I limit my caffien intake now, in a "survival situation" I would hazard a guess that artificial stimuli could prove hazardous. If you need to stay awake and you know this is imperative then you will in my experience. There is also the "animal within" to take into account, I used to be able to nap but would wake if someone breathed too deeply in the next room, while on maneuvers.
Obviously you know that caffeine is only a necessity because you are addicted to it. You've forgotten how to sail through the day without a coffee crutch,and that might put you in a very bad position when the SHTF. Do you ever consider weaning yourself off it so that looking for your next caffeine buzz will be one less thing to worry about? I have been addicted to caffeine, not in coffee as I can't stand the stuff, but in sodas, so I do know what you mean about the headaches and the debilitating lethargy if you don't keep it coming. Getting off caffeine was one of the best things I have done for myself, now that it's over I can get through the entire day from before sun-up to late at night without all the ups and downs.
Adolph Hitler also had a drug developed for his troops to keep them awake, as i seem to recall being told once. oh, what was that stuff called, meth something or other...
Any type of active ingredient has different effects on everyone, that's because of body chemistry. What makes one person paranoid and delusional makes another relaxed and content. How about some mustard moss?
