不管怎樣，請保持睡眠八小時

At this point we should all know that we need to get eight hours of sleep per night. Any less and you’re functioning below normal. But what about more? Is it possible to get too much rest?

我們都應(yīng)該知道我們需要每晚睡八小時，少了，日常機能就會低于正常水平。但是睡多了呢?有可能得到更多休息嗎?

A new study suggests that yes, getting nine or more hours of sleep per night might also be unhealthy. Researchers from around the world gathered data from 116,632 people in 21 countries, each of whom they followed for about 7.8 years to see whether the amount they slept correlated with their overall risk of mortality (their likelihood of dying during the course of the study). They published their results in the European Heart Journal, which showed what epidemiologists call a J-shaped curve. The phenomenon refers to there being a point in a graph of mortality where the risk is minimized. In this case, that’d be right around eight hours of sleep. As you head down on the chart toward fewer hours of sleep, the risk of death increases for a whole host of reasons, but there’s also a rising risk as you increase the amount of sleep. And they’re not the only ones to find the J-shape. Other studies have also found that people who get nine or more hours of rest each night seem to have higher rates of mortality,

一項新研究指出，每晚睡9小時或更多對健康也是有害的。來自世界各地的研究人員收集了來自21個國家的116632人的數(shù)據(jù)，他們每個人都被追蹤了大約7、8年，看他們的睡眠量是否與他們的整體死亡風(fēng)險(他們在研究過程中死亡的可能性)相關(guān)。他們將結(jié)果發(fā)表在《歐洲心臟雜志》上，結(jié)果顯示了流行病學(xué)家所稱的“J形”曲線。這種現(xiàn)象現(xiàn)實在死亡風(fēng)險最小化的地方有一個點。在這種情況下，這個點是大約8小時的睡眠。當(dāng)你在圖表上往更少的睡眠時間看去時，死亡的風(fēng)險會因各種原因而增加，但隨著你增加睡眠量，風(fēng)險也會增加。而且受試者數(shù)據(jù)并不是唯一顯示J形的，其他研究還發(fā)現(xiàn)，每晚睡九小時或更長時間的人似乎死亡率更高。

But that doesn’t necessarily mean that more sleep is causing more death. Sometimes a curve is J-shaped because of some other confounding factor.

但這并不一定意味著更多的睡眠會導(dǎo)致更高的死亡風(fēng)險，某些其他混雜因素也會讓曲線呈J形。

Think of an adult you know who sleeps 10 hours a day. Is that a healthy person? Probably not. Experts like Matthew Walker, the director of the sleep and neuroimaging lab at the University of California, Berkeley, have discussed how various diseases and chronic ailments might prompt someone to sleep more yet also put them at higher risk of death. He discusses studies like this one in his book, Why We Sleep, in which he points out that “should you explore those studies in detail, you learn that the causes of death in individuals sleeping nine hours or longer include infection (e.g., pneumonia) and immune-activating cancers.” Serious illnesses like these prompt a person to sleep more, he points out, and thus “the illusion created is that too much sleep leads to an early death, rather than the more tenable conclusion that the sickness was just too much despite all efforts to the contrary from the beneficial sleep extension.”

想想你認識的盆友里每天睡10個小時的人，這是一個健康的人嗎?可能不是。加州大學(xué)伯克利分校睡眠和神經(jīng)影像實驗室主任Matthew Walker討論了各種疾病和慢性疾病如何促使人睡得更多，同時也使他們面臨更高的死亡風(fēng)險。他在他的書《我們?yōu)槭裁匆X》中討論了這樣的研究，他在其中指出，“如果詳細探討這些研究，會發(fā)現(xiàn)睡眠9小時或更長時間的人的死亡原因包括感染(如肺炎)。像這樣的嚴重疾病促使一個人睡得更多，因此會讓人覺得，過多的睡眠會導(dǎo)致早逝，而不是更為可靠的結(jié)論，盡管有益的睡眠讓你更健康，但是疾病帶來的負面影響太多了。“

The researchers who ran this most recent study were well aware of this criticism, and so went to impressive lengths to try to prevent the confounding factor of illness. They tried eliminating people who had any symptoms that might hint at underlying disease from the analysis, as well as those who already had a diagnosed illness, and found similar results. That could be a sign that there really is something about sleeping more that’s unhealthy for us. But it’s also important to note that even these researchers note “causality cannot be definitively proven from this or other observational studies.” Observational studies are great for looking at large populations on whom you can’t do detailed sleep analyses, but they’re simply not able to draw conclusions about whether one factor caused another.

