grr
Caffeine addiction is a curious thing. You feel the headache of withdrawal coming on when you haven't met your body's expected quota for the day, so you hurry up and get yourself a coffee, but alas, it's too late. Nothing can ward off that headache. Not two tylenols, not two cups of coffee. I don't think it would work the same way with, say, a heroin addiction - presumably withdrawal symptoms cease once you feed your addiction; why must caffeine be so stubborn?
I've had an annoying headache most of the day, and I didn't get enough sleep last night. The combination is not a friendly one...