This invention is directed to a mattress assembly for use in a sofa sleeper. The mattress assembly has an outer shell and an inner support received within the outer shell. The shell includes a lower panel, a sidewall, and a cover that fit together to form a cavity to receive the inner support. The inner support includes an air bladder and an innerspring portion. The air bladder has a valve that is adapted to allow air into and out of the bladder. The air bladder is deflated when the mattress is stored to provide a compact configuration.