When I lived in Arizona I had the same situation. The Arizona flag depicts a rising star with its rays for a reason. The rising sun out there pierces through the skull. I live on the east coast now and it's not nearly as bad. Dark mirrored polarized sunglasses and a cycling cap with the visor and a helmet is how I dealt with it in Arizona. I also rode with a Take-A-Look mirror. It's a must. Why? Because drivers were blinded by the light also and I had to be able to see what they were doing coming up behind me.