The evidence says it is a waste of money. One of the largest frauds on the suppliment industry. If you can convince yourself that it works, go ahead and use it though, the mind is a powerful tool. Personally, I find telling myself drinking a glass of water before bed will triple my rate of muscle growth, works just as well. The power of suppliments like zma is in their placebo effect, so actually its just a matter of believing it will work.