A bed configured to contain a subject, such as a human infant is disclosed. The bed includes a womb-shaped bumper capable of constricting or squeezing the subject. The bumper includes two opposed side portions, at least one void in at least one of the opposed side portions, and at least one mesh portion enclosing the void. The bumper is adjustable between a constricting configuration and a non-constricting configuration. An adjustment mechanism, and optionally, a fastener may be used to maintain the bumper in the constricting configuration.