Hi Monte; the Magnesium I use now is only to be obtained in Scandinavia I am afraid; but it is a mix of citrate, malate and aspartate. No fillers only cellulose capsule.
I take a pinch of borax (approx 10-20 mg of boron)in the evenings (not every day, maybe 2-3 days a week) with 600 mg of magnesium almost daily. I noticed better sleep within days.
Boron makes the body retain magnesium + balance the calcium-magnesium.
One of my earlier long time problems was insomnia, and as soon I have a stressed period I can have a touch of it coming back, so I try to stay ahead of it with supplements and other stuff.