Came here to link that source myself, so I'll just emphasize an important part: >Is it best to get your vitamin D from the sun? Definitely not! —David J. Leff

Came here to link that source myself, so I'll just emphasize an important part: >Is it best to get your vitamin D from the sun? Definitely not! —David J. Leffell, MD, Yale Medicine dermatologist and chief of Dermatologic Surgery That whole section is worth reading. Light may be useful in a Circadian context, but from strictly a Vitamin D point of view you're better off with a diet rich in Vitamin D, or supplementation. Unsurprisingly wild-caught salmon and pasture-raised chicken eggs yield higher Vitamin D content, but supplementation also works. If you're vegan and deprived of sunlight, then supplementation might your only viable option.