So, apparently I have Crohn's Disease. I found that out because the Red Bull irritated my digestive system so much that I had my first flare up and ended up in the hospital – twice. That was three years ago, and I'm only just now starting to recover from it. I'm getting my energy back, I can drink and eat more food, etc. Except I have to take immunosuppressant medication to keep the Crohn's controlled, which means I get sick (cold, flu, etc.) extremely easily, and I stay sick a lot longer. Also, I've had a ton of radiation exposure due to all the CAT scans, etc. I've gone through.
So, next time someone tells you Red Bull (or whatever) is bad for you, don't just shrug it off like I did. Our bodies are fragile machines in a delicate balance. Upset that balance enough and the machine goes haywire, and it's pretty hard to find spare parts.
I was a jittery mess for the two months I had a 3+/day habit.
I did find this:
http://www.springerlink.com/index/1185172kt700868t.pdf
Which has as a lead "Energy drink consumption has been anecdotally linked to the development of adverse cardiovascular effects in consumers, although clinical trials to support this link are lacking.", but there are some interesting observations in it.
And this one:
http://www.modern-psychiatry.com/taurine.htm
and this one:
http://women.timesonline.co.uk/tol/life_and_style/women/diet...
Of the not-so-sane sources this one seemed a bit more balanced than most:
http://brianx.com/nightlife/energy-drinks.html
What the hell is 'taurine' ? http://en.wikipedia.org/wiki/Taurine
Enjoy the read.
I stayed up all night before my sub-thesis due date finishing it off thanks to Red Eye (red bull analogue). I had so much of it that I was literally shaking late into the night.
In general my caffiene intake is zero - my theory is if you drink it every day it has less of an effect than when you really need it. I rely on willpower most of the time if working late.
I haven't looked at evidence in years, but the gastrointestinal and heart rate effects of even higher levels can be remarkable. I remember medical journal articles (Am J Psychiatry, i believe) referring to it as "caffeinism" - since the mental-alertness benefits habituate, but not the autonomic stimulation.
Like with any mind-alteration: exercise caution. Listen to what your own body tells you.