Early afternoon is the best time to catch a few winks, thanks to a natural drowsiness-inducing dip in body temperature (and no, it isn't because of what you ate). Your circadian rhythms are also primed for sleep around this time.
Consider it time well spent — a NASA study found that pilots who napped were twice as alert and improved their performance by 34 percent. You don't have to be preparing for a space mission to benefit; a 20-minute nap can improve your work performance, your mood and help you have a better workout.