My dad commented how Deena and Joan were both wearing light-colored hats at the Trials. There were a couple of other seasoned marathoners wearing hats, with or without sunglasses. Does a light-colored hat really make a difference when it's hot/sunny?
What about sunglasses. He thinks they obstruct your vision and could hinder performance, but I contend they help your face relax. So is it a compromise (helps and hurts)? Would a hat, alone, be a better choice?