A mattress comprises a mattress body (2, 3, 14) made of a resilient material, such as foam rubber, and a covering (12) which is fixed to the mattress body (2, 3, 14), such as a moisture-impermeable covering. The mattress body has at least two adjoining mattress body sections (2, 3, 14) which have mutually facing boundary surfaces (4, 5； 6, 7), to which boundary surfaces (4, 5； 6, 7) a covering (12) is likewise fixedly fitted. The covering (12) of at least one (14) of the mattress body sections has a substantially airtight casing (15) which is connected to an air connection (17).
