Via Daniel Coyle’s excellent book The Little Book of Talent: 52 Tips for Improving Your Skills:
Napping is common in talent hotbeds, and features both anecdotal and scientific justification.
The anecdotal: Albert Einstein was good at physics, and he was really good at his daily post-lunch twenty-minute snooze. Other famous nappers include Leonardo da Vinci, Napoleon Bonaparte, Winston Churchill, Thomas Edison, Ronald Reagan, John F. Kennedy, and John D. Rockefeller. Spend time with any professional athletic team, and you’ll find that they’re also professional nappers.
The science: Napping is good for the learning brain, because it helps strengthen the connections formed during practice and prepare the brain for the next session. Researchers at the University of California, Berkeley, found that napping for ninety minutes improved memory scores by 10 percent, while skipping a nap made them decline by 10 percent. “You need sleep before learning, to prepare your brain, like a dry sponge, to absorb new information,” said the study’s lead investigator, Dr. Matthew Walker.