Was twitchy, sweated a lot, got sick easier, slept worse, and got worse results at the gym. It works great for a day, and then you crash hard, it's also addictive. Spikes blood pressure. Another poster reminded me about the headaches, which I normally NEVER have. I am under the impression that its worse than drugs (dont do drugs, so can't tell). Affects are very, very strong.
Solution is to lift lighter and sleep MORE than 8 hours. I still don't believe all the successful people (eg Schwarzenegger) who claim to sleep less than 8, especially athletes. I still drink a bunch of caffeinated black tea, but it's not even close to coffee/energy drinks.
No point to this other than "Don't drink energy drinks, they are probably worse than coke".
Last note - the military studied caffeine pills since they control ideally for dose. Maybe something to consider not to stain teeth and standardize if you HAVE to have your coffee.