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.