Ah, so decaf doesn't actually have no caffeine in it. Intriguing.
(PeterTaylor) Decaf also has most of the pulse-raising etc effects of coffee normally associated with caffeine. How much this is due to the presence of caffeine and how much to psychosomatic effects, I don't know.
And also due to caffeiene not being the only part of coffee that... no! Stop! I'm sorry! It wasn't heresy! This guy just paid me to come here and... noooooo!