If you're nocturnal, you get it. You know you have to get up early tomorrow, so you wind down, turn off the screens and prepare for a responsibly early bedtime...only to get a second wind and stay up all night for no good reason. If you've ever wondered why you're cursed to a life of late nights, horribly early mornings, and nonstop coffee, there's a good reason—it all comes down to genetics.