Abstract: A body rest such as a bed with means incorporated for avoiding the development of pressure sores (decubitus ulcer) caused by prolonged local pressure against a patient's body. The bed comprises: a matrix of freely vertical displaceable supports, in the form of free-floating, pressurized air-supported pistons, constituting together the continuous couch surface of the bed. The pressure exerted by the patient's body sections against their respective support pistons is constantly measured. Valves are provided associated with and controlling the discharge of the air from the piston chambers under the pressure applied to each one of the respective support pistons. After a preset time and level of pressure prevailing within a given piston chamber, a fixed amount of air is discharged, thereby partly relieving the pressure and causing the downward displacement of the respective piston. At the end of the cycle, all the pistons are brought back to their initial, common high level.