If you're getting less than five hours of sleep a night, then you might be a "short sleeper." That's the word from Dr. Daniel Buysse, former president of the American Academy of Sleep Medicine. He says new research has confirmed the existence of "short sleepers" - which is the official name for people who can survive on very little sleep, without needing naps or caffeine. Historically, busy people like Thomas Jefferson and Leonardo da Vinci were thought to be "short sleepers." So is actor James Franco today. Studies have shown that these are people who tend to have faster metabolisms, so they're naturally thinner than the average person. They also have a higher tolerance for pain, and their personality tends to be more outgoing, optimistic, and ambitious. Unfortunately, Dr. Buysse says for every 50 people who same sleep schedule no matter what day it is.