Ultra violet
Lance Kennedy - 31st August 2026
We all know the old (and true) slogan about moderation in all things. Rather too often, excess is harmful. This applies to ultra violet radiation on human skin, mostly meaning sunlight.
There was an article about this in Scientific American about 6 months ago. It showed how modest doses of ultra violet on human skin suppressed the immune response. This means that people with autoimmune illnesses, such as psoriasis and even multiple sclerosis, can achieve great benefit by treating themselves with that radiation, either with a UV lamp or by exposure to sunshine.
I tried to discuss this with our family doctor, but he was totally closed to the idea. He told me about the terrible harms, such as melanoma, from UV exposure. What he did not realise, and refused to consider, was that this harm came from excess.
There is now a published book on the benefits of modest doses of UV on human skin, called “In Defense of Sunlight” by Rowan Jacobsen, and published by Scribner. While I have not read this book, there was a detailed review in New Scientist magazine, 25 July 2026, pages 24 and 25. The book is based on solid medical research (as was the Scientific American article). Here are some of the benefits researchers have uncovered.
-
Vitamin D. While it is well known that exposure of human skin to sunlight leads to more vitamin D, what is not so well known is that most of the benefits of vitamin D are not created by taking vitamin D tablets. Sunlight or UV is needed for the full range of benefits. The most important of these is a reduction in incidence of heart attacks and stroke. Since there are 100 times as many deaths from this as from melanoma, that alone justified increasing exposure to sunlight or UV lamps.
-
Nitric oxide. This is also manufactured by human skin under UV, and released into the blood. Nitric oxide is a signalling molecule that causes veins to dilate. This leads to a drop in blood pressure. People who sunbathe exhibit a drop in blood pressure.
-
Endorphins. This exposure leads to an increase in endorphins in the body. No surprise that sunbathing is pleasurable!
-
Exposure releases metabolites that suppress the immune system. This reduces incidence of a range of autoimmune conditions, including arthritis and multiple sclerosis. What I found interesting is that people with the skin condition psoriasis who get UV on one side of their body get a reduction in symptoms all over the body, including places where the skin has not been exposed. Metabolites pass through the blood to benefit every part of the body.
Obviously we cannot go out and spend six hours in the summer sun. Better advice is to expose ourselves for no more than 30 minutes in the morning or late afternoon, when the sun is less fierce.
If we look at these findings from the viewpoint of human evolution, it makes great sense. My ancestors just a few thousand years ago had very dark skin. But they evolved the white skin we have now. Why?
It can also be argued that the human love of sunshine has evolved because it is good for us.
Modest exposure can be and should be recommended for its myriad benefits.