每天8小時不是必需睡眠?大綱

The idea that we should sleep in eight-hour chunks is relatively recent. The world’s population sleeps in various and surprising ways. Millions of Chinese workers continue to put their heads on their desks for a nap of an hour or so after lunch, for example, and daytime napping is common from India to Spain.

人應連睡八小時，這是相對較新的理念。在這個世界上，人們睡覺的方式千姿百態、令人驚訝。比如在中國，現在仍然有上百萬人每天吃完午飯後，要趴在桌上打一個小時的盹。在從印度到西班牙的國家裏，午睡都司空見慣。

One of the first signs that the emphasis on a straight eight-hour sleep had outlived its usefulness arose in the early 1990s, thanks to a history professor at Virginia Tech named A. Roger Ekirch, who spent hours investigating the history of the night and began to notice strange references to sleep. A character in the “Canterbury Tales,” for instance, decides to go back to bed after her “firste sleep.” A doctor in England wrote that the time between the “first sleep” and the “second sleep” was the best time for study and reflection. And one 16th-century French physician concluded that laborers were able to conceive more children because they waited until after their “first sleep” to make love. Professor Ekirch soon learned that he wasn’t the only one who was on to the historical existence of alternate sleep cycles. In a fluke of history, Thomas A. Wehr, a psychiatrist then working at the National Institute of Mental Health in Bethesda, Md., was conducting an experiment in which subjects were deprived of artificial light. Without the illumination and distraction from light bulbs, televisions or computers, the subjects slept through the night, at least at first. But, after a while, Dr. Wehr noticed that subjects began to wake up a little after midnight, lie awake for a couple of hours, and then drift back to sleep again, in the same pattern of segmented sleep that Professor Ekirch saw referenced in historical records and early works of literature.

在20世紀90年代初，第一次有人指出連續八小時睡眠是個過時的概念，提出這個想法的是弗吉尼亞理工學院(Virginia Tech)的歷史學教授A·羅傑·埃克奇(A. Roger Ekirch)，他花了大量時間翻查關於夜晚的史料，結果發現古人在談到睡眠時會做出一些奇怪的表述。比方說，在《坎特伯雷故事集》(Canterbury Tales)裏，當中的一個人物決定在睡了“第一覺”後回到牀上再躺一下。而英國的一位醫生寫道，在“第一覺”和“第二覺”中間的這段時間，用於學習和思考再合適不過。還有一位16世紀的醫生認爲，做苦力的人之所以能多生幾個孩子，是因爲他們要等睡過了“第一覺”後再做愛。埃克奇教授很快發現，他不是唯一一個發現交替睡眠週期由來以久的人。當時在馬裏蘭州貝塞斯達的美國國家心理健康研究院(National Institute of Mental Health)擔任精神病學專家的托馬斯·A·韋爾(Thomas A. Wehr)進行了一項實驗，參與者不得使用人造光源。由於沒有了電燈、電視或電腦這些產品的照明與干擾，參與試驗的人只能在夜裏呼呼大睡——至少一開始是這樣的。但過了一陣子，到了午夜過後，韋爾發現參與者紛紛醒來，他們在牀上醒着躺了幾個鐘頭，然後重新睡去，這樣斷斷續續的睡眠週期，與埃克奇教授從史料和早期文獻中發現的例證是一樣的。

It seemed that, given a chance to be free of modern life, the body would naturally settle into a split sleep schedule. Subjects grew to like experiencing nighttime in a new way. Once they broke their conception of what form sleep should come in, they looked forward to the time in the middle of the night as a chance for deep thinking of all kinds, whether in the form of self-reflection, getting a jump on the next day or amorous activity. Most of us, however, do not treat middle-of-the-night awakenings as a sign of a normal, functioning brain.

看起來，如果得到一個遠離現代生活的機會，我們的身體能夠自然而然地適應片斷式的睡眠節奏。參加實驗的人漸漸喜歡上了用一種新的方式來感受夜晚。一旦他們打破了關於睡眠形式的既有觀念，就會期待着能趁着午夜時分來進行沉思，不管他們是用這段時間來進行反思、爲第二天做好準備、還是想感情方面的事情。不過，我們中的大部分人都覺得在子夜時分醒來，不能算是大腦運行如常的信號。

Robert Stickgold, a professor of psychiatry at Harvard Medical School, proposes that sleep — including short naps that include deep sleep — offers our brains the chance to decide what new information to keep and what to toss. That could be one reason our dreams are laden with strange plots and characters, a result of the brain’s trying to find connections between what it’s recently learned and what is stored in our long-term memory. Rapid eye movement sleep — so named because researchers who discovered this sleep stage were astonished to see the fluttering eyelids of sleeping subjects — is the only phase of sleep during which the brain is as active as it is when we are fully conscious, and seems to offer our brains the best chance to come up with new ideas and hone recently acquired skills. When we awaken, our minds are often better able to make connections that were hidden in the jumble of information.

哈佛大學醫學院的精神病學教授羅伯特·斯蒂克戈爾德(Robert Stickgold)認爲，睡眠——包括產生了深度睡眠的小睡——會讓我們的大腦得到一個機會去決定新的信息孰去孰留。正因爲此，我們的夢才充斥着奇怪的情節與人物，這是因爲我們的大腦此時正在試圖尋找最近學到的新東西與存儲在長期記憶中的知識之間存在的關聯。快速眼動睡眠——之所以叫這個名字，是因爲發現了這個睡眠階段的研究者很驚異地看到睡覺的人眼皮在急速顫動——是整個睡眠中唯一一個大腦跟完全清醒時同樣保持活動的階段，而且這種睡眠階段看來能爲大腦提供一個孕育新想法，磨鍊近期學會的技能的良機。等到醒來時，我們往往更有能力在錯綜複雜的信息中發現隱祕的聯繫。

Gradual acceptance of the notion that sequential sleep hours are not essential for high-level job performance has led to increased workplace tolerance for napping and other alternate daily schedules.

連睡幾個小時並不是高水平工作表現的必要條件，在漸漸接受了這個概念後，企業也越來越能包容員工在工作場所打盹，或採取其他類似的間斷工作節奏。