譯文why-we-sleep-a-biological-perspective

1、1Reading 3 Why We Sleep: A Biological Perspective 從生物學(xué)角度考察人類為什么要睡眠By Jerome M. SiegelSection 1 1 Birds do it, bees do it, and even fruit flies appear to do it. Humans certainly do it. The subject is not love, but sleep.

2、 Shakespeare's Macbeth said it “knits up the raveled sleeve of care” and was the “balm of hurt minds, great nature's second course, chief nourisher in life's feast.“ Cervantes's Sancho Panza sang its prai

3、ses as “the food that cures all hunger, the water that quenches all thirst, the fire that warms the cold, the cold that cools the heart... the balancing weight that levels the shepherd with the king, and the simple with

4、the wise. “ 鳥兒/蜜蜂兒/甚至是蒼蠅兒都需要睡覺,人類當(dāng)然也需要睡覺.本主題所談?wù)摰姆菒矍?而是睡眠.莎士比亞說,那是”織補(bǔ)關(guān)照的袖口”和那是”心靈慰藉,自然的賦予,生命的滋養(yǎng)”科文特斯.伯查卻贊歌”食足肚餓,水慰口渴,火曖冬寒,寒靜熱血......這均衡的賜予撫平了牧人與國王的差別,撫平了愚者與智者的差別.”2 The simple and the wise have long contemplated two rela

5、ted questions: What is sleep, and why do we need it? An obvious answer to the latter is that adequate sleep is necessary to stay alert and awake. That response, however, dodges the issue and is the equivalent of saying t

6、hat you eat to keep from being hungry or breathe to ward off feelings of suffocation. The real function of eating is to supply nutrients, and the function of breathing is to take in oxygen and expel carbon dioxide. But w

7、e have no comparably straightforward explanation for sleep. That said, sleep research --- less than a century old as a focused field of scientific inquiry --- has generated enough insight for investigators to at least ma

8、ke reasonable proposals about the function of the somnolent state that consumes one third of our lives. 人們長期關(guān)注著兩個(gè)相關(guān)的問題:什么是睡眠,為什么要睡眠?一個(gè)最新的答案是:睡眠是為了保持警覺和清醒的需要.然后,這個(gè)答案回避了問題本身,如同說吃飯是為了充饑,呼吸是為了免除窒息一樣.其實(shí),吃飯的作用是提供營養(yǎng),呼吸的作用是吸入氧氣和

9、呼出二氧化碳.但我們沒有同樣地直接回答睡眠是為了什么.也就是說, 人們對(duì)睡眠的研究,在不到一個(gè)世紀(jì)以來將之作為一個(gè)重要的研究領(lǐng)域已經(jīng)進(jìn)行了充分的探究,至少對(duì)于這一占去人生三分之一的睡眠的功能提出了合理的解釋.Section 2 What is sleep?3 Despite the difficulty in strictly defining sleep, an observer can usually tell when a su

10、bject is sleeping: the sleeper ordinarily exhibits relative inattention to the environment and is usually immobile. (Dolphins and other marine mammals swim while sleeping, however, and some birds may sleep through long m

11、igrations.) 盡管嚴(yán)格定義睡眠是困難的.但是觀測者一般能看出什么時(shí)候是進(jìn)入睡眠狀態(tài):睡眠者通常對(duì)環(huán)境失去注意,以及靜止不動(dòng).4 In 1953 sleep research pioneer Nathaniel Kleitman and his student Eugene Aserinsky of the University of Chicago decisively overthrew the commonly held

12、 belief that sleep was simply a cessation of most brain activity. They discovered that sleep was marked by periods of rapid eye movement, commonly now known as REM sleep. And its existence implied that something active o

13、ccurred during sleep. All terrestrial mammals have been examined exhibit REM sleep, which 3躍.這些細(xì)胞好像行使管理包括睡眠在內(nèi)的職責(zé),它們被稱為睡眠性神經(jīng)細(xì)胞.激發(fā)睡眠性神經(jīng)細(xì)胞的精確信號(hào)目前仍然不完全了解,但是當(dāng)個(gè)體清醒/體溫升高時(shí)部分這些睡眠性神經(jīng)細(xì)胞是明顯地被激活,這種現(xiàn)象可以用來解釋熱水澡或夏日海濱浴后的睡意.8 On the oth

