It isn't easy to get away from these electronic devices -- and, if you're like most teens, you spend a lot of time with them. The typical teenager logs more than 7 hours a day and more than 50 hours a week glued to a television, computer, or cell phone, research shows. No doubt, screen time can be fun. The problem is that too much of it can take a toll on your health and your grades. Think about these five important facts.