You may be interested in the following video, where a quadruple board certified doc reviews relevant literature regarding sun exposure (and the critical wavelengths involved) and various facets of health: https://youtu.be/5YV_iKnzDRg

The review paper that ties many different findings from different fields (optics, endocrinology, circadian rhythms...) together with an audacious spoonful of hypothesizing is this: http://melatonin-research.net/index.php/MR/article/view/19/2...