I've been using ZMA since the late 1990's for myself and clients. It clearly speeds recovery from all kinds of stress. It seems to help people not get clods and flu, or to recover quickly form colds or flu. It is one of the few supplements I recommend, the other two being fish oil and Dr, Schulze's superfood. ZMA provides a great bang for the buck. I only take it in time of stress or in the days leading up to times of stress, if possible. Also the dose is usually 3 capsules, but you can develop a sense of when you need only two or one. This way one jar can last a long time. Evan Strong, my athlete headed for the Olympics is taking ZMA and he reports he can feel a powerful improvement in recovery from races and training on the slopes. Evan is always experimenting with fancy and expensive, organic and natural superfoods, plant medicines and adaptogenic herbs. He is an expert on the subject. He really appreciates the cheap, simple effectiveness of ZMA. I always tell people, why not try it? It's super cheap. If you don't like I'll buy it off you and use it myself. One thing to watch for: Certain brands see the supplement as a sleep aid and add valerian. These versions do not seem to work. Maybe the valerian throws it off, or the product has some other quality problem. NOW brand has proven to be my favorite.