Originally Posted by cooker

It's a public health issue, for one thing. People are pretty aware of the hazards of too much UV exposure damaging skin and increasing the risk of skin cancer, also causing cataracts and so on; but what's less appreciated is that underexposure to sunlight is also linked to a wide range of health problems. In fact underexposure may be a much bigger problem.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2290997/