Even if coffee's net effect is zero -- you're as stimulated with it as you are without it -- it can still be positive. Think of it as a way to dial up your adre

Even if coffee's net effect is zero -- you're as stimulated with it as you are without it -- it can still be positive. Think of it as a way to dial up your adrenaline; instead of being excited at random times, or by external events, you're excited when you need to work, and calm when you want to relax.