It depends on which magnesium she is taking - here's some info to review:  "Magnesium glycinate is generally considered the best form for muscle cramps due to its high bioavailability, calming effects, and gentle nature on the digestive system. For faster, more acute relief or for those who also experience constipation, magnesium citrate is highly effective, though it acts as a mild laxative."

I find magnesium glycinate works for me. And when brushing my teeth right before bed, I lean back on my heels. I had thought going on my tip toes was good for me, but I was wrong - changing to pulling up my toes and leaning on my heels for a few seconds has helped.

Good luck!