Contrary to popular belief, people who sleep six to seven hours anight live longer, and those who sleep eight hours or more dieyounger, according to the latest study everconducted on the subject. The study, which tracked the sleepinghabits of 1.1 million Americans for six years, undermines theadvice of many sleep doctors who have long recommended that peopleget eight or nine hours of sleep every night。
"There's an old idea that people should sleep eight hours a night,which has no more scientific basis than the gold at the end of therainbow," said Daniel Kripke, a professor of psychiatry at theUniversity of California at San Diego who led the study, publishedin a recent issue of the Archives of General Psychiatry. "That's anold wives' tale.
The study wasnot designed to answer why sleeping longer may be deleterious orwhether people could extend their life span by sleeping less。
But Kripkesaid it was possible that people who slept longer tended to sufferfrom sleep apnea, a condition where impaired breathing puts stresson the heart and brain. He also speculated that the need for sleepwas akin to food, where getting less than people want may be betterfor them。
The study quickly provoked cautions and criticism, with some sleepexperts saying that the main problem in America's sleep habits wasdeprivation, not sleeping too much。
"None of thissays sleep kills people," said Daniel Buysse, a University ofPittsburgh psychiatrist and the immediate past president of theAmerican Academy of Sleep Medicine. 匹兹堡大学精神病学家，即美国睡眠医学会刚刚离任的前任会长Daniel Buysse说：“这决不是说睡眠导致死亡。”
"You should sleep as much as you need to feel awake, alert andattentive the next day," Buysse added. "I'm much more concernedabout people short-changing themselves on sleep than peoplesleeping too long."
Sleeplessnessproduces a variety of health consequences that were not measured inthe study, critics said。
"The amount ofsleep you get impacts how alert you are, your risk for accidents,how you perform at work and school," said James Walsh, president ofthe National Sleep Foundation, a non-profit that advocates forbetter sleep habits. "There's much more to life than how long youlive."
The study used data from an extensive survey conducted by theAmerican Cancer Society from 1992 to 1998. Women sleeping 8, 9 and 10 hours a night had 13 percent,23 percent and 41 percent higher risk of dying, respectively, thanthose who slept 7 hours, the study found。
Men sleeping 8, 9 and 10 hours anight had 12 percent, 17 percent and 34 percent greater risk ofdying within the study period。
By contrast,sleeping five hours a night increased the risk for women by only 5percent, and for men, by 11 percent. Among people who slept justthree hours a night, women had a 33 percent increase in death, andmen had a 19 percent increase, compared with those who slept sevenhours。
Kripke, the new study's leader, pointed out that relatively fewpeople slept so little--1 in 1,000--where as almost half of allpeople slept eight hours or more。来源：考试大
The study also found that taking a sleeping pill every dayincreased the risk of death by 25 percent。
He recommendedthat people should not routinely take pills to get eight hours ofsleep. While acknowledging that the sleeping pills used from 1992to 1998 were not the same pills being used today, Kripke said,"without data showing that contemporary pills are safe, these dataprovide the best information about whether sleeping pills are safefor long-term use."
Kripke, whose study was funded by federal tax dollars, saiddoctors' recommendations that everyone get eight hours of sleep anight may have been partly influenced by the drug companies thatmake sleeping pills. He cited a report from a public relations firmrepresenting the medicine Ambien, which gave money to the NationalSleep Foundation to alert people about an insomnia "public healthcrisis" as part of a marketing campaign。
Both Buysseand Walsh have served as paid consultants to makers of sleepingpills, but both denied being influenced by that role. Walsh saidmost researchers in the field had accepted consulting fees from thecompanies, because "99 percent of the funding to support this typeof research is from pharmaceutical companies."
Buysse, who wrote an editorial accompanying Kripke's article, saidmore research was needed to pin down exactly what the connectionwas between sleep and the risk of death. The study relied onpeople's own reports of their sleeping habits, which can be faulty.When people are asked how long they sleep, they usually report howlong they spend in bed, Buysse said. Buysse为Kripke的文章配发了一篇社论，他说有必要做进一步的研究以确定睡眠和死亡率之间究竟是什么联系。他说这一研究靠的是人们对自己睡眠习惯的汇报，而这有可能会出错。当问人们睡多长时间时，他们通常汇报的是他们在床上呆的时间。
That couldmean that people who reported sleeping eight hours were reallysleeping around seven and a half hours, which would bring them intothe study's lower risk category. Buysse also disagreed that sleepwas like food, arguing that while people can restrict sleep, theycannot "choose" to sleep longer。
DonaldBliwise, a psychologist at Emory University, in Atlanta, saidstudies had shown that when people were allowed to sleep howeverlong they wanted, without cues from alarm clocks and watches, theyoften slept 14 to 15 hours a day for the first few days。
"Everyone,"Bliwise said, "walks around somewhat sleep deprived."