If you're talking about those foam mattresses that supposedly conform to the shape of your body, my sister had one and gave it up. She's always looked normal to me, but she claims she has a curvature in her spine and that the foam mattress was exacerbating the problem. She went back to the standard coil spring mattress she always had and she says it's much better for her. I really don't know that much about it, but she said that it wasn't good for her back. I think she still has it.