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  3. The curse of jet lag has struck most international travelers at one time or another -- and anyone lucky enough to have avoided i

The curse of jet lag has struck most international travelers at one time or another -- and anyone lucky enough to have avoided i

admin2011-04-04  110
问题     The curse of jet lag has struck most international travelers at one time or another -- and anyone lucky enough to have avoided it will surely have suffered the equally unpleasant sleep-deprivation involved in an early-morning start. Nor, as shift workers know too, is it possible to escape by going to bed earlier the previous evening, and thus putting sleep in the bank. Sleepiness is controlled by the body’s internal biological clock, so an earlier bedtime just means several wakeful hours staring in frustration at a darkened ceiling.
    For years, some travelers and shift workers have sworn by melatonin (褪黑素). This is a hormone that regulates the biological clock. It is made in the brain by a structure called the pineal gland (松果体), as darkness sets in after sunset. Light is the one that keeps the biological clock in the same pace with solar time. The clock then tells the brain when to go to sleep. The theory of those who use melatonin is that an external dose of it can reset the clock, and thus cause the "go to sleep" signal to be sent at a more convenient moment~ Melatonin can also increase sleepiness during the day, when the pineal gland is not producing it.
    This has resulted in a growing, and often unregulated, market in melatonin-supplement tablets. The pharmaceutical industry’s response to this seems to be: "If you can’t beat them, join them." A paper in this week’s Lancet, by Shantha Rajaratnam of the Harvard Medical School and his colleagues, reports two trials, funded by drug companies, of tasimelteon, a substance that binds to the same receptors in the brain as melatonin does, and which it is expected will have a similar effect.
    In the course of these trials, more than 400 people had their bedtimes brought forward by five hours in controlled conditions. Half an hour before lights out, a quarter of them were given common drug, while the remaining three-quarters were given varying doses of tasimelteon. Dr. Rajaratnam and his colleagues report that the new drug let people fall asleep faster at the unnaturally early time, and also allowed them to sleep longer than those given the common one.
Tasimelteon and melatonin have the similar effect because they connect with ______.
选项
答案the same receptors in the brain
解析 题干问的是新药tasimelteon的作用机理，故将本题出处定位到第三段。根据similar effect定位到最后一句。原文提到，tasimelteon这种物质与melatonin一样都与the same receptors in the brain有关联。原文中用的是the same…as…结构，题干把as前后的比较对象用一个they都包括了，connect with对应原文中的binds to。直接从原文摄取答案即可。
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