I agree. Sunlight is also a mood elevator if it's at the beach with lots of palm trees and a tall cool glass of fresh coconut milk, mango, and pineapple drink with a little plastic monkey and an umbrella hanging off the side of the glass. (or something close)
It isn't the best but the ultraviolet light kills some pathogens. I have read that poor countries filter their water, bottle it, and set it in sunlight to kill pathogens that make people sick.