Ever wonder who those people are, streaming out of the gym at 6 a.m., all finished with that early-bird Spin class and raring to tackle the day? They're mutants—at least according to a recent article in Science. A variation of the DEC2 gene—known as the insomnia gene—allows some humans to feel refreshed and energetic after just six hours of sleep. Mice with the mutant gene spend an hour-and-a-half longer each day on the running wheel compared to their counterparts. Humans born with the gene just make the rest of us feel bad.