Intense/bright sun can nearly LITERALLY paralyze my dad ANYTIME of day, even w a cap on. We practically sprint to the car/bldg for shelter. I don't understand my dad's reaction. He has fallen a few times (one incld major dislocation of upper jaw, requiring surgery) but never diagnosed with head injuries, although once was discovered passed out on sidewalk. He was apparently trying to escape hot sun, had locked his keys in car and was trying to get to the keys.