A lot of people are unaware of what I'm about to tell you. And this is why for me personally, as I live in the tropics currently, you'll almost NEVER see me getting sunlight from ~10 AM — 3 PM. Same principles apply for hot, summer days with strong UV light. There's a gene variant called TYR R402Q, with a worldwide allele frequency of about 25% that is higher in European populations (around 36.4%) - this means over one third of European ancestry has this gene. And what does it mean? It means your tyrosinase enzyme (the rate-limiting step of melanogenesis) is thermolabile and it collapses in heat. — At 31°C = 75% loss of its activity — At 37°C = becomes completely deactivated Tropics and strong summer sunlight have the potential to encompass the above. Humidity also indirectly increases heat retention by reducing the vapour pressure gradient that drives sweat evaporation from the skin. UVA/UVB light can directly get dissipated as heat on the skin. Melanin ironically plays a role in this, but to what degree is somewhat unknown due to its incredible semiconductive capabilities (usually via the conversion of light into bio-electricity). UV light also degrades collagen, so there needs to be an emphasis on infrared light exposure (shade/indirect sunlight, sunrise/sunset), supporting inflammation/oxidative stress, DARKNESS at night, and the necessary cofactors to synthesize, crosslink, hydrate, and properly turnover collagen (as seen here — xitter.cf/jack_schroder_/status/…) This is essentially telling Fitzpatrick types 1, 2, and maybe to a degree 3, that direct midday sunlight exposure in excessive amounts may not be beneficial. Despite what people tell you. More is NOT always better. I was wrong about this, as I learned from others in the space with dogmatism around excessive sunlight exposure. But yes, sunlight is still fundamental to life. Just use it properly. People in the tropics are Fitzpatrick skin type 4/5/6/7 for a reason. Natives at subtropical/Mediterranean zones are also like this for a reason. This is something that almost NO ONE speaks about. @ChrisMasterjohn touches on this in his article from a few years ago on Substack: Hair Graying? Relax in the COLD