I don't want to get into a debate here, but Poliquin wrote this about ZMA:
"One of those things you can control is your low level of zinc. I have never seen normal levels of zinc and magnesium with my first time clients. Say what you will about Victor Conte, but when he came out with ZMA, he solved America's two greatest deficiencies: zinc and magnesium.
Restoring magnesium level is a bit more complicated than just using pure ZMA. Restoring zinc is fairly easy; it really doesn't take that long. Restoring magnesium levels can sometimes take four times longer. If you're deficient in magnesium then you can't sleep well. About 68% of the American population complains of some sort of sleep disorder, and that's due largely to magnesium levels. That's why people who start taking ZMA will sleep better.
Some studies will show that 58% of the population is zinc and magnesium deficient. Other studies show 75%. But I can tell you that with the athletic population or with anyone who exercises four or five times a week, it's 100%. Usually you can correct a zinc deficiency in a non-athlete at 30mg a day for eight weeks. With the athletic population, we sometimes need to bring the dose up to 180mg a day for two months and then start to taper.
How can you tell if you're deficient? Well, you most likely are! But there is a very cheap test you can do to be sure. You buy this stuff called Zinc Tally, which is basically liquid zinc. You put it in your mouth and if you're normal it tastes like a liquefied metal car bumper. But when we ask the athletes who come into my centers what it tastes like, they'll say it tastes like water. They're so deficient they can't perceive there's any zinc in the solution.
Once they rebuild their zinc level, they can barely keep the Zinc Tally in their mouth. If they have to practically spit it out after eight weeks, then we know their zinc levels are normal.
In short, although age 31 is when we see things start to "fall apart," many of these things can be prevented by maximizing androgen levels through the means discussed above."
I started doing ZMA simply because Shaf (Steve Shafley) recommended it. I found my dreams instantly became more vivid. I NEVER trust research as it usually just tells us what we know (Lifting weights will make you stronger), but I will try things that a friend recommends. In fact, I had a great lunch once time with a guy named Robb Wolf and he taught me that my chicken eating was good for me...
So, I take ZMA because of my experiences...