Headrest for automobile seats

The headrest (10) has a support surface for the head of the passenger which can be displaced linearly relative to the main body (11) of the headrest, for forwards movement in the direction of the head, upon release of a tensioned mechanical spring (22). The movement of the support surface is guided by at least one elongate cylindrical guide element (20) for movement of a carriage (23) to which the support surface is attached, the spring (22) acting against the carriage which is retained by a releasable latch and a releasable coupling between the carriage and the main body of the headrest.