NADH is really helpful for me, but not if I take it all the time. I take 5 mg (1/2 tab) daily, but if I'm going to have a big day I double that. But I do so with caution: while I often feel really good, maybe even great, on those rare days 10 mg days, I have to be careful to not over-do activity or I'll have a huge crash. To achieve something like Christmas day with extending family (which includes a 90 min. drive each way), I'll take 10 mg the day before, day of, and day after, but again if my over-all activity level has been too much I'll have a huge crash lasting for weeks. I have to be conscious of simply enjoying the day more, not doing more than I would without taking it. Those good days tempt me to take it at the higher dose all the time but if I do it will stop working and then I won't have that helpful boost when I need it. I've been reading up on this lately and if you search at PubMed you'll find one study of NADH with CFS that was for 48 months, and many people felt quite a bit better in ll symptoms for the first third of the study but then got worse. I've read other things about pulsing the dose, taking a week off every month, and I tried that for a while, but for me this 5 mg daily/10 mg for big days works best. It is sad to find something that can provoke a good day but to learn, over time, that it's temporary. The first few times this happened I was so hopeful I'd turned a corner, started looking into travel and grad school, but neither were to be. Since then, a good day here and there is still great, and I'd be glad if this proves helpful for anyone else.