Your Brain: The Missing Manual

Chapter 3. Sleep: Taking Your Brain Offline

Sleep is one of the quirkiest brain behaviors. If it wasn't such a fundamental part of your life, you'd find the whole idea more than a bit outlandish. Think about it: For nearly a third of the day, your brain paralyzes your body. It then slips into a state of supposed rest that has bursts of electrical activity as energetic as when you're awake. And to top things off, the sleeping brain reels with hallucinations that rival those induced by the most potent controlled substances.

Scientists who study sleeping brains have unearthed all kinds of fascinating things. But they still can't agree on why we do it. In fact, they still can't completely agree that we actually need to do it. And the story gets even stranger when neuroscience shifts its attention to the surreal world of dreams.

In this chapter, you'll take a long, sober look at the sleeping brain. First up: a consideration of possible reasons your brain craves sleep (including a look at why it entertains itself with wild, convoluted flights of fancy while you're out cold). As you size up the science of sleep, you'll also dip into its many practical uses—for example, how sleep bolsters learning, how to harness the creativity of your dreams, and how to get a good nap.

Your Biological Clock

Most humans are well adjusted to the basic schedule of modern life—sleeping through breakfast, dozing off after lunch, and watching late night television when they should be deep asleep. Against this backdrop, ...