Many years ago I was told that it takes 30 minutes for caffeine to hit your bloodstream, and that the buzz you get instantly from drinking coffee is due to the sugar. Well, when I stopped putting sugar in coffee I still got an instant head-clearing buzz, which required explanation.
Option 1: Caffeine goes straight to your bloodstream, absorbed through your mouth, tongue and throat, and the "30 minutes" story is crap.
Option 2: Something else.
The "something else" I chose was to joke that my body has a learned response to caffeine, and as soon as it detects the telltale signs (taste/sensations of hot coffee) it releases adrenaline ahead of time, adrenaline release being one of the normal effects of caffeine (which makes it great for hayfever, incidentally, as well as for clearing lactic acid from your muscles, provided you balance the diuretic effect with increased water intake).
Other options include the heat prompting an adrenaline release, and a purely psychosomatic response, aka "placebo effect".
Well, well, well. Speaking of the placebo effect, excellent brand-new blog Science Based Medicine has a piece on that very issue, and please for the love of $DEITY, go and read it.
Included is this paragraph:
"Bausell’s thorough discussion of the placebo phenomenon is illuminating and invaluable. He covers the history of research on placebos and tells some fascinating anecdotes. He argues that placebo response is not just imagination. It is a learned phenomenon, a conditioned response. You respond to a placebo pill because you have previous experience of being helped by pills. Morphine injections in dogs cause a side effect of salivation: after a while, you can inject water and they will respond with salivation. Physiologic effects from placebo are always smaller than with the real thing, but apparently they do occur. The evidence for objective physiologic effects may not be entirely convincing, but it is certain that pain and other subjective symptoms respond to placebos. And there is even research suggesting a mechanism: the release of endogenous opioids, pain-relieving chemicals produced by our own brains. If you counteract those chemicals with a narcotic antagonist like Narcan, you can block the placebo response."
So, not a purely psychosomatic effect then. More of a psychophysiological effect. If a placebo response to an expected pain medicine promotes a biochemical response in the body, isn't it reasonable to assume that a placebo response to coffee can promote a biochemical response in the body? Hmmmmm?
(N.B.: I haven't actually researched the absorption rate of caffeine, I really can't be bothered. And although I have consumed decaffeinated coffee before, I haven't done any real comparisons of subjective response between hot caffeinated and hot de-caf. It'd be a cool little home experiment, if anyone's interested.)
P.S.: Oh, alright then. For those who aren't used to *nix command lines like Linux or BSD, "$DEITY" means "your current deity". It actually means "the current local value of DEITY", but let's not pick hairs.