A mattress arrangement, such as a bed arrangement, is disclosed, comprising an upper mattress and optionally an lower mattress. The mattresses are preferably pocket spring mattresses. A support structure is arranged beneath the upper mattress, and comprises at least one flexible elongate element arranged to extend between two holding elements arranged at opposite sides of at least one variable zone in the bed arrangement. A retraction device is further arranged to control the slack of said flexible elongate element(s) by controlling the length of the flexible elongate element(s) being provided between the holding elements. Hereby, the height and/or firmness of the bed arrangement is controlled in the variable zone(s).