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Napping: 90 minutes of zzzz's hits the reset button on memory

February 23, 2010 |  8:19 pm

Nap Leonardo da Vinci took them, as did Napoleon Bonaparte, Johannes Brahms and Winston Churchill. I'll bet you could use one right now.

Midday naps have long been touted as a good thing, lowering blood pressure and driving down your risk of heart attack. If you snooze long enough, researchers have found they also permit your memory banks to do their filing, leaving your brain cleared and ready to learn in the latter half of the day.

UC Berkeley psychology professor Matthew Walker and colleagues put 39 young adults through a demanding learning task  and tested on it at noon. At 2 p.m., they divided the students into two groups and invited half of them to take a siesta for 90 minutes, while asking the remainder to stay awake. At 6 p.m., both groups were returned to the day's learning task and tested again.

The siesta group went into the 6 p.m. task readier to learn, and performed 10% better on the test than they had earlier. The no-nap group's performance declined by 10%, Walker reported. While not all the nappers slept for the same length of time, those who had more stage-2 non-REM sleep, a lighter form of sleep in which one does not dream, had the greatest performance enhancement.

The group presented its findings at the annual meeting of the American Association for the Advancement of Science in San Diego this week, where I'll bet a lot of the nation's scientists are making good use of the findings after lunch in darkened meeting rooms.

You'd be amazed at how many people are devoted to the napping lifestyle. Check out this book, or blog, for instance.

-- Melissa Healy

Photo: Leiana Takeda, left, and her sister Kanaha of San Diego, take a nap. Credit: Christina House / For The Times