On a recent weekday morning, I was struggling to wake my 16-year-old so she wouldn't miss her first class. I had used all of my morning wake-up tricks, from nudging her to flipping on the lights and even summoning our dog to jump on the bed. At long last, my daughter was on her way to school, but not fast enough to avoid another tardy. On other mornings, I let her sleep in because I know she hasn't gotten enough hours of rest.