Magnesium. Lots and lots of magnesium. I sleep like the dead. Frequently wake up in the same position I fall asleep in.
Get a book called The Magnesium Miracle by Carolyn Dean. You library has it for free or you can get it online for about $12.
Magnesium does hundreds of things more than fix your sleep and nearly everyone in western society is deficient. Many forms exist but Mg chloride, liquid or tablet is very well absorbed. It will take months to begin working because the areas that need it most, like the heart, will preferentially absorb it first. The book explains it all.