Fluid mattress assembly with check valves

The present invention relates to a mattress, a mattress overlay, or a mattress replacement assembly including an air cushion having air zones for supporting a person, and to a pressure control assembly for controlling the pressure of pressurized fluid contained by the air zones of the air cushion. The present invention further relates to a mattress assembly including a check valve configured to control air flow between a central support portion and a side bolster. A mattress assembly including an inflatable central support portion and a side bolster. A check valve is configured to prevent fluid flow from at least a portion of the side bolster to the central support portion.