【单选题】{{B}}第三篇{{/B}}
Coffee lovers beware. Having a quick "pick-me-up" cup of coffee late in the day will play havoc with you sleep.As well as being a stimulant, caffeine interrupts the flow of melatonin, the brain hormone that send people into a sleep.
Melatonin levels normally start to rise about two hours before bedtime. Levels then peak between 2A、m. and 4A、m., before falling again. "It’s the neurohormone that controls our sleep and tells our body when to sleep and when to wake," says Manrice Ohayon of the Stanford SleepEpidemiklogy ResearchCenter at Stanford University inCaliforniA、But researchers in Israel have found that caffeinated coffee halves the body’s levels of this sleep hormone.
Lotan Shilo and a team at the Sapir MedicalCenter in TelAviv University found that six volunteers slept less well after a cup of caffeinated coffee than after drinking the same amount of decaf. On average, subjects slept 336 minutes per night after drinking caffeinated coffee, compared with 415 minutes after decaf. They also took half an hour to drop off--twice as long as usual-- and jigged around in twice as much.
In the second phase of the experiment, the researchers woke the volunteers every three hours and asked them to give a urine sample. Shilo measured concentrations of a breakers were half those in decaf drinkers. The results suggest that melatonin concentrations in caffeine drinkers were half those in decaf drinkers. In a paper accepted for publication in Sleep Medicine, the researchers suggest that caffeine blocks production of the enzyme the drives melatonin production.
Because it can take many hours to eliminate caffeine from the body, Ohayon recommends that coffee lovers switch to decal after lunch.
B．Different findings of Lotan Shilo and a team about caffeine.
C．The fact that the subjects slept 415 minutes per night after drinking decaf.
D．The evidence that the subjects took half an hour to fall asleep.
网考网参考答案：A
网考网解析：
[解析] 该题考察判断指定段落的大意，因此关注段落中的观点句。段落第一句中就出现了明显表示其所在的句子是观点的结构：“某某专家find(发现)……”Lotan Shilo and a team at the Sapir Medical Center in Tel Aviv University found that six volunteers slent less well after a cup of caffeinated coffee than after drinking the saine amount of decaf．因此可以直接借助该句句意判断答案。该句说“Lotan Shilo和一个研究小组发现六个志愿者在喝了一杯含咖啡因的咖啡后其睡眠状况不如喝了等量的脱咖啡因的咖啡后睡眠好。”因此判断A“含咖啡因的咖啡和不含咖啡因的咖啡对睡眠带来的不同影响”是答案。 document.getElementById("warp").style.display="none"; document.getElementById("content").style.display="block"; 查看试题解析出处>>
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