Workers try to remove some of the 11 million gallons of oil spilled by the Exxon Valdez off Alaska in 1989. The ship's third mate may have been up for 18 hours before the accident. Rob Stapleton/AP hide caption

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To sleep, perchance to consolidate important connections in far-flung parts of the brain. Alberto Ruggieri/Illustration Works/Getty Images hide caption

itoggle caption Alberto Ruggieri/Illustration Works/Getty Images
Daniel Horowitz for NPR
Katherine Streeter for NPR

Play now, pay later: consistency matters when it comes to kids and sleep. iStockphoto.com hide caption

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Napping in class may be common, but it's also a sign that kids need more sleep. iStockphoto.com hide caption

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U.S. Army Pvt. Freymond Tyler sleeps on a laptop next to his gun at combat outpost Makuan in Kandahar province, Afghanistan, in 2011. Romeo Gacad/AFP/Getty Images hide caption

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Many Americans aren't getting the recommended seven to nine hours per night. Franck Camhi/iStockphoto.com hide caption

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