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How long can we stay awake?

It’s surprising how we spend our lives. Reach your 78th birthday and according to some back-of-the-envelope calculations, you will have spent nine of those years watching television, four years driving a car, 92 days on the toilet, and 48 days having sex.


But when it comes to time-consuming activities, there’s one that sits head and shoulders above them all. Live to 78, and you may have spent around 25 years asleep. In an effort to claw back some of that time it’s reasonable to ask: how long can we stay awake – and what are the consequences of going without sleep?


Any healthy individual planning to find out through personal experimentation will find it tough going. "The drive to sleep is so strong it will supersede the drive to eat," says Erin Hanlon, an assistant professor at the University of Chicago's Sleep, Metabolism and Health Centre. "Your brain will just go to sleep, despite all of your conscious efforts to keep it at bay."

任何一个想要通过亲身实验来找出答案的健康人,都会发现这是一段极其痛苦的经历。“睡眠的欲望如此强烈,甚至超过了进食的欲望。”芝加哥大学睡眠、新陈代谢和健康中心助理教授艾琳·翰隆(Erin Hanlon)说,“尽管你调动所有的意识来抗拒睡眠,但大脑却已经昏昏欲睡。”

Why sleep at all?


Exactly why the urge to sleep is so strong remains a mystery. "The exact function of sleep is still to be elucidated," says Hanlon. She adds, however, that there is something about sleep that seems to “reset” systems in our bodies. What’s more, studies have shown that routine, adequate sleep promotes healing, immune function, proper metabolism, and much more – which is maybe why it feels good to arise refreshed after a serious snooze.


On the flip side, insufficient slumber has been linked to greater risks of diabetes, heart issues, obesity, depression and other maladies. To avoid those latter outcomes, we are wracked with uncomfortable sensations when we burn the midnight oil: we lack energy, feel groggy, and find that our heavy eyelids press on aching eyes. As we continue to fight off sleep, our ability to concentrate and form short-term memories slackens.


If we ignore all these side effects and stay up for days on end, our minds become unhinged. We get moody, paranoid, and see things that aren’t really there. "People start to hallucinate and go a bit crazy," says Atul Malhotra, the Director of Sleep Medicine at the University of California, San Diego. (Long-haul truckers have an evocative term for this hallucinatory phenomenon: "seeing the black dog". When a shadowy apparition appears on the roadway, so the advice goes, it's time to pull the lorry over.)

如果你对这些不良影响视而不见,仍然坚持熬夜工作,思维就会错乱。我们会变得喜怒无常、妄想偏执,甚至会看到根本不存在的东西。“人们开始产生幻觉,变得有些疯狂。”加州大学圣迭戈分校睡眠医学系主任阿图尔·马尔霍特拉(Atul Malhotra)说。(对于这种幻觉,长途卡车司机有一句行话:“看见黑狗。”当路上出现这样的黑影时,就该停车休息了。)

Many studies have documented the body's parallel decline during sleep deprivation. Stress hormones such as adrenaline and cortisol increase in the blood, in turn elevating blood pressure. Meanwhile, heart rhythms get out of whack and the immune system falters, says Malhotra. Sleep-deprived people accordingly feel anxious and are likelier to come down with an illness.


Still, all the havoc wreaked by a bout of insomnia or a few all-nighters does not seem permanent, disappearing after solid shuteye. "If there's any damage, it's reversible," says Jerome Siegel, a professor at the Centre for Sleep Research at the University of California, Los Angeles.

不过,连夜的失眠或熬夜造成的各种破坏似乎都是暂时的。只要美美地睡上一觉,这些症状都会消失。“即使有什么伤害,也是完全可以修复的。”加州大学洛杉矶分校睡眠研究中心教授杰洛米·赛格尔(Jerome Siegel)说。

When the curtain never falls


But what if sleep never can come? A rare genetic disease called Fatal Familial Insomnia provides one of the starkest pictures of the consequences of extreme sleeplessness.

