I'm not sure about the environment you work in but the enterprise office (Bank) I'm in at the moment has a monumental caffeine intake. I've had a problem with energy drinks since high school which has carried on into my later life but this is just me. I find I work best on an if needed basis, I won't just have a coffee or Rockstar or something if I don't need it, just if I feel myself dropping off, usually in the afternoon.