Sara Mednick

That’s because so-called power naps lasting less than 30 minutes allow the brain to rest in a way that makes you more alert, experts say. The naps are not so long that you slip into deeper sleep that would leave you groggy after waking up. ... Shorter naps only include stage-two sleep, which is particularly helpful for alertness and memory, said Sara Mednick, a sleep researcher at University of California-Irvine.

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