NADH is a reduced form of B3 - niacin. If you google it , you can find more info. Over 10 years ago I took 20 mg. a day and after about a week had a noticeable increase in energy. It was great, and it lasted about 10 days and then just stopped. It was pricey - about $70 a month at that dose (I think it's gone down in price) but it just stopped boosting my energy. I don't know why. Otherwise I would have stayed with it. It does help some people with energy so I think it's worth a try. And I had to take 20 mg. to notice any effect - less did nothing for me. I've read that enteric coated is the best kind so it won't get destroyed by stomach acid, which may or may not be true.
I now take regular niacin, which helps me with sleep, although it doesn't increase my energy. And I don't know why the NADH boosted my energy so much (albeit temporarily) and regular niacin doesn't.
Here's a link to an article:
http://www.nadh-priceinfo.com/NADH_possible_benefit_CFS_FM.cfm
So sort of the like the P-5-P, I think it's worth a try to see if it helps. It would be very interesting to find out why certain things have increased my energy and stopped the crashing (PEM), only to stop working generally in about a week. In 2002 taking 2,000 mg. of l-carnitine gave me a great boost, for about a week, and then stopped.
It's a mystery! which I hope is solved one day -
Mary