题目内容
Sleeping
People who sleep for more than eight hours a night do not live as long as those who sleep for six hours, according to the biggest study yet into sleep patterns and mortality (死亡率).
Scientists have no explanation for the findings and do not know if they mean people who like a lie-in (睡懒觉) can extend their lives by sleeping less.
Although it is a common belief that sleeping for at least eight hours a night is vital for health and well-being, the six-year study involving more than 1.1 million Americans older than 30 found that those who slept for less than eight hours were far from doing themselves any long-term harm.
"Individuals who now average 6.5 hours of sleep a night can be reassured that this is a safe amount of sleep. From a health standpoint, there is no reason to sleep longer," said Daniel Kripke, a professor of psychiatry (精神病学) at the University of California, San Diego.
Dr. Kripke said, "We don't know if long sleep periods lead to death. Additional studies are needed to determine if setting your alarm clock earlier will actually improve your health."
The scientists, who were funded by the American Cancer Society, found that the best survival rates were among the men and women who slept for seven hours a night. Those who slept for eight hours were 12 per cent more likely to die during the six-year period of the study, when other factors such as diet and smoking were taken into account.
Even those who spent a mere five hours a night in bed lived longer than those who slept eight or more hours. However, an increasing death rate was found among those who slept for less than five hours.
Dr. Kripke said, "Previous sleep studies have indicated that both short- and long-duration (持续时间) sleep had higher mortality rates. However, none of those studies were large enough to distinguish the difference between seven and eight hours a night, until now."
More than one million Americans participated in the six-year study.
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Memory Class
Stan Field knows what age can do to a person's memory, and he's not taking any chances with his. He chooses his food carefully and gets plenty of exercise. He also avoids stress, coca cola and cigarette smoke. What's more, at breakfast each morning, the 69-year-old chemical engineer swallows a plateful of pills in the hope of boosting his brain power.
Michelle Arnove is less than half Field's age, but no less concerned about her memory. While working round the clock to finish a degree in film studies, the 33-year-old New Yorker had the alarming sensation that she had stopped retaining anything. "I couldn't even remember names," she says. "I thought, 'Oh no, I'm over 30. It's all downhill from here'." Besides loading up on supplements, Arnove signed up for a memory-enhancing course at New York's Mount Siani Medical Center. And when she got there, she found herself surrounded by people who were just as worried as she was.
For millions of Americans, and especially for baby boomers (生育高峰期出生的人), the demands of the Information Age conflict with a sense of declining physical power. "When boomers were in their 3os and 40s, they launched the fitness boom," says Cynthia Green, the psychologist who teaches Mount Sinai's memory class. "Now we have the mental-fitness boom. Memory is the boomers' new life-crisis Issue." And of course a major marketing opportunity. The demand for books and seminars has never been greater, says Jack Lannom, a longtime memory trainer whose weekly TV show, "Mind Unlimited," goes out to 33 million homes on the Christian Network. Anxious consumers are rushing to buy do-it-yourself programs and supplement makers are trying to sell everything but sawdust (木屑) as a brain booster.
But before you get out your checkbook, a few questions are In order. Does everyday forgetfulness signal declining brain function？ Is "megamemory" (超级记忆) a realistic goal for normal people？ And if you could have a perfect memory, would you really want it？ Until recently, no one could address those issues with much authority, but our knowledge of memory is exploding. New techniques are revealing how different parts of the brain, interact to preserve meaningful experiences. Biologists are trying to understand the underlying (潜的) chemical processes and neuroscientists (神经系统科学家) are discovering how age, stress and other factors can disrupt them. No one is close to finding the secret to perfect recall, but as you'll see, that may be just as well.
What does Stan Field take at breakfast？
债券的利率期限结构是指债券的到期收益率与到期期限之间的关系。 ()
上升楔形表示一个技术性反弹渐次增强的强市情况，常在跌市中的回升阶段出现。 ()
某公司年度后期进行增资扩股，使本公司的资产收益率、股东权益收益率指标下降，这表示该公司经营一定在走下坡路。 ()
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