I think that if you're needing an energy drink of some sort to keep you awake through the day, you
may want to reconsider your schedule. An extra hour of sleep makes all the difference!
That being said, Orange juice or even Cranergy (some weird cranberry drink thing, does wonders!)
both work quite well, and are far healthier. Penguin more or less nailed it.
Again, if you really need that three to four hours of "overboost", use it. If you don't, sleep is the better option for sustaining energy.
-Penguin
It's worth noting, however, that one should not "over-overboost". Drinking 2+ energy drinks, or
even one energy drink within a short amount of time have prominent, temporary side-effects.
HIGHLY advisable NOT to drink more than one or two a day. My step-father relied on AMP and
Mountain Dew, he loved to drink them, an AMP or two plus two or three mountain dews for a day of work.
He eventually had a heart-attack during PT due to drinking an AMP and a mountain dew beforehand,
which led to his flight-status being permanently revoked. He was a UH-60 Crewchief/mechanic,
and he loved flying.
The point I wanted to make, don't overdo it. Know your limits, find something that works for you
without crossing the line.