There is an article in the Wall Street Journal about people who need less than six hours of sleep per night - a.k.a short sleepers. Short sleepers are less common than most people think. In fact, the article quotes a famous sleep psychiatrist, Dan Buysse, who says that there only 5-6 true short sleepers for every 100 people that make such claims. People who tolerate six hours or less of sleep per night for the work week are not what we call short sleepers. If you can sleep longer on the weekend, than you are not a short sleeper. You are sleep-depriving yourself during the work week and catching up on lost sleep on the weekends. Short sleepers sleep < 6 hours seven days a week.
We don't know why some people are short sleepers. It can start in childhood and can run in families. There is no way a person can teach themselves to be a short sleeper either.
Short sleepers tend to be more energetic, outgoing, optimistic, and ambitious. Their metabolism tends to be higher than regular sleepers. The article in the WSJ thought this was confusing, since sleep deprivation is linked to obesity. However, it could be argued that true short sleepers are not sleep-deprived. Finally, short sleepers tend to have higher tolerance for physical pain and psychological setbacks.
Currently, researchers are attempting to find out the genetics behind short sleepers. This could have applicability in our fast-paced modern lifestyle. In the mean time, get some sleep...enough sleep.