My quality of life improved by a significant amount when I started supplementing magnesium. Better sleep and a bunch of other things. It's actually scary how much of a difference something so simple (and cheap) made.
In the water that I drink in the morning I dissolve small quantities of powders of magnesium bisglycinate and potassium citrate.
Before starting to do this, after days with more intense physical effort, I frequently had nocturnal leg cramps. Since I began taking this regularly, I never had leg cramps again.
I also say for me because if you already have good levels of magnesium in your diet, it will have nothing to improve.
You are welcome to review his methodology and see if it still seems like the placebo effect.