While we know many lupus patients are sensitive to the sun, recent discoveries are making it possible to understand exactly why sunlight causes irritation. According to the Science Daily:
"The biological mechanism of sunburn -- the reddish, painful, protective immune response from ultraviolet (UV) radiation -- is a consequence of RNA damage to skin cells, report researchers at the University of California, San Diego School of Medicine and elsewhere in the Advance Online Publication of Nature Medicine. The findings open the way to perhaps eventually blocking the inflammatory process, the scientists said, and have implications for a range of medical conditions and treatments."
Translated, this means that researches found that UV radiation can impact RNA (regulatory molecules within the cell), which is what triggers inflammation, which can contribute to a lupus flare. Per the article, "Some people have excess sensitivity to UV light, patients with lupus, for example. We are exploring if we can help them by blocking the pathway we discovered." Wouldn't that be fabulous?