首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
We all know that we don’t get enough sleep. But how much sleep do we really need? Until about 15 years ago, one common theory wa
We all know that we don’t get enough sleep. But how much sleep do we really need? Until about 15 years ago, one common theory wa
admin
2015-10-21
77
问题
We all know that we don’t get enough sleep. But how much sleep do we really need? Until about 15 years ago, one common theory was that if you slept at least four or five hours a night, your cognitive performance remained intact; your body simply adapted to less sleep. But that idea was based on studies in which researchers sent sleepy subjects home during the day—where they may have sneaked in naps and downed coffee.
Enter David Dinges, the head of the Sleep and Chronobiology Laboratory at the Hospital at University of Pennsylvania, who has the distinction of depriving more people of sleep than perhaps anyone in the world. In what was the longest sleep-restriction study of its kind, Dinges and his lead author, Hans Van Dongen, assigned dozens of subjects to three different groups for their 2003 study: some slept four hours, others six hours and others, for the lucky control group, eight hours— for two weeks in the lab. Every two hours during the day, the researchers tested the subjects’ ability to sustain attention with what’s known as the psychomotor vigilance task, or P. V. T. , considered a gold standard of sleepiness measures. During the P. V. T. , the men and women sat in front of computer screens for 10-minute periods, pressing the space bar as soon as they saw a flash of numbers at random intervals. Even a half-second response delay suggests a lapse into sleepiness, known as a microsleep.
The P. V. T. is tedious but simple if you’ve been sleeping well. It measures the sustained attention that is vital for pilots, truck drivers, astronauts. Attention is also key for focusing during long meetings; for reading a paragraph just once, instead of five times; for driving a car. It takes the equivalent of only a two-second lapse for a driver to veer into oncoming traffic.
Not surprisingly, those who had eight hours of sleep hardly had any attention lapses and no cognitive declines over the 14 days of the study. What was interesting was that those in the four-and six-hour groups had P. V. T. results that declined steadily with almost each passing day. Though the four-hour subjects performed far worse, the six-hour group also consistently fell off-task. By the sixth day, 25 percent of the six-hour group was falling asleep at the computer. And at the end of the study, they were lapsing fives times as much as they did the first day. The six-hour subjects fared no better—steadily declining over the two weeks—on a test of working memory in which they had to remember numbers and symbols and substitute one for the other. The same was true for an addition-subtraction task that measures speed and accuracy. All told, by the end of two weeks, the six-hour sleepers were as impaired as those who, in another Dinges study, had been sleep-deprived for 24 hours straight—the cognitive equivalent of being legally drunk.
So, for most of us, eight hours of sleep is excellent and six hours is no good, but what about if we split the difference? What is the threshold below which cognitive function begins to flag? While Dinges’s study was under way, his colleague Gregory Belenky, then director of the division of neuroscience at the Walter Reed Army Institute of Research in Silver Spring, Md. , was running a similar study. He purposely restricted his subjects to odd numbers of sleep hours—three, five, seven and nine hours—so that together the studies would offer a fuller picture of sleep-restriction. Belenky’s nine-hour subjects performed much like Dinges’s eight-hour ones. But in the seven-hour group, their response time on the P. V. T. slowed and continued to do so for three days, before stabilizing at lower levels than when they started. Americans average 6. 9 hours on weeknights, according to the National Sleep Foundation. Which means that, whether we like it or not, we are not thinking as clearly as we could be.
Of course our lives are more stimulating than a sleep lab: we have coffee, bright lights, the social buzz of the office,all of which work as "countermeasures" to sleepiness. They can do the job for only so long, however. As Belenky, who now heads up the Sleep and Performance Research Center at Washington State University, Spokane, where Van Dongen is also a professor, told me about cognitive deficits:"You don’t see it the first day. But you do in five to seven days. "
And it’s not clear that we can rely on weekends to make up for sleep deprivation. Dinges is now running a long-term sleep restriction and recovery study to see how many nights we need to erase our sleep debt. But past studies suggest that, at least in many cases, one night alone won’t do it.
It can be learned from Paragraph Five that______.
