The primary function of headrests in vehicles is safety: they're made to reduce whiplash, an unpleasant side effect of the rearward movement of the head and neck that occurs during a rear impact.

How do headrests work physics?

When a vehicle is struck from the rear and pushed forward, the vehicle seats push the occupants forward as well. Due to the physics of your body, your head will likely lag behind the movement of your torso, which causes your neck to bend back and stretch.

How do headrests prevent whiplash?

Whiplash can cause lasting distress and discomfort, but a properly configured head restraint system can reduce or even prevent such an injury. ... Head restraints are designed to restrict head movement during a rear-impact collision and reduce the chance of neck and shoulder injury.