I have been taking 5 mg daily--first thing in the morning--and after a period of perhaps 2 weeks during which I noticed nothing, it became apparent that I had more energy, was walking better and had a better 'attitude' generally. I don't know if NADH is responsible for all the improvement, but suspect that it may be credited at least for the increase in energy and decrease in depression. I also take CQ10. It's really difficult to pin down benefits of one over the other. Clare Wilson