How does caffeine effect you?

most of the time I drink decafe, but regular does not seem to bother me.

I'm 2 weeks out and it's done a doosey on me. I had 1 cup of coffee last Thursday and I was awake for almost 24 hrs. Before surgery I always drank 1 cup a day early in the morning with no side effects. I have no idea why that happend but I'm almost scared to drink coffee again.