Ultraviolet light has the well known benefit of creating vitamin D. We also know that it is useful for getting rid of two toxic substances that the body can't get rid of easily without UV: bilirubin and vitamin D. Yes UV creates and destroys vitamin D and too much vitamin D is toxic (but it is almost impossible to have that much vitamin D if you get any sun at all).
Well I have always suspected that there are much more toxic and semi-toxic inorganic molecules that sunlight helps to get rid or. So I was interested to hear about the person with a rare liver condition who is given 10 hours of blue (presumably UV) light a day. Now this is interesting to me because after a blood test my doctor said I had a mild liver problem that left some junk in the blood. Is that part of the reason that my health has been much better since I've been getting regular sunshine?
We also know that sunlight is good for various skin conditions, such as psoriasis, and I also noticed that a number of little skin problems disappeared when I started getting more sunshine.
I also think that if you have high levels of vitamin D, and you avoid tropical levels of sunlight, then you won't have high risk of skin cancer. It would be nice if medical researchers looked into stuff like this, but if there's no drug then there's no money.