The Science of Slumber

Special issue on sleep

The science of slumber | Photo: Tommy Leonardi

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Despite its utter mundanity, sleep resists simple scientific explanation. It appears to recuperate the body and refresh the mind, but exactly how isn’t at all clear. The brain appears to be as active in some of the throes of somnolence as it is in sustaining wakefulness.

By inquiring into all that happens in the brain and body during sleep, researchers aim to paint a more complete picture of why people sleep — and why sleep sometimes goes awry, as Science News staff writers Tina Hesman Saey and Laura Sanders report in this special section.

Scientists seeking the reasons for sleep hope to discover some evolutionary insight: Mammals sleep presumably because it offers some survival advantage. But recent work suggests that explaining sleep as an adaptation for saving energy doesn’t add up. Scientists are skeptical that saving energy is the only (or even the main) reason that sleep has evolved, as described in the article “The why of sleep.”

Extreme fatigue is the closest humans ever come to sleep while still aware enough to ponder its mysteries. At those times, sleep pulls hard, like a current sweeping up a tired mind, carrying consciousness away. How the brain controls this transition between wake and sleep lies at the heart of disorders such as insomnia and narcolepsy, as discussed in “Sleep gone awry.” The third article, “Dying to sleep,” documents what happens when people go without enough sleep. Chronic sleep deprivation poses more serious health risks than many had thought, research shows.

In sleep, the very tool humans use to explore and analyze the world seems to go blank — or, in some dreamy interludes, apparently haywire. No wonder then that scientists, and especially those who study the brain, urgently want to fill in that blank and explain the still largely veiled experience into which most fall thankfully every night. — Eva Emerson


Darwin’s Evolution, by Tom Siegfried
The why of sleep
By Tina Hesman Saey

Brain studies may reveal the purpose of a behavior both basic and mystifying.

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Evolution’s Evolution, by Rachel Ehrenberg
Sleep gone awry
By Laura Sanders

Researchers inch closer to causes, cures for insomnia, narcolepsy.

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Molecular Evolution, by Tina Hesman Saey
Dying to sleep
By Tina Hesman Saey

Getting too little sleep can impair body and brain, and could even be deadly.

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Molecular Evolution, by Tina Hesman Saey
All kinds of tired
By Susan Milius

SIDEBAR: Studying animal sleep offers the prospect of discerning evolutionary patterns in sleep pointing to some ancient function.

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