睡觉

MOST people spend nearly a third of their lives asleep. Until the invention of the electric light bulb, they had little choice. Artificial light was dim and dear, so people rose with the lark and went to bed soon after dark. But for the past century or so, synthetic daylight has been available round the clock, and there is plenty to do at any time of day or night. For most people in rich countries, the 24-hour society has arrived. Sleeping at night, therefore, is no longer the default option. Many people decide that to make more room for other pursuits, they can do with less sleep.

大部分人一生中约三分之一的时间都在睡觉。电灯发明之前，人们别无选择。当时的人造光源既昏暗又昂贵，因此人们日出而作，日落而息。约一个世纪以来，人造灯光昼夜不息，并且无论白天黑夜，任何时间人们都有的是事情可做。对富裕国家的多数人来说，社会 24 小时运作的时代来临了。因此睡觉不再是夜晚的唯一选择。许多人决定，为了给其它追求腾出空间，他们可以少睡一点。

But is this a wise choice? Cutting back on sleep is a huge mistake, says a small but vocal band of sleep scientists, most of them in America. Their doyen, William Dement, founder and director of the Stanford University Sleep Research Centre, reckons that people on average now sleep one-and-a-half hours a night less than they did a century ago, at great cost to their health and safety (though others dispute this figure). He thinks we are living in a “sleep-sick society”.

但“少睡”的选择明智吗？一组人数不多但声势十足的睡眠科学家（大多在美国）认为，削减睡眠时间大错特错。他们的掌门人，斯坦福大学睡眠研究中心的奠基人兼主管威廉 - 德门认为，现在的人比一个世纪以前平均少睡一个半小时（尽管其他人对这个数字有异议），对健康和人身安全有巨大损害。他认为我们生活在一个“睡眠病态的社会”

To make their case, Dr Dement and his followers recite a litany of disasters in which a lack of sleep played a part.On the night the Exxon Valdez ran aground off Alaska in 1989, spilling 11m gallons of crude oil, the third mate in charge of the ship was acutely sleep-deprived. When the Space Shuttle blew up in 1986, killing all aboard, the NASA managers who authorised the launch, despite poor weather, had had little sleep the night before. The nuclear accidents at Chernobyl in 1986 and at Three Mile Island in 1979 each took place at night, and each involved serious errors of judgment by tired operators.

为了让他们的观点有理有据，德门博士和他的追随者们能背出一大堆由睡眠不足引起的灾难。 1989 年，在埃克森石油公司的“瓦尔迪兹”号在阿拉斯加搁浅并泄漏出 1100 万加仑原油的那个晚上，掌管轮船的三副睡眠严重不足。 1986 年，在令所有机组成员丧生的航天飞机爆炸事故中， NASA 的管理者前一晚上几乎没有睡觉，尽管天气恶劣还是批准了发射。 1986 年的切尔诺贝利核事故和 1979 年的三里岛核事故都发生在夜里，并且都出现了困倦的操作人员判断严重失误的情况。

On a more everyday level, road accidents are much more likely when drivers are sleepy. A report by the US National Commission on Sleep Disorders a few years ago found that driver fatigue contributed to over half of all vehicle accidents in America. And even if sleep deprivation does not result in death or injury, clinical studies show that it severely impairs performance—which ought to worry the boss of every underslept employee.

在平时生活方面，司机打瞌睡时，发生交通事故的可能性会大得多。美国国家睡眠障碍委员会（ US National Commission on Sleep Disorders ）几天前发布的一份报告显示，在美国，超过半数的车祸原因是疲劳驾驶。即使睡眠不足不导致受伤或死亡，临床研究指出，睡眠不足严重损害工作表现——这应该会让每位睡眠不足的员工的老板感到烦扰。

Yet although sleep takes up such a large proportion of our lives, we know little about it. Until fairly recently the theory was that people (like all higher animals) had to sleep to give body and mind a complete rest. But humans consume only slightly less energy when asleep than when simply resting, and we now know that their brains are highly active for some of the time that they are dozing. There are in fact two quite different types of sleep, REM (which stands for rapid eye movement) and non-REM, and they appear to meet different needs. In early man, non-REM sleep, when the body is relaxed and the brain relatively quiescent, may have served to ensure inactivity during times (usually at night) when lying low offered the best prospect of survival. REM sleep, on the other hand, when people dream and their brains are just as active as when awake, seems to play a part in developing and maintaining the brain. Babies and young animals spend much more time in REM sleep than adults, and older people spend progressively less. Recent theories link REM sleep to learning and memory.

