I find the light of the midday sun during the high-sun season intolerable, even when there are thin clouds in the sky. If I must be in it, my eyes are tightly shut, opening only for little peeks just enough to not walk into things. I will go to great lengths to avoid this painfully bright light, affecting what side of the street I walk on, what side of the train I sit on and whether I deviate from my preference of facing forward, whether I get off at the Tube station just after rather than just before my destination so the sun is at my back, etc. If it were overcast but not raining all summer, with sunlight only during the early morning and late evening, I would be perfectly happy.
Not only is the bright midday light bothersome, the heat of direct sunlight is excessive to me at all times except right around sunrise or sunset, or near the winter solstice when the sun is below the treetops most of the day. And the UV is murder even in midwinter. All in all, the sun is not my friend. However, I cannot be completely nocturnal - as daylight fades, all of my sensory sensitivities heighten markedly, and the only opportunity available for sleeping is consistently the second half of the darkness hours.