Great at first, but too soft overnight

This may be particular to me, but I was hoping for a bit more firmness from this hybrid mattress. I do love the soft, plush outer layer. It is very comfortable when you first get in, and it has relieved some pressure-point problems I was having with my old traditional spring mattress, but I still have back pain issues at night and need to frequently re-position myself because I often feel as though the support is not quite firm enough.