An apparatus for supporting a patient, such as a hospital bed, is provided. The apparatus includes a patient support surface and at least one fluid containing bladder. A pressure control assembly is operably coupled with the bladder. When the fluid pressure within the bladder falls outside of an acceptable range of pressure values, the active adjustment of the pressure within the bladder is initiated by the pressure control assembly if the pressure does not return to the acceptable range of pressure values within a time period, e.g., a time delay, that has a variable length.