Mattresses including a chassis core including a rigid or semi-rigid base sheet; a plurality of flat springs spaced apart from one another in parallel rows, wherein each one of the plurality of flat springs comprises a first terminal end, a second terminal end, and a flexible arcuate member extending from the first terminal end to the second terminal end, and wherein a center of an arc defined by the arcuate member is fixedly attached to the rigid base sheet; a body support disk disposed on each one of the first and second terminal ends. The body support disk supports the load of an individual. In some embodiments, the body support disk is pivotably connected to each terminal end.