A mattress for use on a bed frame has a lower body section 42 and a upper body section 40. The mattress upper body section is orientation adjustable in as a function of the orientation of the upper body section of the frame upon which the mattress rests. At least part 60 of the mattress lower body section is profile adjustable as a function of the orientation of the mattress upper body section without being dependent on profile adjustment of the lower body section of the frame. A mattress replacement system includes a mattress having an orientation adjustable upper body section and a lower body section. The mattress replacement system also includes an angular orientation sensor 58 for determining the orientation of the upper body section. At least part 60 of the mattress lower body section is profile adjustable in response to the determined orientation of the mattress upper body section.