Scientific napping!

Dr. Sara Mednick earned her PhD at Harvard by studying how to take a nap. She's written a book about it called, "Take A Nap! Change Your Life." She also designed this nap wheel to improve the experience. Using it, the best time for one's own napping is found by setting the pointer to the time one awoke from a night's sleep, going to the intersection of the variously colored eccentric circles and arranging one's nap to include that point.

She goes into much more detail on her website, http://www.saramednick.com/ and this downloadable, interactive nap wheel can also be found there.