尽管睡眠占据了我们人生中这么多时间，我们却知之甚少。直到非常近期，理论还认为人类（和所有高等动物一样）必须通过睡眠来给身体和大脑彻底的休息。但人类在睡觉时消耗的能量只比单纯休息时少一点点，并且我们现在知道，在睡眠的某些时段，人类的大脑处于高度兴奋状态。事实上人类有两种迥异的睡眠方式： REM （“眼球快速运动”之意）和非 REM 睡眠，并且两种睡眠方式分别满足了不同的需求。在人类早期，当蛰伏意味着生存机会最大时（通常是夜里），身体放松且大脑相对静止的非 REM 睡眠可能起到了确保身体静止不动的作用。另一方面，人会做梦并且大脑和清醒时一样活跃的 REM 睡眠可能起到了发展和维护大脑的作用。婴儿和小动物进行 REM 睡眠的时间比成人长得多，人们 REM 睡眠的时间也会随着年龄增大渐渐减少。近期的理论也把 REM 睡眠与学习记忆联系在一起。

We may not know exactly why we need to sleep, but it is clear that, at least for now, we cannot do without it. Sleep-deprivation experiments show that people become progressively less effective as they become increasingly tired. Preventing people from sleeping has been widely used as a form of torture that leaves the victims increasingly miserable, confused and suggestible, and may even kill them.

我们也许不清楚具体为什么我们需要睡觉，但可以明确的是，至少目前来说，我们还不能不睡觉。睡眠剥夺实验显示，随着人的困倦加深，效率会逐渐降低。不让人睡觉是广泛使用的折磨方法，能让受害者越来越痛苦、思维混乱并且容易受到他人影响，甚至还能杀死他们。

To try to understand sleep deprivation, ethical scientists prefer to experiment on rats. In one famous experiment, Allan Rechtschaffen and his colleagues at the University of Chicago placed rats on a turntable above a shallow bath of water. Every time they fell asleep, the turntable started tilting, forcing them to wake up and move to avoid falling into the water. Thus totally sleep-deprived, the rats invariably died within two or three weeks, having first become increasingly debilitated, developed sores, lost weight despite eating more than usual, and suffered a drop in body temperature. If the rats were allowed some non-REM sleep but no REM sleep, they lasted twice as long but still died eventually, after a period of sexualhy peractivity. A control group of rats that were exposed to the same stressful environment on the turntable, but were allowed some sleep of both sorts,survived.

为了研究睡眠丧失，有道德的科学家更喜欢用老鼠来做实验。在一个著名的实验中，亚伦 - 雷克萨芬和他在芝加哥大学的同事把老鼠放在一个转盘上，转盘下面是一缸浅水。只要老鼠一睡着，转盘就开始倾斜，迫使老鼠醒来并且移动，避免落入水中。依靠这种方式完全剥夺睡眠，老鼠毫无例外先是越来越衰弱，接着出现溃疡，吃得比平常多但体重下降、体温降低，两到三周内就死掉了。如果允许老鼠得到一些非 REM 睡眠但没有 REM 睡眠的话，他们能多活一倍的时间，但在一段性亢进时期之后，最终还是会死。控制组的老鼠也暴露在相同的转盘压力环境下，但是能获得两种类型的睡眠，存活下来了。

Exactly what caused the rats to die was not clear, but some of their symptoms pointed to a failure of their immune systems.Some scientists think sleep may help to keep the immune system functioning properly, pointing to the way people seem more liable to catch colds and flu after short nights or long flights.

到底是什么导致老鼠死亡尚不清楚，但是一些症状指出是它们的免疫系统失效。一些科学家认为，睡眠可能有助于保持免疫系统的正常运作，这就解释了为何人们在晚上只睡一小段时间或长途飞行后为何更容易患上伤寒和流感。

So how long can people safely go without snoozing? Chris Idzikowski, of Britain's University of Surrey, reckons it might take as much as a year of sleep deprivation to kill a human. Sufferers from a disorder called fatal familial insomnia, which prevents sleep, usually succumb within nine to 18 months.

