I used to get leg spasms during the night too. They started after my son was born. I was experiencing a lot of anxiety after being put on bed rest in my seventh month. After he was born, I don't think I was eating well and with having a new born nursing, I believe I had just depleted my body of essential nutrients and was really stressed out. They went away after I weaned my son.

I would try taking extra calcium and magnesium and see if that helps. Here is a website that might give you some insight.

http://www.acu-cell.com/dis-mus.html