Water definitely helps, but some people have become chemically dependent on caffeine or other outside stuff to stay awake, and it's difficult to kick the habit.
If I drink an energy drink, I prefer Full Throttle. I used to drink 2 a day at CC, and if I did it on an empty stomach I would have a hard time forming logical sentences. Since I'm not a woman, that wasn't working for me so I had to gradually wean myself off of them. It took a few months, but I'm to the point that unless I'm just loopy tired, I won't touch them. I would say I have about 1 per month if that.
I drank 2 of the 24 oz rockstars a few years back when I did a late night marathon drive from Canada to SLC. I probably had them in a 6 hour period, and as we were coming accross idaho at sunup I was freaking. I would twitch like I was falling asleep, but I wasn't falling asleep. I'm also 70% certain that my heart was skipping every other beat. Don't ask me how that is possible, but I swear I had like a 20 bpm heart rate lol.
Cody