那么人们多长时间不睡觉是安全的呢？英国萨里大学的克里斯 - 依德齐柯斯基认为，睡眠不足可能要持续一年才可致命。致命家族性失眠症能让患者无法睡眠，患者通常会在 9 到 18 个月内死亡。

Sleep-deprivation experiments on volunteers have stopped at a maximum of ten days, by which time the subjects were nearly asleep on their feet, and probably nodded off for frequent brief “micro-sleeps” without even knowing it. But most people would feel awful much sooner. When Charles Lindbergh made the first solo non-stop flight across the Atlantic in 1927, his main problem was staying awake. He foolishly had a short night before setting off; trying then to keep alert for 33½ hours in the air proved agonising. In his autobiography, he records how, nine hours into the flight, the desire to sleep became almost overwhelming:

对志愿者实行剥夺睡眠实验最多持续十天即止，此时实验对象几乎是站立着睡着了，频频点头进行短暂的“微睡眠”，自己却浑然不觉。但大部分人远不到 10 天就会感觉非常糟糕。 1927 年查尔斯 - 林德伯格完成人类首次驾机无间断飞越大西洋的过程中，他最大的难题就是保持清醒。起飞前夜他愚蠢地只是小睡一会，之后又试着在空中保持清醒 33 又二分之一小时，事实证明这令他极度痛苦。他在自传里写道，飞行 9 小时以后，他对睡眠的渴望几乎无法抵挡。

My eyes feel dry and hard as stones...Mymind clicks on and off...Sleep is winning. My whole body argues dully that nothing, nothing life can attain is quite so desirable as sleep.He did drop off several times and almost crashed once, but eventually got a “second wind” that carried him to Paris.

我感觉眼睛干涩，像石头一样硬…我的意识时断时续…睡眠正在乘胜追击。我全身都在迟钝地抗议，生命中没有任何东西比睡觉更令人向往了。 途中他的确睡着了好几次，有一次还差点坠机，但他“如梦方醒”，最终到达了巴黎。

Experiments show that when deprived of sleep, people become less adept at mathematical and verbal tasks, and their attention span and memory suffer. Even losing a couple of hours can make a measurable difference, particularly if the loss is repeated on subsequent nights. Many sleep scientists say this is building up a “sleep debt” that has to be repaid before the debtor can operate normally again.

实验显示，当人们睡眠不足时，数学计算和组织语言能力会下降，注意力涣散且记忆力变差。即使损失一到两个小时的睡眠也能看出明显差别，如果连续几晚损失睡眠的话情况尤甚。许多睡眠科学家认为，这样就建立起了“睡眠债”，负债者如果不补偿睡眠的话，身体就无法正常运作。

The standard tool for measuring fatigue isthe “multiple sleep latency test”, devised by Mary Carskadon of Brown University in the late 1970s. This is carried out in a dark, quiet room, where subjects are attached to various sensors, put to bed and asked to go to sleep.The test measures the time they take to drop off. They are then woken straight away. This procedure is repeated several times at intervals of a couple of hours. During daytime, well-rested people will take 20-25 minutes to nod off. If they take less than five minutes, they are probably seriously sleep-deprived or have a sleep disorder.

衡量疲倦的标准工具是布朗大学的玛丽 - 卡斯卡登在 1970 年代末期发明的“多重睡眠潜伏期试验”。该实验在黑暗安静的室内进行，实验者躺在床上，身体上连接多种传感器，然后试着入睡。该试验测量他们入睡所需的时间，接着马上把他们叫醒。该过程会重复若干次，每次间隔一两个小时。在白天，休息充足的人要过 20-25 分钟才打瞌睡。如果不到 5 分钟就睡着了，很可能是睡眠严重不足或患有睡眠紊乱。

Paradoxically, the more tired people are,the more confident they become that their reactions are perfectly normal. Such clouded judgment may not matter if they are selling life insurance (though their boss may think otherwise), but could be disastrous if they are driving alorry or controlling air traffic.

