I run a sports nutrition store and I think very highly of ZMA. Here is what it is...its a combo of zinc and magnesium and most likely youll find some B-6 thrown in there for good measure. Zinc is a mineral that plays a pretty big part in the regulation of tissue repair and cell growth and helps support your immune system. Magnesium is very important in keeping your electrolytes balanced, producing energy, and supporting neuromuscular function. When you train you often lose these minerals so its important to replace them. Some forms of ZMA will contain Mucuna prurines which comes from a bean. These beans happen to be used for a bunch of different things but just happen to have a naturaly high concentration of L-Dopa. Ive found that when I use a ZMA with the added Mucuna I rest better at night and that is the intended purpose- enhanced recovery while sleeping and a better more restfull nights sleep. Take it before bed but make sure not to drink anything like milk or something with a high amount of calcium because that can block the absorbtion of the ZMA. Thats what I know...hope it helps.