An active headrest (10) which is suitable for use with a seat (22) and for selectively supporting the head (12) of an occupant, wherein the head restraint (10) comprising: an outer shell (18) defining an inner space (18c) and an outer surface (18a) which is adapted to communicate with the head (12) of the occupant into engagement; is an actuator (14) within the chamber (18c) arranged and operable to adjust the distance or the engagement between the surface (18a) and the head (12), wherein the actuator (14), a linkage system (16) includes having at least one selectively extendable rod (32) pivotally connected to the seat (22) and the shell (18) is coupled, characterized, in that comprises the actuator (14) further comprises an element (14a) of an active material with the arm (32) is drivingly coupled, so as to effect selective, that the arm (32) pivots when the element (14a) an activation signal is exposed to or occluded from; and that a power source (58) is provided which is communicatively coupled to the actuator (14) and operable to generate the signal; wherein the actuator (14) further comprises a ratchet (42) and pawl (40) that are selectively engaged and are designed to allow the head restraint (10) moves in translation in a first direction, and a translation in the to prevent the opposite direction when they are engaged, wherein the ratchet (42) has a pivoting sector, the outer teeth defined, and form the at least one arm (32) and the ratchet (42) has an integral structure that moves coincident translatory ,