For as long as Seemay Chou can remember, she has gone to bed at midnight and woken around 4:30 a.m. Chou long assumed that meant she was a bad sleeper. Not that she felt bad. In fact, sleeping just four hours a night left her feeling full of energy and with free time to get more done at her job leading a research lab that studies bacteria. “It feels really good for me to sleep four hours,” she says. “When I’m in that rhythm, that’s when I feel my best.”