Sleeping arrangements effect health? (e.g. type of mattress)

JustAnotherOneOfThoseGirls

So, I've recently moved from sleeping on a mattress with springs sticking out all over the place to crashing on a sofa and was wondering whether where you sleep actually effected your health? I've noticed that since making this change (about 2 months ago) I've looked a lot healthier, although my insomnia has gotten worse. I read somewhere that the firmer the surface you're sleeping on, the better for your back and posture? Wondering whether any of this has any truth in it