I used to wake up every night with leg cramps, sometimes 2-3 times. I was on a diuretic at the time which I am positive was the reason. It was the potassium-sparing kind and I still got them. I'd get them in the front muscles too and my foot would curl up involuntarily towards my shin, it was terrible. Sometimes my toes would also cramp up and curl, those were the worst. My DH would run into the room to find me on the floor, sobbing! I can really feel your pain.
I would recommend this, if you are on a diuretic, find a way to get off! (Low carbing acts as a diuretic, that's why I think you get them more while low carbing) Take calcium, magnesium, and potassium as suggested previously. Light salt was suggested to me.
Be very careful about stretching. the ones I get most happen after I stretch my leg muscles out while sleeping! It seems odd, I know.
B complex vitamins has also been suggested. Here's the article:
http://www.wholehealthmd.com/news/v...513,823,00.html

I hope you can get rid of them soon, they are just awful.

Sheri