I don't know about being able to sleep wherever I am, but when I'm in good health, one of the important things that happens is that I need less sleep overall, and do take less time to fall asleep.
This is amazing as even without getting into the "quality of life" stuff, it gives me something like an extra hour every day, which is huge over the course of a life.
I've recently been following a variation of anabology's "Honey Diet" (mostly, I don't eat any fat, protein, or starch until dinner) which has pushed the needle in this direction.