Why Do We Sleep? The Ultimate Question

第一章：为什么我们要睡觉？那个终极问题

Chapter 1: Why Do We Sleep? The Ultimate Question

Every night, without exception, you surrender to it. You close your eyes, your breathing slows, and your consciousness fades into a strange, intangible realm—a place where time moves differently, where the laws of your waking world seem to dissolve, and where you may fly, fall, run from something, or stand perfectly still in the middle of a crowd of strangers. When you wake, you often cannot quite remember the details. The experience feels unreal, almost nonsensical. Yet it is one of the most fundamental aspects of being alive.

每一个夜晚，毫无例外地，你会向它臣服。你闭上眼睛，呼吸放缓，意识消融在一片奇异而难以捉摸的疆域——在那里，时间以不同的方式流动，你清醒世界的法则似乎消散殆尽，你可能会飞翔、坠落、逃跑，或是静静地站在一群陌生人中间。醒来后，你往往记不清那些细节。这种体验感觉不真实，近乎荒谬。然而，这是活着最基本的现象之一。

You will spend approximately one-third of your entire life in this state. If you live to seventy-five, that is roughly twenty-five years—an entire lifetime of consciousness simply... gone. Vanished into something we call sleep.

你将用大约三分之一的人生处于这种状态。如果你能活到七十五岁，那大约是二十五年——整整一辈子的意识，就这么...消失了。消失在一种我们称之为睡眠的状态里。

For most of human history, this daily disappearance was deeply puzzling. Ancient civilizations had explanations, of course—the Greeks believed sleep was a time when the soul left the body, traveling to mysterious realms; the Egyptians thought the god of death, Osiris, presided over the night; many cultures saw dreams as prophecy or divine communication. These interpretations tell us something important: our ancestors recognized that sleep was *significant*, even if they couldn't explain why.

在人类历史的大部分时期，这种日常的"消失"一直令人困惑。当然，古代文明有其解释——希腊人认为睡眠是灵魂离开身体、游历神秘领域的时刻；埃及人认为死亡之神奥西里斯主宰着夜晚；许多文化将梦境视为预言或神圣的交流。这些解释告诉我们一个重要的事实：我们的祖先认识到睡眠是*重要的*，即使他们无法解释其中的原因。

But here is what is truly remarkable, and what makes sleep one of the most fascinating puzzles in all of biology: sleep is not unique to humans. Every animal that has ever been studied—every mammal, every bird, every reptile, every fish, every insect that has been carefully examined—demonstrates some form of rest or sleep-like state. This is not a minor feature that some animals developed and others didn't. It is *universal*. From the mighty blue whale cruising the ocean depths to the tiny fruit fly buzzing around overripe bananas, sleep is there.

但真正令人惊叹的是——这使得睡眠成为生物学中最迷人的谜题之一：睡眠并非人类独有。 每一种被研究过的动物——每一种哺乳动物、每一种鸟类、每一种爬行动物、每一种鱼类、每一种被仔细观察的昆虫——都展现出某种形式的休息或类睡眠状态。这不是某些动物进化出而另一些没有的小特征。它是*普遍的*。从巡游深海域的庞大蓝鲸，到绕着熟透香蕉嗡嗡飞舞的小果蝇，睡眠无处不在。

Why? Why would evolution, that relentless optimizer of energy and efficiency, conserve such a seemingly "wasteful" behavior? In sleep, you cannot eat, cannot mate, cannot care for offspring, cannot search for food or avoid predators. You are utterly defenseless and non-productive. From a purely survival standpoint, sleep appears to be an extraordinary liability.

为什么？为何那个不断优化能量与效率的进化过程，会保留这样一种看似"浪费"的行为？在睡眠中，你无法进食、无法交配、无法照顾后代、无法觅食或躲避捕食者。你完全毫无防备，毫无生产力。仅从纯粹的生存角度来看，睡眠似乎是一种极大的负担。

This is the question that haunts sleep scientists, the question we will explore throughout this book: Why do we sleep?

这就是困扰睡眠科学家的问题，也是我们将在本书中不断探索的问题：为什么我们要睡觉？

And as we will discover, the answer is far more profound—and far more consequential for your daily life—than anyone ever imagined.

我们将发现，这个问题的答案比任何人曾经想象的都要深刻——而且对于你的日常生活来说，后果也要重大得多。

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从亚里士多德的困惑到达尔文的梦魇

From Aristotle's Puzzles to Darwin's Nightmares

The scientific study of sleep has a surprisingly long history, though for most of it, progress was agonizingly slow. Our journey begins in ancient Greece, with perhaps the greatest thinker of the classical world.

睡眠的科学研究有着出人意料的漫长历史，尽管在大部分时间里，进展都极其缓慢。我们的旅程从古希腊开始，从古典世界或许最伟大的思想家开始。

Aristotle (384-322 BCE) was the first person on record to offer something resembling a scientific explanation for sleep. In his treatise *On Sleep and Sleeplessness*, he proposed that sleep occurred when the body accumulated "warm vapors" from digestion, which then rose to the brain and caused the body to become heavy and inactive. While this sounds charmingly naive to modern ears—it wasn't until the seventeenth century that William Harvey correctly described blood circulation—Aristotle's approach was revolutionary. He was trying to find *mechanistic* explanations for natural phenomena rather than attributing them to the gods.

