Three words: Reading, Homework, and Settling down. Children do not get enough hours of sleep. Even a teenage child needs as much sleep as a toddler. We've always put our elementary age children to bed at 7pm and we start moving our teens toward bed at 8pm with lights out an hour or so later. This is because it takes them a while to settle down. They will putter around, and ask for drinks, and remember they forgot their homework every night. When they are put to bed early, they will have a chance to settle down, read a little (very important), finish up homework in their beds and then fall asleep much earlier than if they started later. It really works! And it makes for happier children in the morning.