nap

nanonap (10-20 secs): sleep studies haven't yet concluded whether there are benefits to these brief intervals, like when you nod off on someone's shoulder on the train.
micronap (2-5 mins): shown to be surprisingly effective at shedding sleepiness.
minimap (5-20 mins): increases alertness, stamina, motor learning, and motor performance.
original powernap (20 mins): includes the benefits of the micro and mini, but also improves muscle memory and clears the brain of useless built-up information, which helps with long-term memory (remembering facts, events, names).
lazyman nap (50-90 mins): includes slow-wave plus rem sleep; good for improving perceptual processing; also when the system is flooded with human growth hormone, great for repairing bones and muscles.