14、er hand, brain activity during REM sleep resembles that during waking. Brain waves remain at low voltage, because neurons are behaving individually. And most brain cells in both the forebrain and brain stem regions are q

15、uite active, signaling other nerve cells at rates as high as --- or higher than --- rates seen in the waking state. The brain's overall consumption of energy during REM sleep is also as high as while awake. The great

16、est neuronal activity accompanies the familiar twitches and eye motion that give REM sleep its name. Specialized cells located in the brain stem, called REM sleep on cells, become especially active during REM sleep and,

17、in fact appear to be responsible for generating this state. 另一方面,快速動(dòng)眼期的腦活動(dòng)與清醒時(shí)的腦活動(dòng)相似.腦電波仍然處于低電壓狀態(tài),腦細(xì)胞仍然在各司其職.同時(shí),腦前區(qū)和腦干區(qū)大部分細(xì)胞仍然十分活躍, 發(fā)出信號(hào)給其它神經(jīng)細(xì)胞在比率上等于或高于清醒狀態(tài).在快速動(dòng)眼期整個(gè)大腦的能量消耗也與清醒狀態(tài)一樣.在這個(gè)被稱為快速動(dòng)眼期的時(shí)段里,熟悉的抽搐和眼動(dòng)伴隨著最強(qiáng)烈的神經(jīng)活動(dòng)發(fā)生.9

18、 Our most vivid dreams occur during REM sleep, and dreaming is accompanied by fr equent activation of the brain's motor systems, which otherwise operate only during waking movement. Fortunately, most movement during

19、 REM sleep is inhibited by two complementary biochemical actions involving neurotransmitters, the chemicals that physically carry signals from one neuron to another at the synapse (the contact point between two neurons).

20、 The brain stops releasing neurotransmitters that would otherwise activate motoneurons, and it dispatches other neurotransmitters that actively shut down those motoneurons. These mechanisms, however, do not affect the mo

21、toneurons that control the muscles that move the eyes, allowing the rapid eye movements that give the REM sleep stage its name. 我們的夢(mèng)境出現(xiàn)在快速動(dòng)眼期, 夢(mèng)境是隨著大腦動(dòng)力系統(tǒng)的頻繁激活而產(chǎn)生的,大腦動(dòng)力系統(tǒng)除在快速動(dòng)眼期運(yùn)轉(zhuǎn)外,僅見于清醒狀態(tài).幸運(yùn)的是,在快速動(dòng)眼期很多運(yùn)動(dòng)都被兩種互補(bǔ)的生化活動(dòng)抑制住,

22、這生化活動(dòng)涉及神經(jīng)傳導(dǎo)物質(zhì),也就是一種在物理上能將信息在神經(jīng)突觸(就是聯(lián)系兩個(gè)神經(jīng)細(xì)胞之間的節(jié)點(diǎn))之間進(jìn)行運(yùn)載的化學(xué)物質(zhì).大腦停止釋放神經(jīng)傳導(dǎo)物質(zhì),否則將激活運(yùn)動(dòng)神經(jīng)元,和分配其它的神經(jīng)傳導(dǎo)物質(zhì)及時(shí)地阻斷那些運(yùn)動(dòng)神經(jīng)元.然而,這種機(jī)制并不影響控制眼動(dòng)的運(yùn)動(dòng)神經(jīng)元的活動(dòng).10 REM sleep also profoundly affects brain systems that control the body's inter

23、nal organs. For example, heart rate and breathing become irregular during REM sleep, just as they are during active waking. Also, body temperature becomes less finely regulated and drifts, like that of a reptile, toward

24、the environmental temperature. 快速動(dòng)眼期也對(duì)大腦系統(tǒng)控制人體內(nèi)臟器官產(chǎn)生深刻的影響.例如,在快速動(dòng)眼期心率和呼吸如清醒時(shí)一樣,變得不規(guī)律.體溫也變得漂忽不穩(wěn)定,像爬行動(dòng)物一樣趨向于環(huán)境的溫度.11 This brief description of sleep at the neuronal levels is both accurate and as unsatisfying as being awa

25、kened before the completion of a good night's slumber. The tantalizing question persists: What is sleep for? 以上從神經(jīng)元的水平對(duì)睡眠所進(jìn)行的簡述是精確的,但卻是無法令人滿意的,不滿意之處在于,它如同沒有完全睡夠就被叫醒的那種感覺.那個(gè)撩人的問題還在: 為什么要睡眠?Section 3The Function of Sle