题目内容
Late-night Drinking
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 2 a.m. and 4 a.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 Sleep Epidemiklogy Research Center at Stanford University in California. 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 Medical Center in Tel Aviv 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.
The author mentions "pick-me-up" to indicate that______.
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Diet, Alcohol Linked to Nearly One Third of Cancers
Diet is second only to tobacco as a leading(1)of cancer and，along with alcohol，is responsible for nearly one third of cases of the disease(2)developed countries, a leading researcher said on Tuesday.
Dr. Tim Key, of the University of Oxford, told a cancer conference that scientists are still discovering how certain foods contribute to(3), but they know that diet, alcohol and obesity(4)a major role.
"Five percent of cancers could be avoided(5)nobody was obese," he said.
While tobacco is linked to about 30(6)of cancer cases, diet is involved in all estimated 25 percent and alcohol(7)about six percent.
Obesity raises the(8)of breast, womb, bowel and kidney cancer, while alcohol is known to cause cancers of the mouth, throat and liver. Its dangerous impact is(9)when combined with smoking.
Key told the meeting of the charity Cancer Research UK(10)other elements of diet linked to cancer are(11)unknown but scientists are hoping that the EPIC study, which is comparing the diets of 500, 000 people in 10 countries and their risk of cancer, will provide some(12)
Early results of the study have revealed that Norway, Sweden and Denmark have the(13) consumption of fruit and vegetables among European countries while Italy and Spain have the highest. Eating at(14)five portions of fruit and vegetables a day is recommended to reduce the risk of cancer.
Key, principal scientist on the EPIC study, said it is looking at dietary links to some of the most common cancers(15)colorectal, breast and prostate.
obesity n. 肥胖
bowel n.肠
dietary adj. 饮食的
prostate adj. 前列腺的
obese adj. 肥胖的
womb n.子宫
colorectal adj. 结肠直肠的
Less-educated people report fewer days of stress possibly because
The less advantaged people are, the greater
The brain controls the other body activities through______.
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