Alternating pressure bed

An alternating pressure bed, comprising:

• a mattress and a mechanism for continually varying the relative level of pressure of the mattress against a person lying on the mattress from one region of contact to another, to prevent prolonged high pressure against fixed areas that can hinder blood circulation and lead to ailments such as pressure sores
• wherein the bed includes first and second sets of closely spaced rollers mounted in a roller frame to be mutually parallel and co-planar along a preferably horizontal plane and each rotatable about its individual longitudinal axis, and a first drive mechanism for rotating each of the rollers in the first set in a clockwise direction and a second drive mechanism for rotating each of the rollers in the second set in a counter-clockwise direction, and wherein a mattress shielding sheet extends across and rests on the rollers, and a mattress extends across and rests on the mattress shielding sheet, and each said roller has at least one surface protrusion, such that when the roller is rotated the protrusion applies alternating and varying upward pressure against the mattress shielding sheet and therefore against the mattress and a person resting on the mattress.