Also don't forget to switch your inside rear-view mirror to the Night or Auto Dim setting, which darkens the mirror to prevent glare.
Clean and Adjust Your Exterior Mirrors
Dirty mirrors reflect the lights from cars behind you in a wider, diffused shape that can produce glare in your eyes, so clean them up. Also, aim the exterior mirrors so that you can move your head out of the path of lights reflected in them. We like to aim them downward just slightly. That way, you can see cars behind you by tipping your head slightly forward, but you keep the other car's headlights out of your eyes—and prevent them from temporarily blinding you with their high beams.