Not more cooling. As I mentioned earlier, white sunsleeves, particularly PI (really, really white) reflect more sun than does naked skin. White garments make a big difference. To see how big, put a white and some event jersey like so many cyclists wear, out in the direct sun for a while, then feel them. Even yellow is hotter. One can feel the differences in a printed pattern.

As L. Francis Herreshoff said, "There are only two colors to paint a boat, white and black, and only a fool would paint one black." For the above reason.