Go off coffee for a few days and ask yourself if it's a drug or not. And if it's a drug. Are you addicted? Might there by chemicals in it that alter your mood, etc. As you kow Scott, I stopped drinking coffee a few years ago--but started drinking it again--but remain at 80% of my previous consumption. I'm 61. I don't believe I can tolerate it like I used to. I believe it makes me "rushy" in my writing and gives me tunnel vision. Not arguing you should quit. This is just a don't kid yourself message that it really IS serious business, the coffee stuff.
Again, first question, are you addicted? If so, who is writing, the coffee or you?