矛盾的是，人越是疲乏，他就越是觉得自己的反应正常得很。这种判断力被蒙蔽的情况，如果发生在推销人寿保险时倒无伤大雅（尽管老板不一定会这么想），但如果发生在驾驶卡车或控制空中交通的时候，后果将不堪设想。

“The death of each day's life, sorelabour's bath/ Balm of hurt minds, great nature's second course/ Chiefnourisher in life's feast”

“ ( 那清白的睡眠，把忧虑的乱丝编织起来的睡眠 ,) 给每天的生活划上了句号，给劳累一天浑身酸痛的体力劳动者洗去了一身的疲惫；为心神疲惫的人儿提供了慰藉，乃大自然不可或缺之步骤；为生命盛宴之头等佳肴。”

Some sleep scientists argue that sleep deprivation causes not only mental but also physical deterioration. Eve Van Cauter at the University of Chicago took a sample of fit young men and allowed them only four hours' sleep a night for a week. She found that their meta bolicrates changed in ways that made them more susceptible to obesity and diabetes,though once they were able to catch up on their sleep their metabolic rates returned to normal. Others dispute her findings, but nobody doubts that a reasonable amount of sleep is vital for health and well-being.

一些睡眠学家认为睡眠不足不只是让精神变差，身体也会变差。芝加哥大学的伊芙 - 范 - 科特用健康的男青年作为样本，让他们一周内每天仅睡 4 个小时。她发现实验者的新陈代谢率变得让他们更容易获得肥胖和糖尿病，然而，当他们能够恢复原来的睡眠时，代谢率也会回归正常水平。有人对她的发现提出质疑，但没人怀疑合理的睡眠时间对身体和健康而言非常重要。

But what is reasonable? There are no hard and fast answers. Everyone's needs are different. Women sleep a little more than men, and older people a little less than younger ones. Some do well on five or six hours; others need eight or nine. Adolescents need more sleep than adults, but often go to bed late and have to get up early for school, which perhaps explains why they are so moody.

那什么才是合理的睡眠呢？目前尚无现成和确定的答案。每人的需求不一样。女人比男人睡眠时间稍长一些，老年人比年轻人时间少一些。有些人只睡五六个小时也状况良好，其他人则需要八或九小时的睡眠。青少年比成年人需要的睡眠多一些，但经常很晚睡觉并得起早上学，这或许能解释他们为什么这么躁动不安。

Most people have a fairly good idea how much they need to be fully alert the next day, but may not get it because they are too busy doing other things. A common response is to economise on sleep during the working week and catch up at the weekend. In a 2002 “Sleep in America” poll of 1,000 adults across the United States, sponsored by the National Sleep Foundation, a lobbying group, respondents on average were found to sleep 6.9 hours on weekdays and 7.5 at weekends. Nearly a third of them said they needed at least eight hours to avoid feeling sleepy the next day. Just so,say the sleep-longer advocates: anything less, and you could be doing yourself serious harm.

许多人都对自己需要多长睡眠来保持第二天头脑清醒有相当不错的认识，但因为太过忙于其他事情，他们未必能获得足够的睡眠。一种普遍的应对办法是，工作日期间节省睡眠时间，留到周末再补上。 2002 年，来自美国各地的 1000 名成年人参加了游说组织“国家睡眠基金会（ National Sleep Foundation ）”的“睡在美国”投票活动，结果发现被调查者的平均年睡眠时间是 6.9 个小时，周末则为 7.5 小时。他们中约三分之一认为自己需要至少 8 小时的睡眠以避免第二天犯困。正因如此，赞成长时间睡眠的人说：睡眠一旦低于 8 个小时，你就对自己的健康造成了严重危害。

Not so, says Daniel Kripke of the University of California at San Diego. He re-analysed data from a big 1982 cancer study to examine the relationship beween sleep duration and subsequent mortality. The study had included the question: “On average, how many hours do you sleep each night?”, and had followed up the 1.1m respondents for six years.Dr Kripke found the highest survival rate in the group that reported sleeping for around seven hours a night. Those who slept a lot more or less than that were more likely to die. Surprisingly, the “risk” associated with sleeping too much appeared to be greater than with sleeping only a little. Dr Kripke is careful to point out that his work merely demonstrates an association, not a cause-and-effect relationship. It could be that ill-health causes odd sleeping patterns, rather than vice versa. But Dr Kripke argues that his work at least suggests that doctors should refrain from recommending eight hours to everyone; this may serve merely to worry people who can manage on six or seven.

