If you drink too much caffeine, such as gulping down a large amount of Coke or Pepsi, you will feel the effects, like having a faster heart rate. You may feel more nervous or edgy. Unable to fall asleep. Less hungry. Sharper eyesight. Less thirsty. These are all things that prepare you for an emergency, like if a tiger was chasing you, but with chemicals such as too much sugar or caffeine. In moderation I think they are okay to help you stay focused and study better, but too much of it can make you sick.
