dem electrolytes
they're classed as a sports drink, rather than energy drink
also, the bottles make good bongs
caffeine's energy wears off quick (and it's not really a very productive kind of energy either, it results in more scattered thought processes; it's enjoyable though, I find). and yeah, regular caffeine consumption would be expected to reduce energy levels over time.
i find energy drinks with taurine in them to produce a more spaced-out effect. not quite lethargic, but more "deer stuck in headlights". (for me, anyway)
caffeine generally makes it hard for me to get to sleep. apart from the caffeine fix in the morning, i wouldn't really say it makes me "more awake" though. gives me a lot of "nervous energy" though, if that can be counted at all as being "more awake".