I personally don't drink any caffeine at all, but I wanted to try those 5 Hour Energy drinks they always have on the counters at 7-11 so I picked one up. A couple of days later, I barely got any sleep and when I realized my head was falling while I was at work I decided to take it. It actually seemed to work pretty well at first, but then I was walking through Walmart later in the day and I noticed I felt really tired but I had a bunch of energy at the same time. Kinda like a high I guess. Anyway, that was my experience with it.