The control unit has built in software that enables optimal, patient-customised inner cushion pressure settings based on the Body Mass Index of each patient. Using one control unit, for both mattresses and all pressure levels, lowers storage costs, service and training requirements. The system, which is virtually noise and vibration-free, allows high-quality resting comfort and enhances the quality of life of bedridden patients. When the patient changes positions, the automatic pressure adaptation feature quickly modifies the pressure required in the overlay.