Coffee doesn't seem to really help me aside from keeping me from falling asleep for a short time (~40-60 minutes maybe). I used it most heavily (2-4 small or medium cups a week) when I was suffering from undiagnosed sleep apnea, but even now I occasionally have some when I feel I must be extra sure not to get sleepy, and it doesn't really seem to help me focus and wears off quickly. Does coffee not work on certain people or is there some factor I'm not aware of?