I've been looking into my pre-workout supplements and I've noticed that most of the ones I've used, and have benefited most with, have some niacin in it. I've always enjoyed them cuz they all gave me that jittery sensation after taking them. Figured that meant that I was ready to workout! But now I'm curious, cuz I've been reading about it a little bit. I read that the jitters are a side effect and that it actually makes you fatigued. What's its main benefit in a pre-workout or even by itself?