Very interesting question. Thank you.
The pathophysiology of photosensibility in lupus patients is related to the effect of ultraviolet radiation (UVR) on cells of the immune system. UVR stimulates lymphocytes recruitment and antibody-mediated cytotoxicity, which are involved in the pathogenesis of lupus.
The mechanisms by which ultraviolet-A (UVA) (320–...
The sunlight through the window does not stimulate vitamin D synthesis in the skin.
Sunlight and Vitamin D (PubMed):
Since glass absorbs all UVB radiation, exposure of the skin to
sunlight that passes through glass, plexiglass, and plastic will not
result in any production of vitamin D3 in the skin.
The sunlight reflected from the surfaces, ...
There are a few mechanisms at work that influence the vitamin D status for Europeans. Vitamin D is either eaten in the food, created with the help of sunlight or supplemented. Many appear to net have enough it:
Humans get vitamin D from exposure to sunlight, from their diet, and from dietary supplements. A diet high in oily fish prevents vitamin D ...
This has been a controversial question for many years. The current evidence suggests that sunscreen does block a part of Vitamin D production, but with negligible amounts.
Studies have found that by blocking ultraviolet rays, sunscreen limits
the vitamin D we produce. But the question is to what extent.
A few studies have concluded that the effect ...
As critiqued in comments, this answer possibly misrepresents the vitamin D situation, which is better described here. Proceed with suspicion!
Because of the associated cancer risk, protecting your skin from sunlight is a good idea, also when swimming, and especially by wearing UV-absorptive clothing. Sunscreen makes a huge difference too.
Ideally, people should get enough vitamin D from their food. However, that's difficult to do, Many folks don't get enough of the nutrient from dietary sources like fatty fish and fortified milk.
It's not known exactly how much time is needed in the sun to make enough vitamin D to meet the body's requirements.Ref.here
This is because there are a ...