选项
A、8-hour subjects fared the best among three groups
B、the 6-hour subjects began to decline in the middle of the study
C、half of the 6-hour subjects fell asleep at the computer
D、4-hour subjects were more impaired than 6-hour subjects
答案
A
解析
推断题。根据题干提示定位到第五段。该段主要讲述了丁格斯进行的一项最长睡眠限制期的研究结果。该段第一、二句指出,在为期14天的实验中,达到八小时睡眠的受试者几乎没有出现任何注意力分散或认知能力下降的现象,四小时组的受试者情况则很糟,还有六小时组参与者的表现也在走下坡路。[A]“八小时睡眠的受试者在三个组中进展最好”与之相符,是正确答案。该段第二句指出,四小时与六小时组的受试者的表现是日复一日逐步下降的,并不是到了实验中期才开始下降的,[B]“六小时组的受试者在实验进行到一半时表现开始下降”与文意不符,故排除;该段第四句指出,到了第六天时,六小时组中25%的人在电脑前进入了梦乡,[C]“六小时组的一半受试者都在电脑前睡着了”与文意不一致,故排除;[D]“四小时组受试者比六小时组受试者受损程度大”,文中并没有涉及二者之间的比较,故排除。
转载请注明原文地址:https://kaotiyun.com/show/ZXKO777K
0
专业英语八级
相关试题推荐
Oneofthefirstthingsthatshouldstrikeanyhalfobservantparentisthespeedandapparentaccuracyinwhichachildproceed
ThemoststrikingphoneticdifferencebetweenAmericanandBritishEnglishisthepronunciationof______inwords.
MarkTwain’sworksarecharacterizedbythefollowingexcept______.
WithafewhourstogobeforesouthSudanbecomesan【N1】______state,finalpreparationsareunderwayinthecapitalJuba.Theg
ForeignerssoughtsheltersinallthefollowingplacesEXCEPT
HowtoStudyEnglishinYourDream:theTheoryI.IntroductionA.ConnectionsamongEnglishstudy,imaginationanddreamB.Two
Whichofthefollowingisacentralvowel?
WhichofthefollowingisNOTthebackgroundinformationofapossibleattackonIran?
Accordingtothenewsitem,howmanyAmericansareunemployed?
Thatexperienceinfluencessubsequentbehaviorisevidenceofanobviousbutneverthelessremarkableactivitycalled"rememberi
随机试题
抗甲状腺药物治疗过程中,如出现症状缓解,而甲状腺肿大或突眼加重,应做以下处理
老年女性,不慎摔倒,左髋部着地,当即左髋剧痛,不能站立,急诊来院。检查见左下肢缩短,外旋畸形。其最可能的诊断是
某法院开庭审理一起民事案件,参加旁听的原告之夫李某认为证人王某的证言不实,便当场大声指责,受到法庭警告。李某不听劝阻,大喊“给我打”在场旁听的十多个原告方的亲属一拥而上,对王某拳打脚踢,法庭秩序顿时大乱。审判长予以制止,李某一伙又对审判长和审判员进行围攻、
以下不属于经济费用效益分析指标的是()。
如果进口合同不得不用硬币计价,而出口合同又不得不用软币计价了,那么,()。
基金份额持有人是( )。
出质人对质押权利占有的合法性,包括()
甲公司是一家上市公司,其中乙公司持有55%的股份;丙公司持有15%的股份;丁公司持有10%的股份。截至2005年底甲公司注册资本为8000万元,经审计的净资产额为12000万元。甲公司董事会由u名董事组成,其中董事A、董事B、董事C同时为乙公司董事,董事D
请将下列SQL语句的空缺部分补充完整。(1)假设已经创建好用户关系,现在想增加一个属性“个性签名”,类型为VARCHAR(60),请给出相关的SQL语句。(a);(2)假设已经创建好用户关系,下面是创建栏目关系的SQL语句
TheLostArtofListeningA)"Whywon’theevenlistentomyidea?""WhyamIcutoffbeforeIprovidethewholestory?"How
最新回复
(
0
)