mizzouHHR

I owned a 1999 Grand am before my HHR and after a couple of years I noticed the clear headlight covers were "frosted" over and looked terrible. Looking closely it was cracked to the point it was no longer clear. I was wondering if anything can be done to prevent, or at least prolong the affect of the sun damaging the covers? Should I wax the plastic? Would some kind of light tint help?