2008 GMC Sierra 1500 Pickup Owner's Manual - Page 12

Head Restraints Pull the head restraint up to raise it. To lower the head restraint, press the release button (A), located on the top of the seatback, while you push the head restraint down. The front seats may have head restraints that also tilt forward and rearward. To tilt the head restraint, grasp the top of the restraint while pressing the button (B), located on the inboard side of the head restraint, and move it forward or rearward until the desired locking position is reached. Try to move the head restraint after the button is released to make sure that it is locked in place. The second row seats may have head rests that can be adjusted up and down, but they do not tilt. Adjust the head restraint so that the top of the restraint is at the same height as the top of the occupant's head. This position reduces the chance of a neck injury in a crash. 1-8