While watching this Ted Talk – Jeff Iliff: One more reason to get a good night’s sleep | TED.com.
I made a quick infographic:
For those that are interested in reducing sleep, I also think using polyphasic sleep, or scheduled naps to extend your day fascinating… though it helps to go off caffeine if you want to really do that routine (so you don’t miss you power naps) and man, I just love coffee too much to do that. 🙂
View more claimed sleep patterns on wikipedia