For a small group of people—perhaps just 1% to 3% of the population—sleep is a waste of time.

Natural "short sleepers," as they're officially known, are night owls and early birds simultaneously. They typically turn in well after midnight, then get up just a few hours later and barrel through the day without needing to take naps or load up on caffeine.

They are also energetic, outgoing, optimistic and ambitious, according to the few researchers who have studied them. The pattern sometimes starts in childhood and...]]>