An afternoon nap markedly boosts the brain's learning capacity

"BERKELEY -- If you see a student dozing in the library or a co-worker catching 40 winks in her cubicle, don't roll your eyes. New research from the University of California, Berkeley, shows that an hour's nap can dramatically boost and restore your brain power. Indeed, the findings suggest that a biphasic sleep schedule not only refreshes the mind, but can make you smarter."

http://www.berkeley.edu/news/media/releases/2010/02/22_naps_boost_learning_capacity.shtml