It's a nightly habit for some of us. You're lying in bed, totally exhausted, and for some reason can't catch a wink. Or perhaps you fall asleep, then wake up a couple of hours later to an endless cycle of tossing and turning that culminates in a 4:00 a.m. Instagram-stalking session. Could you have prevented the restlessness with a simple fix? Yes, and here's a hint: It has to do with what you ate for dinner.