As someone who struggles with fatigue due to being in recovery from a liver transplant and on strong medications to suppress my immune system, I was recommended these, to increase my energy levels. I've only tried half a tablet so far but was impressed by the increase in motivation, creativity, productivity and enthusiasm for life. I would estimate a five hour build time so taking at lunchtime meant I struggled to sleep but still had some interesting ideas. Based on recommendations I am now waiting three days before taking anymore and have had a slight drop in mood - almost a down - but that could just be due to the fatigue hitting me hard again after that initial high. As someone who lack energy almost constantly this helped focus my mind and the only concern I would have would be long term effects of taking something this mind and energy altering. However - a life like the one I lead you don't know how long you have, you don't know what tomorrow will bring, and wouldn't you live best life now?