It's remarkable how much attention is given to the quantity of the desirable Sun exposure, and how little thought is spent on the quality of the light.

Absent sunscreen the UV-heavy mid-day Sun in the tropics gives me a sunburn in 15 minutes, while a morning exposure at the same locale remains perfectly safe for all the three hours that the morning lasts. The turning point is when the Sun crosses 45% boundary (when a match stuck in the sand becomes taller than its shadow), so my schedule is beach-time 6-9am and 3-6pm, while the rest of the time is spent sleeping, eating, working, and sightseeing.

I wish I could sell you some dietary supplement with this fantastic advice, but none is needed. Well, maybe a branded box of matches is in order?..