Teenagers' sleep patterns may be a clue to their risk of depression. iStockphoto hide caption

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Solid friendships can help buffer life's stress. iStockphoto hide caption

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It may not be the best strategy to stay up late and cram. A new study finds that when teens don't get the sleep they need, all kinds of things can go poorly. iStockphoto.com hide caption

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Jealous? If you have trouble sleeping, several new apps and devices promise to help you figure out why. In this photo from January, Huan Huan, a female giant panda, sleeps in a zoo in Beauval, France. Franck Prevel/Getty Images hide caption

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Sleepy police were likelier to fall asleep while driving, a new survey of nearly 5,000 officers in the U.S. and Canada finds. About 40 percent of officers surveyed reported sleep disorders, with various health implications. Sean Locke/iStockphoto hide caption

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Sleep researchers say parents of a new child can be a risk for long-term insomnia. Timothy M. Black/iStockphoto.com hide caption

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