進行這項最新研究的研究人員非常清楚這種批評，因此為了防止混淆的疾病因素，他們付出了巨大的努力。他們試圖從分析中消除那些可能包含潛在疾病癥狀的人，以及那些已經(jīng)確診患病的人，并發(fā)現(xiàn)了類似的結(jié)果。這可能是一個跡象，表明確實存在一些關(guān)于睡眠的誤解，這對我們來說是不健康的。但同樣重要的是，即使這些研究人員也注意到“這種或其他觀察性研究無法明確證實因果關(guān)系。”觀察性研究非常適合觀察無法進行詳細睡眠分析的大群體，但它們只是簡單的觀察，無法得出關(guān)于一個因素是否導(dǎo)致另一個因素的因果性的結(jié)論。

To figure that out, you need to do some kind of randomized study. That would mean prescribing groups to sleep a certain amount for many years and following them to see what happened, which is probably not feasible. Barring that, researchers would need to figure out a plausible mechanism by which sleep would increase risk of death. Cigarettes, for example, were never prescribed to people who were then followed in lengthy, randomized studies. Scientists had to do other, more clever experiments to figure out how the components of cigarettes were impacting the human body and use that evidence to draw conclusions from observational data.

要弄明白這一點，需要做一些隨機研究。這意味著受試群體要睡足一定量多年并跟蹤他們，看看發(fā)生了什么，這大概是不可行的。除此之外，研究人員需要找出一種合理的機制證明睡眠過多會增加死亡風(fēng)險。例如，吸煙從未納入對研究的影響。科學(xué)家們不得不做其他更巧妙的實驗來弄清楚煙草成分如何影響人體，并利用這些證據(jù)從觀察數(shù)據(jù)中得出結(jié)論。

So far, though, Walker writes that “no biological mechanisms that show sleep to be in any way harmful have been discovered.” That doesn’t mean they won’t be in the future—maybe we will find a mechanism. It’s just that right now it’s not clear how 9.5 hours of sleep versus 8 would negatively impact a person.

然而，到目前為止，Walker寫道“沒有發(fā)現(xiàn)任何顯示睡眠有害的生物機制。”這并不意味著將來不會 - 也許我們會找到一種機制。但現(xiàn)在就是這樣，目前尚不清楚9.5小時的睡眠與8小時會對一個人產(chǎn)生負面影響。

Statistics would also suggest that far more Americans should be concerned with not getting enough sleep than with getting too much. A 2013 Gallup poll showed that 40 percent of Americans regularly sleep six hours or less per night, whereas only five percent get nine-plus hours. Part of the problem with chronic sleep deprivation is that you don’t realize how sleep-deprived you are while you’re sleep-deprived. Researchers have tested this by monitoring people in sleep labs and having them sleep eight hours per night, then six hours another night, and having them take the same test after each. When asked how they think they did after only sleeping for six hours, people say they did great, probably just as well as they did when fully recharged. In reality, they did significantly worse. They just didn’t realize it.

統(tǒng)計數(shù)據(jù)還表明，更多的美國人應(yīng)該關(guān)注的是睡眠不足而不是過多。2013年蓋洛普民意調(diào)查顯示，40%的美國人每晚經(jīng)常睡6個小時或更少，而只有5%的人每天睡9個小時。慢性睡眠剝奪的部分問題在于，你沒有意識到在睡眠不足時你的睡眠不足。 研究人員通過監(jiān)測睡眠實驗中的人并讓他們每晚睡8小時，然后每晚睡6小時，并讓他們在每次睡眠后進行相同的測試。當(dāng)被問及他們認為他們只睡了六個小時之后他們是怎么想的時候，人們說他們感覺很好，可能和完全睡飽一樣好。但實際上，他們的表現(xiàn)要差得多，而他們只是沒有意識到這一點。

So if you’re one of those people who claims they only need six hours, don’t use this study to prove how it’s just as bad to get too much sleep. The jury is still out on how surplus sleep could hurt you, but it is most definitely in on how harmful it is to be chronically sleep-deprived. Aim for eight hours every single night, regardless of how much you think you need. And if you’re consistently sleeping more than nine or ten hours a night, go see a doctor to make sure you don’t have some underlying condition or a sleep disorder. You may be perfectly fine, but you never know.

因此，如果你是那些聲稱只需要六個小時的人之一，那么就不要用這項研究來證明睡眠太多也是如此糟糕。研究團隊仍然沒有搞清楚多余的睡眠會對你造成什么傷害，但長期睡眠不足絕對會對你有很大的傷害。無論你認為自己需要多少睡眠，請每晚嘗試睡8小時。如果你每晚睡眠時間超過九或十個小時，那就去看醫(yī)生，確保你沒有某些潛在的病癥或睡眠障礙。你可能感覺很好，但你永遠不知道是不是這樣。