An active mattress may include a top panel, a bottom panel and multiple side panels. One or more of the side panels are zippered together, The un-zippered side panels fixedly connect the top and bottom portions of the side panels. In another embodiment, an inflatable volume is integrated into the bottom panel. Alternatively, the inflatable volume may be integrated with a separate detachable cover and attached to the bottom panel by conventional means. The various configurations of the encasement allows a mattress to be easily rotated, installed, or removed. Optional straps may be provided, fixedly attached to the encasement, to allow the encasement to be snugged against the mattress. This enables the encasement to be used with a relatively wide range of mattress sizes and still provide a snug fit.