加州大学圣地亚哥分校的丹尼尔 - 克里普克认为，事实并非如此。为了检验睡眠时间和死亡率的关系 , 他重新分析了一项 1982 年的大型癌症研究的数据。研究包含以下问题：“你平均每晚睡多长时间？”并且在六年内跟进调查了 110 多万名答复者。克里普克博士发现，声称自己每天睡 7 小时左右的一组生存率最高。睡眠时间比这个值高得多或低得多的人则更容易死亡。令人惊讶的是，看起来睡眠过剩的“风险”比稍睡少许来得更大。克里普克博士小心翼翼地指出，他的研究只是展示了一种联系，而不是因果关系。有可能是因为健康不佳才导致异常的睡眠方式，而不是异常的睡眠方式导致健康不佳。不过克里普克博士认为，他的研究至少指出了医生们不该再向每个人推荐 8 个小时的睡眠；否则只会让睡眠六七个小时就足够的人感到担忧。

Jim Horne and his colleagues at Loughborough University take a slightly different approach, distinguishing between essential “core” sleep and a non-essential extra component that is“pleasant to take”. Just as people will often eat and drink more than they need because they enjoy it, they will grab an extra hour's snooze because it gives them pleasure.

吉姆 - 霍恩和他在拉夫伯勒大学的同事们采用的方法略微不同，把必需的“核心”睡眠和非必需的“有则笑纳”的额外睡眠区分开。正如同人们常常因为享受而多吃多喝，他们也会因为愉悦感而多睡一个小时。

Dr Horne thinks that calling for nine hours a night is “absurd”; seven hours of uninterrupted sleep should be plenty for most people. It is “quality that counts, not quantity”, he says. If they still feel sleepy during the day, “let them nap”.

霍恩博士认为呼吁每晚九小时睡眠是“荒谬”的；对大多数人来说，不受打扰的 7 小时睡眠应该就足够了。他认为“重要的是质量，而不是数量”。“如果他们在白天感觉困倦，就让他们打个盹”。

In advocating naps, he is in good company. Several great men who claimed to need little sleep, including Napoleon, Edisonand Churchill, got by on their ability to nod off briefly whenever they had the chance. Many people in Latin countries still take siestas, though modern working patterns discourage the habit. Sleep scientists say that short “powernaps” can be particularly useful for keeping people alert if taken before, during or after a period of sleep loss, such as a night shift. David Dinges, at the University of Pennsylvania, found that “prophylactic” naps could improve performance for hours afterwards. Most researchers say that to be most effective, naps should be short, say half an hour. If they last longer, the nappers will fall into a deep sleep and take too long to wake up again (a condition called “sleep inertia”). For most people, napping on the job might create the wrong impression, but a few enlightened companies in America and Japan have introduced nap rooms in the hope of promoting greater post-snooze productivity.

在倡导小睡方面，他不是一个人在战斗。有不少伟人 ( 包括拿破仑、爱迪生和丘吉尔 ) 都声称自己几乎不需要睡觉，凭借一有机会就打盹小睡的能力也凑合着过来了。许多拉丁国家的人仍有午睡习惯，尽管现代的工作模式不鼓励这种习惯。睡眠科学家声称，如果在睡眠不足的时段（例如倒夜班）之前、期间或之后进行短时间的“强效睡眠”，也许能非常有助于保持清醒。宾夕法尼亚大学的大卫 - 丁吉斯发现，“预防性”的小睡能有助于提高之后几个小时的工作表现。大部分研究者都声称，要想效率最高，睡眠时间要短，比如说半个小时。如果睡眠持续时间超过半小时，睡觉者会进入深层睡眠，并且醒来需要的时间过长（这种状况被称为“睡眠惯性”）。对于大多数人来说，工作时间打瞌睡可能给人不好的印象，但少数开明的美国和日本公司引进了瞌睡室，希望员工能在睡醒后更好地提高工作效率。

If people are not getting enough sleep, the blame is usually laid on quasi-voluntary factors such as work patterns (shift work, long working hours), modern travel (jetlag) and lifestyle choices (too much partying, having young children). However, much sleep deprivation is involuntary. Many people suffer from potentially dangerous sleep disorders that often remain unrecognised because doctors know scandalously little about them.

如果人们没有得到充足的睡眠，借口通常是半主动因素，比如工作模式（换班，长时间工作），现代旅行（时差）和生活方式的选择（社交过多，抚育幼子）。然而，许多睡眠损失是非自愿的。许多人有患上睡眠紊乱的潜在风险，而且这种风险常常未被发现，因为可耻的是，医生对这方面的了解甚少。