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More Than 8 Hours Sleep Too Much of a Good Thing
1 Although the dangers of too little sleep are widely known,new research suggests that people who sleep too much may also suffer the consequences.
2 Investigators at the University of California in San Diego found that people who clock up 9 or 10 hours each weeknight appear to have more trouble falling and staying asleep,as well as a number of other sleep problems,than people who sleep 8 hours a night. People who slept only 7 hours each night also said they had more trouble falling asleep and feeling re-freshed after a night's sleep than 8-hour sleepers.
3 These findings,which DL Daniel Kripke reported in the journal Psychosomatic Medicine,demonstrate that people who want to get a good night's rest may not need to set aside more than 8 hours a night.He added that“it might be a good idea” for people who sleep more than 8 hours each night to consider reducing the amount of time they spend in bed,but cau-tioned that more research is needed to confirm this.
4 Previous studies have shown the potential dangers of chronic shortages of sleep一for instance,one report demonstrated that people who habitually sleep less than 7 hours each night have a higher risk of dying within a fixed period than people who sleep more.
5 For the current report,Kripke reviewed the responses of 1,004 adults to sleep ques-tionaires,in which participants indicated how much they slept during the week and whether they experienced any sleep problems. Sleep problems included waking in the middle of the night,arising early in the morning and being unable to fall back to sleep,and having fatigue interfere with day-to-day functioning.
6 Kripke found that people who slept between 9 and 10 hours each night were more like-ly to report experiencing each sleep problem than people who slept 8 hours. In an interview, Kripke noted that long sleepers may struggle to get rest at night simply because they spend too much time in bed. As evidence,he added that one way to help insomnia is to spend less time in bed.“It stands to reason that if a person spends too long a time in bed,then they'll spend a higher percentage of time awake.”he said.
Paragraph 2______
A: Kripke's Research
B: Dangers of Habitual Shortages of Sleep
C: Criticism on Kripke's Report
D: A way of Overcoming Insomnia
E: Sleep Problems of Long and Short Sleepers
F: Classification of Sleep Problems
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Less Is More
It sounds all wrong—drilling holes in a piece of wood to make it more resistant to knocks. But it works because the energy from the blow gets distributed throughout the wood rather than fo-
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第二篇
Electric Backpack
Backpacks are convenient. They can hold your books,your lunch,and a change of clothes,leaving your
hands free to do other things.Someday,if you don't mind carrying a heavy load,your backpacks might also
power your MP3 player,keep your cell phone running,and maybe even light your way home.
Lawrence C.Rome and his colleagues from the University of Pennsylvania in Philadelphia and the
Marine Biological Laboratory in Woods Hole,Mass.,have invented a backpack that makes electricity from
energy produced while its wearer walks.In military actions,search-and-rescue operations,and scientific field
studies,people rely increasingly on cell phones,global positioning system(GPS)receivers,night-vision
goggles,and other battery-powered devices to get around and do their work. The backpack's electricity-generating
feature could dramatically reduce the amount of a wearer's load now devoted to spare batteries,report Rome
and his colleagues in the Sept.Science.
The backpack's electricity-creating powers depend on springs used to hang a cloth pack from its metal
frame.The frame sits against the wearer's back,and the whole pack moves up and down as the person
walks.A gear mechanism converts vertical movements of the pack to rotary motions of an electrical generator,
producing up to 7.4 watts.
Unexpectedly tests showed that wearers of the new backpack alter their gaits in response to the pack's
oscillations,so that they carry loads more comfortably and with less effort than they do ordinary backpacks.
Because of that surprising advantage,Rome plans to commercialize both electric and non-electric versions of
the backpack.
The backpack could be especially useful for soldiers,scientists,mountaineers,and emergency workers
who typically carry heavy backpacks.For the rest of us,power-generating backpacks could make it possible to
walk,play video games,watch TV,and listen to music,all at the same time.Electricity-generating packs
aren't on the market yet,but if you do get one eventually,just make sure to look both ways before crossing
the street!
According to Paragraph 4,what does Rome plan to do?
A:To make the backpack more comfortable for the wearer.
B:To put the backpack on the market.
C:To test the advantage of the backpack.
D:To promote the backpack in a newspaper or on television.