“The Pleasures and Pains of Coffee”
blissbat.net
blissbat.net
In my experience after a week or two off caffeine my energy levels actually improve & are more sustainable (although everyone's metabolism is different; reason why we all need to experiment for ourselves).
Did you try changing/hacking your diet and sleep cycles in the same process? I've found sugar problematic if I'm not on caffeine.
EDIT: Ah, should have gone straight to Wolfram Alpha: The answer is that if you lived to be 20 odds were you'd live to 60. Unless, alas, you were Balzac.
http://m.wolframalpha.com/input/?i=life+expectancy+at+20+in+...
Alpha is the amateur demographer's dream. Just look at those tasty charts and graphs. Of course I didn't read closely enough to figure out where this data was coming from. ;)
/sarcasm
Nietzsche's Ecce Homo has similarly interesting musings on the subject of diet and exercise.
I would get a lot of stomach aches, grogginess and coffee burn out from drinking regular drip. Though he is describing some sort of weird tea-like method for drinking coffee, I imagine it's as bad.
Drinking a few espressos does not give me any issues, unless there is an issue with the extraction and I can feel like I've been poisoned. You have to trust your barista.