As a recovered Mountain Dew head, I agree. The sugar in Mountain Dew is the worst of it. I used to require five or so Mountain Dews every day. When I slowly stopped drinking it (I switched completely to coffee to avoid caffeine withdraw) I stopped getting really hyper then crashing five times a day. My concentration is much better without Mountain Dew. It took me about five weeks to switch (one less can per week).

Not too long afterward I got my caffeine intake down to whatever is in two to four cups (or shots of espresso) of coffee a day, where it's been ever since.

Now, a few years later, I'm in the process of limiting myself to two cups (or shots of espresso) a day. I'm down to three, but it's fairly difficult to go lower -- which sucks.

Don't drink all this shit! Drink water and sleep when you're tired; maybe have a cup of coffee a day. Your concentration will be much better. There's natural variance in energy levels throughout the day. Stimulants just make the highs higher and the low lower -- but they also make the highs shorter and the lows longer. Check up and really pay attention to yourself through the day -- you'll likely want to reclaim your energy back from all these supposed "energy drinks" and other garbage.