但如果永远不睡觉会怎么样?有一种名为致死性家族性失眠症(Fatal Familial Insomnia)的遗传疾病,让我们得以了解这种极端情况下最严酷的后果。

Only about 40 families worldwide have FFI in their gene pools. A single defective gene causes proteins in the nervous system to misfold into "prions" that lose their normal functionality. "Prions are funny-shaped proteins that screw these people up," says Malhotra. The prions clump in neural tissue, killing it and forming Swiss cheese-like holes in the brain (which is exactly what happens in the best-known human prion disorder, Creutzfeldt-Jakob disease). One area that is particularly badly affected in people with FFI is the thalamus, a deep brain region that controls sleep. Hence the debilitating insomnia.


An afflicted individual suddenly goes days on end without rest and develops weird symptoms such as pinpoint pupils and drenching sweats. After a few weeks, the FFI victim slips into a sort of pre-sleep twilight. He or she appears to be sleepwalking and exhibits those jerky, involuntary muscle movements we sometimes have when falling asleep. Weight loss and dementia follow, and eventually, death.


Still, sleeplessness per se is not thought to be the lethal agent, because FFI leads to widespread brain damage. "I don't think it is sleep loss that kills these individuals," says Siegel. Similarly, the oft-used torture tactic of depriving human prisoners of sleep is not known to have summarily caused anyone to die (although they will still suffer horribly).


Along these lines, animal sleep deprivation experiments provide more evidence that a lack of sleep in its own right might not be deadly, but what prompts it may well be.


Studies by Allan Rechtschaffen at the University of Chicago in the 1980s involved placing rats on discs above a tray of water. Whenever the rat tried dozing off, as revealed by changes in measured brain waves, the disc would rotate and a wall would shove the rat towards the water, startling it back awake.

芝加哥大学的阿兰·雷切斯查芬(Allan Rechtschaffen)在20世纪80年代进行的研究,就将大鼠放在了一个盘子上,下面则是一盆水。科学家通过脑电波监测大鼠的困意,每当它们打瞌睡时,盘子都会旋转,导致大鼠被墙壁推入水中,使之保持清醒。

All rats died after about a month of this treatment, though for unclear reasons. Most likely, it was the stress of being awoken – on average a "thousand times a day" says Siegel – that did the rats in, wearing down their bodily systems. Among other symptoms, the rats exhibited body temperature dysregulation and lost weight despite an increased appetite.


"That’s the problem in interpreting sleep studies in humans and animals: You can't thoroughly deprive a person or an animal of sleep without their cooperation and not impose a fair amount of stress," says Siegel. If death occurs, "the question is, 'is it the stress or the sleep loss?' It's not an easy distinction."


Wake up! Wake up!


All of this may well put most people off exploring the limits of our capacity to go without sleep, but the question remains: how long can we stay awake? The most widely cited record for voluntarily staving off sleep belongs to Randy Gardner, at the time a 17-year-old high school student in San Diego, California. For a science fair project in 1964, Gardner did not hit the hay for 264 hours straight, or just over 11 days, according to scientists who monitored him towards the end of his vigil. Numerous other, less credible accounts abound, including one of a British woman in 1977 who won a competition to continuously rock in a rocking chair (presumably by a landslide) by doing so for 18 days.

正因如此,多数人可能都无法探索人类究竟能够连续多长时间不睡觉,但我们还是不禁要问:人类究竟能坚持多长时间不睡觉?最广为人知的自愿睡眠剥夺记录属于兰迪·加德纳(Randy Gardner),他创造纪录时只有17岁,还在加州圣迭戈一所高中就读。根据当时负责监督他的科学家回忆,1964年,加德纳参加一个科学展览项目时创造了连续264小时(也就是超过11天)不睡觉的记录。还有很多人提到了其他一些可信度较低的纪录,包括一位英国女性1977年在连续摇椅竞赛中获胜,整整坚持了18天(估计她的这个成绩遥遥领先其他选手)。

Overall, the jury is out on just how long a human could ever stay awake, but perhaps that's a good thing. Acknowledging the injury people might cause to themselves through intentional sleep deprivation, the Guinness Book of Records stopped keeping track of this particular superlative last decade.

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