“Cavemen” weren’t really men or women who lived their lives in caves all the time. Most of the day, they were in the great outdoors pursuing their various survival tasks. Regular exposure to sun provided lots of vitamin D, an all-important vitamin which they could not easily obtain from food and which their bodies could not manufacture without direct sunlight.
Contrary to the“Common Wisdom” dispensed by dermatologists (who suggest you shun the sun), the Primal Blueprint would insist that you get some direct sunlight every day. Certainly not so much that you come close to burning, but definitely enough to prompt your body to make the all-important vitamin D and to support the mood-lifting benefits. A slight tan is a good indicator that you have maintained adequate Vitamin D levels. Natural sunlight also has a powerful mood-elevating effect, which can enhance productivity at work and in interpersonal interactions.