This invention relates to a pressure relieving mattress including an elongate support 11 having a base 12, a pressure relieving overlay 15 and an inflatable inlay 16. The inlay 16 has a plurality of laterally extending inflatable cells 23. At least some of the cells, in at least their un-inflated state, have an inflatable volume which is wider adjacent its ends than its mid portion. This reduces the likelihood of gaps appearing between the pressure overlay and the walls of the tray.
