The 10, 3, 2, 1, 0 rule is like a countdown for a great night's sleep. It goes like this: 10 hours before bed, no more caffeine. Three hours before bed, avoid big meals and workouts. Two hours before, stop working. One hour before, no more screen time. And 0 is the number of times you hit the snooze button. Follow this, and you're on your way to dreamland.