Support device of the mattress type comprising a heterogeneous inflatable structure

A mattress has at least one inflatable top layer made up of a plurality of adjacent elements that are individually inflatable by a pneumatic inflation and pressure regulation device and at least one bottom layer supporting the top layer. The bottom layer has a recess for receiving a sensor connected to the pneumatic inflation and pressure regulation device, and making it possible to determine the pressure applied by the body of an individual bearing against the inflatable top layer and to regulate the inflation pressures of the elements of the top layer. In at least one support zone designed to support the sacrum of an individual, the top layer is made up of a plurality of inflatable elements that are of a width smaller than their height.