亚里士多德（公元前384-322年）是历史上第一个为睡眠提供类似科学解释的人。在他的论文《论睡眠与失眠》中，他提出睡眠发生在身体积累消化产生的"温暖蒸汽"时，这些蒸汽随后上升至大脑，导致身体变得沉重和不活跃。虽然这在我们现代人听来天真可爱——直到十七世纪，威廉·哈维才正确描述了血液循环——但亚里士多德的方法是革命性的。他在寻找自然现象的*机械论*解释，而不是将其归因于神灵。

For nearly two thousand years after Aristotle, sleep research essentially stagnated. Oh, there were observations, theories, and endless speculation. The Roman physician Galen proposed that sleep was caused by a lack of "nervous force" flowing to the brain. Medieval thinkers debated whether dreams came from God or the devil. But no one developed systematic methods to study sleep, no one performed experiments, no one challenged the fundamental assumptions about what sleep actually was.

在亚里士多德之后的近两千年里，睡眠研究基本停滞不前。哦，有观察、有理论、有无尽的猜测。罗马医生盖伦提出，睡眠是由流向大脑的"神经力量"不足引起的。中世纪的思想家争论梦境是来自上帝还是魔鬼。但没有人发展出系统性方法来研究睡眠，没有人进行实验，没有人挑战关于睡眠实际上是什么的基本假设。

The breakthrough came in the early nineteenth century, and it came from an unexpected source: electricity. In 1815, the Italian physiologist Luigi Galvani demonstrated that electrical stimulation could cause a dead frog's leg to twitch. This discovery, and the subsequent work of others, revealed that nerve impulses were electrical in nature. Suddenly, scientists had a new way to think about the brain and, by extension, about sleep.

突破发生在十九世纪初，来源出人意料：电。1815年，意大利生理学家路易吉·伽伐尼证明电刺激可以使一只死青蛙的腿抽动。这一发现以及随后其他人的工作表明，神经冲动本质上是电的。突然间，科学家们有了一种思考大脑——进而思考睡眠——的新方式。

But the true revolution in sleep science came in 1953, and it was triggered by what initially seemed like an accidental discovery. Eugene Aserinsky, a graduate student at the University of Chicago, was monitoring sleeping infants when he noticed something strange: periodically during sleep, the subjects' eyes would move rapidly beneath their closed eyelids. This wasn't the slow, rolling movement seen during normal sleep. This was fast, jerky, almost purposeful movement. When Aserinsky woke his subjects during these periods, they almost always reported vivid dreams.

但睡眠科学的真正革命发生在1953年，最初看似一个意外发现触发了它。尤金·阿塞林斯基，芝加哥大学的一名研究生，正在监测睡眠中的婴儿，这时他注意到了一些奇怪的现象：在睡眠期间，受试者的眼睛会在闭着的眼睑下快速移动。这不是正常睡眠中看到的缓慢、滚动式移动。这是快速的、痉挛的、几乎是目标明确的移动。当阿塞林斯基在这些时期唤醒受试者时，他们几乎总是报告生动的梦境。

Aserinsky showed this to his advisor, Nathaniel Kleitman, who was one of the pioneers of modern sleep research. Together, they confirmed the finding and named it REM sleep—Rapid Eye Movement sleep. This discovery was, in retrospect, one of the most important in all of sleep science, because it revealed that sleep was not a uniform, simple state. There were *stages* of sleep, each with distinct characteristics. Sleep was a dynamic, complex process, not merely the absence of wakefulness.

阿塞林斯基将这一发现展示给他的导师纳撒尼尔·克莱特曼，他是现代睡眠研究的先驱之一。他们一起证实了这一发现，并将其命名为REM睡眠——快速眼动睡眠。回想起来，这一发现是所有睡眠科学中最重要的发现之一，因为它揭示了睡眠不是一个统一的、简单的状态。睡眠有*阶段*，每个阶段都有独特的特征。睡眠是一个动态的、复杂的过程，不仅仅是清醒的缺失。

Within a few years, Kleitman and others had mapped out the basic architecture of sleep—the cycling between REM and non-REM stages, the progression through different depths of sleep, the typical patterns across a night. But they still couldn't fully answer the fundamental question: *why*?

在短短几年内，克莱特曼和其他人已经绘制出睡眠的基本架构——REM与非REM之间的循环、不同睡眠深度的进程、一夜中的典型模式。但他们仍然无法完全回答根本问题：*为什么*？

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睡眠的普遍性：自然界的共识

The Universality of Sleep: Nature's Consensus

To understand why sleep matters, consider first just how *pervasive* it is. Sleep is not an oddity found in a few species. It is the norm across the entire animal kingdom.

要理解睡眠为何重要，首先考虑它有多*普遍*。睡眠不是在少数物种中发现的怪异现象。它是整个动物界的常态。

哺乳动物：与我们同眠

Mammals: We Sleep As They Sleep

Every mammal studied to date sleeps. The patterns vary—lions sleep up to twenty hours a day (though in short bursts th