A method and to a mechanism for adjusting mattresses or chair beds into an operating position comprising extendable guides in which rods run, which merge in a joint pin, which interacts with pins of a mattress, which protrude from a centreline of the mattress. A parallelogram has joints, which are connected to each other through an elongated-hole guide, one joint can be moved in the elongated-hole guide, wherein the rods are articulated to the joint pin, a bushing arranged therebetween, the pin extends into a pulley having a restoring spring, on which pulley a cable is wound and fastened to the joint, at a certain height of the mattress, the cable is tensioned and the angle is reduced, the cable causes the rotation of the pulley in such a way that the mattress is rotated.