Just wanted to share my experience with magnesium. You mileage will obviously vary, but I can't take mag during the day or it will knock me out. I have to take it at night, which works out since it helps me sleep. But, I only take 300mg every other or third day, depending on how I'm feeling. I don't need much.
I think the point in taking mag is that it helps regulate relative calcium levels, which get all out of whack w/ AF.