A bed sheet 30 is formed from two superposed layers of plastics material joined by welding along side margins 31 and 32 and at each end 31a and 32a. This then forms a sealed chamber. The sides 31 and 32 may include spaced pads or eyelets 33 for securing straps. The central part of the sheet 30 has a matrix of circular weld zones 34 which join together opposed portions of each side of the sheet with the spaces between the welds forming air-filled passageways. A characteristic is the wide spacing between each weld zone and the relative flatness of the air filled capsules thus formed. The capsules may be air-filled and sealed but in a preferred version each capsule is connected to an adjacent neighbour by an integral air duct thus permitting air to flow and pressure to equalise between the capsules when subject to compression. For storage the capsules may be deflated and inflated as required for use through an air inlet valve 35.