For many, this is true

GM

Most melanomas occur on body parts that rarely see the sun This alone should make you pause. If full spectrum sunlight were the primary culprit, you’d expect the highest melanoma rates on chronically sun exposed areas like the face, neck, and forearms Instead, melanomas overwhelmingly appear on the trunk, thighs, and other typically covered areas That pattern doesn’t scream UV causation, it points to something deeper, like systemic chronic circadian and metabolic dysfunction

Here’s where mechanisms meet the real world results, and I love to see it because my most recent Substack article explains much of the why behind this Most think it’s impossible for Vitamin D levels to rise through a cold, “sun and UV poor” Canadian winter despite no supplementation 1. Mobilization of fat stores during cold exposure. 25(OH)D is fat-soluble and stored in body fat. Frequent cold exposure increases sympathetic tone, brown adipose tissue activation, and lipolysis, which mobilizes stored lipophilic compounds, including Vitamin D metabolites, into circulation In winter, you’re not necessarily producing new Vitamin D through skin UV-B exposure, but your body is liberating what you stored during summer, raising serum levels 2. Enhanced sulfation and circulation dynamics in cold Cold exposure upregulates hepatic sulfotransferase activity and improves peripheral circulation Sulfated Vitamin D metabolites like 25(OH)D₃-3-sulfate) are more water-dispersible and can act as a circulating reserve pool, re-entering active circulation when lipolysis and transport proteins shift Likely making more Vitamin D bioavailable or detectable in standard blood tests depending on the assay 3. Seasonal hormonal and binding protein fluctuations Vitamin D–binding protein and albumin levels are not static, they fluctuate seasonally and under stress. Cold exposure, changes in liver metabolism, and altered circadian photoperiods can shift DBP levels. A lower DBP concentration can increase the proportion of free and bioavailable 25(OH)D, which can raise measured total levels depending on the test 4. Reduced conversion to active metabolites In colder months, metabolic rates and sun exposure patterns shift. If less 25(OH)D is being converted to 1,25(OH)₂D (the active form), the circulating pool of 25(OH)D might actually RISE because less is being drawn downstream Think of it like reduced spending during hibernation, the checking account balance creeps up because withdrawals slow down 5. Circadian and photoperiod adaptations Even without external UV-B, proper light entrainment through getting AM light daily keeps the hepatic-renal axis and hormonal cascades in sync, further supporting efficient recycling and conservation of Vitamin D metabolites Circadian alignment creates more efficient Vitamin D homeostasis ••• All this points to some fascinating overlap that most people do not consider A winter rise in Vitamin D likely reflects a synergy of three processes: 1. Mobilization of stored lipophilic D metabolites through cold-induced lipolysis 2. Enzymatic reconversion of conjugated metabolites into measurable 25(OH)D 3. Endogenous biophoton UV-B photochemistry acting on cholesterol/sulfated precursors, sustaining low level Vitamin D production even in the absence of external UV-B This is why I advocate for sunbathing when the time is right, so you can build that reserve of Vitamin D metabolites In winter, especially with cold exposure and good circadian hygiene, your body liberates and conserves those stores more efficiently, oftentimes enough to increase serum Vitamin D, even without new synthesis The human animal is built for this

Maybe your Vitamin D3 levels aren’t meant to stay sky high all year Maybe, just maybe, life is built on seasonal duality, not perpetual summer Even at the equator, there’s no such thing as true perpetual summer, it’s just a different kind of rhythm. The sun might rise and set at nearly the same time year-round, but rainfall patterns, food availability, humidity, and cloud cover create their own seasonal cues that living systems have adapted to Equatorial populations still experience cycles, they’re just less about temperature and more about rain, light diffusion, and ecological shifts. The body still syncs to these environmental rhythms So the idea of keeping D3 status or any biological marker “locked in” year-round is ahistorical and biologically tone deaf Even nature’s most stable environments pulse Modern thinking treats health like a thermostat. Pick an “optimal” number and lock it in What they fail to understand is that biology is rhythmic. Vitamin D3 levels naturally rise with abundant UV-B in summer and decline through winter, mirroring changes in light, temperature, food availability, and circadian gene expression, so forth Forcing levels to remain elevated year-round through supplements or artificial UV ignores this deeper rhythm and turns you into a neurotic pain in the ass Winter is a different operating mode Just like trees shed their leaves, your physiology shifts gears.. altering hormone cascades, immune tone, and metabolic priorities. Flattening these seasonal waves may feel optimized on paper, but it often clashes with how humans actually evolved to function The point? Health isn’t about constant abundance, it’s about respecting the ebb and flow

The wise pick up on the details here Sunlight conditions the immune system, tanning beds just tan skin UV-A and blue light in the morning from the sun boost T-cell motility and immune surveillance through nitric oxide release and specific photoreceptor pathways in the skin This effect is spectrally coordinated along with circadian timing UV-A rises after dawn, alongside visible light and IR, priming immune cells to patrol tissues more effectively Tanning beds, on the other hand, blast narrow UV spectra in isolation, nearly always without the proper timing, visible light balance, or infrared context that drives this immune activation So while they may pigment the skin or raise Vitamin D with repeated use, they don’t replicate the immune tuning role of sunlight.. no sunrise gradient, no nitric oxide surge, no circadian signaling The devil is in the details here

Tanning bed salon culture is one of the strangest modern subcultures It’s built entirely around light, yet next to no one involved understands anything about light or circadian biology Instead, the entire experience gets reduced to chemical bronzers, accelerators, collagen “boosters,” and gimmicky lotions with names like “Mermaid,” “Dark 47,” and “Power Up,” all while blasting isolated UV and other wavelengths in artificial indoor environments And to call your most advanced tanning beds “full spectrum” is a joke. It’s marketing garbage They chase a tan, but completely ignore the timing, spectrum, and circadian signaling that make sunlight life giving Talk about a perfect microcosm of modern confusion. Obsessing over the appearance of a tan while completely ignoring the physiological context that makes real sunlight regenerative rather than disruptive

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