ZMA is one of my favorite magnesium-based sleep supplements; generally, I’ve had the most success with True Athlete’s ZMA with Theanine formulation, which combines the standard ZMA stack in precise dosages with theanine, a calming amino acid.
Overall, ZMA gives me a more “intense” rest than Natural Calm. Occasionally, it also contributes to very vivid, sometimes strange dreams when I take it — but overall, I’ve found it helps give me a very deep sleep and a sense of rest that I really like, especially when recovering from exercise. It was originally developed for athletic recovery, and while its benefits there are somewhat controversial, I’m a fan of its effect on sleep.
Because the rest I get from ZMA is deeper than when supplementing with just magnesium, I generally don’t take it quite as often as something like Natural Calm. But I’ve never experienced any bad side-effects from taking it multiple nights in a row or multiple nights in a week (up to four), though I do dream vividly on it.
I have several friends who are very athletic — endurance athletes especially — who swear by ZMA and take it almost every night when they’re training. A few cycle off it and don’t take it on the weekends, or may take a week off entirely, which they tell me helps them experience a greater sense of deep rest upon taking it again after the break.
As with Natural Calm, I’d recommend starting off with something less than the normal dose (3 pills for men and 2 for women with the True Athlete formulation) and seeing how your react; one or two pills may be enough, but some of the larger guys I know get the best results from the full male dose of three pills.
With pretty much any sleep supplement (including the ones I really like, like ZMA with Theanine) I recommend occasionally cycling off in order to allow your body to reset its baseline (one week a month or two weeks every two months has worked well for me). That’ll also allow you to really assess how it’s impact your rest and recovery!