Caffeine isn’t always a bad thing. In moderate amounts it can boost energy, memory, and athletic performance. It may protect against certain diseases, like type 2 diabetes. But too much can make you anxious and jittery. It can affect your sleep, digestion, blood pressure, and heart rate. Children should be careful, as well. Too much caffeine can damage a child's developing heart, blood vessels, and nervous system. So make sure to keep track of how much you -- and your children -- get.