess what, how much we s

I’ve often wondered how exactly sleep, or lack of it, can have such an awful effect on our bodies and, guess what, how much we s

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问题    I’ve often wondered how exactly sleep, or lack of it, can have such an awful effect on our bodies and, guess what, how much we sleep switches good genes on and bad genes off.
   In the first half of 2013, the Sleep Research Centre at the University of Surrey found a direct link between hours spent sleeping and genes. Every cell in our bodies carries genetic instructions in our DNA that act as a kind of operating handbook. However, each cell only "reads" the part of this handbook it needs at any given moment.
   Can sleep affect how a gene reads instructions? It’s a question asked by Professor Derk-Jan Dijk at the University of Surrey. He set up an experiment and asked his volunteers to spend a week sleeping around seven and a half hours to eight hours a night and the next sleeping six and a half to seven hours.
   Blood samples were taken each week to compare which genes in blood cells were being used during the long and short nights. The results were rather surprising. Several hundred genes changed in the amount they were being used, including some that are linked to heart disease, cancer, and Type 2 diabetes. Genes to do with cell repair and replacement were used much less.
   Sleep restriction (six and a half to seven hours a night) changed 380 genes. Of these, 220 genes were down regulated (their power was reduced), while 160 were up regulated (their power was increased). Those affected included body-clock genes which are linked to diabetes. One of the most downgraded genes is that which has a role in controlling insulin and is linked to diabetes and insomnia. The most upgraded gene is linked to heart disease.
   So changing sleep by tiny amounts can upgrade or downgrade genes that can influence our health and the diseases we suffer from when we sleep too little.
   The important message is that getting close to eight hours of sleep a night can make a dramatic difference to our health in just a few days through the way it looks after our genes.
What can we learn about Professor Derk-Jan Dijk’ s experiment?
选项 A、The experiment was carried out to find the answer to how genes affect sleep.
B、The experiment took a period of more than two weeks to reach a conclusion.
C、His volunteers were divided into two groups with two different sleeping patterns.
D、Blood samples of the volunteers were checked afterwards to decide how many genes changed in sleeping.
答案B
解析 推断题。定位于第三段和第四段。根据第三段的第一句话“Can sleep affect how a gene reads instructions?”可知Derk-Jan Dijk教授的实验是为了发现睡眠对人体基因变化的影响，而不是基因影响睡眠，故A项不正确。根据第三段的最后一句话“He set up an experiment and asked his volunteers to spend a week sleeping around seven and a half hours to eight hours a night and the next sleeping six and a half to seven hours．”可知，他并没有将志愿者进行分组，而是要求他们第一周每晚睡七个半到八个小时，第二周将睡眠时间调整为六个半到七个小时，故C项不正确。再结合第四段的前两句话，他将志愿者这两周的血液样本进行比对，观察基因运作情况的不同，实验结果令人大吃一惊。由此可推断出，这个实验进行了两周多才得出结论，故B项正确，D项不正确，采集血液样品是为了比较在不同睡眠时长下所用到的基因的不同，而不是多少基因被改变。
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