Get the Popular Science daily newsletter💡 Breakthroughs, discoveries, and DIY tips sent six days a week. Hours before sunrise, society’s earliest larks begin their day. Tales of Apple’s Tim Cook attending to his email at 3:45 a.m., novelist Barbara Kingsolver writing furiously at 4 a.m., and Michelle Obama starting her gym workout at 4:30 a.m. headline the early bird media fanfare. Early risers are the most celebrated in America’s optimization-obsessed culture that has decided the key to success is being up far before the sun. But there’s a lot these “aspirational” narratives leave out, like the fact that pre-dawn wake-ups only work if you’re wired for early rising—they can be downright unhealthy if you’re not.  What is your chronotype? Sleep and wake-up schedules are based on something called chronotype. Your chronotype is your biological inclination to fall asleep and wake up at certain times. And everyone has a different one: there are larks (early to bed, early to rise), doves (in the middle, this is most people), and owls (late to bed, late to rise).  …