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Multiple large cohort studies from Sweden and the United Kingdom demonstrate that individuals with active sun exposure habits have lower all-cause mortality compared to those who avoid sun exposure.[1][2][3] The landmark Melanoma in Southern Sweden (MISS) cohort study of 29,518 women followed for 20 years found that women with active sun exposure habits had a life expectancy 0.6-2.1 years longer than those who avoided sun exposure.[4] Notably, the study found that nonsmokers who avoided sun exposure had a life expectancy similar to smokers in the highest sun exposure group, suggesting that sun avoidance is a risk factor of similar magnitude to smoking.[4]
The mortality benefits appear primarily driven by reduced cardiovascular disease (CVD) and non-cancer/non-CVD deaths rather than cancer mortality.[2][3][4] While sun exposure does increase the incidence of skin cancer, it paradoxically improves overall survival and may even improve skin cancer prognosis.[5][6] Large cohort studies indicate that various measures of higher sunlight exposure are associated with improved overall life expectancy.[7]
The mechanisms extend beyond vitamin D synthesis. While higher vitamin D levels are associated with lower mortality risk, randomized trials of oral vitamin D supplementation show limited benefit, suggesting vitamin D may be a proxy rather than a mediator of sun exposure benefits.[8][9][10][1] Emerging evidence points to vitamin D-independent pathways, including photomobilization of nitric oxide from skin stores (which reduces blood pressure and cardiovascular morbidity) and activation of neuro-immune-endocrine pathways.[1][7]