Sunlight does seem to correlate with reduced mortality, and there is speculation that the benefit is actually due to nitric oxide.
The reduction in mortality remains after controlling for level of exercise. Also, using sunbeds and sunbathing while on holiday is associated with reduced mortality, at least in this large study in Sweden:
Source?
Every article/discussion that shows up here suggests the jury is still out in this as well.
- High incidence of MS in northern hemisphere compared to low incidence near the equator. http://www.bandolier.org.uk/booth/neurol/MSgeog.html
- Better outcome for skin cancer patients if diagnosed going into summer vs winter. https://onlinelibrary.wiley.com/doi/abs/10.1111/dth.13625
There's a decent article on the subject on nih.gov here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2290997/
And another by Harvard here: https://www.health.harvard.edu/diseases-and-conditions/benef...