Mattress : Things to check

Pocketed Spring :

a) 'coil count' (no. of springs in the mattress)
b) 'coil gauge' (thickness of the springs inside)
A good-quality full-sized mattress has a wire gauge of between 12.75 (more firm) and 15 (less firm).

Waterbed :

Beginning while I first sleep on my waterbed. I had a sound sleep everynite. But after 5mths of sleeping on my waterbed. I starts to feel ache on my back and neck everyday when I wake up.