Now you mention it, I have been known to drink a cup of fully caffeinated tea without major ill effects, but half a cup of fully caff coffee gave me a near-panic-attack last year. So it could perfectly well be the other stuff in coffee, yes.

I slept a bit, but not really enough. This morning I was incompetent enough that I almost fell over while opening a door at work. (It's quite a heavy door; usually I grab the handle and lean back. I missed the grab but leaned back anyway.) I suspect I'm not going to get much believable work done today...

So, tell us about the unbelievable work you'll be doing, then.