Issue #36: March 23, 2026

For fifty years, the public health message around sun exposure has been consistent: cover up, apply SPF, limit your time outside. Skin cancer rates, we were told, depended on it.

Here's what nobody mentions: in that same fifty-year window, rates of depression, autoimmune disease, hormonal dysfunction, and sleep disorders have climbed steadily. And a growing body of research keeps pointing to the same overlooked variable.

Chronic sun avoidance.

The sun isn't the villain. Our relationship with it is just badly misunderstood.

☀️ It's About More Than Vitamin D

Most people, when they think sunlight and health, think vitamin D. And vitamin D matters. Roughly 40% of Americans are deficient, and that deficiency is linked to weakened immunity, poor bone density, depression, and increased cancer risk.

But reducing sunlight to vitamin D is like reducing food to calories. It misses almost everything interesting.

Sunlight is a biological signal. Your body has evolved over millions of years to use it as information, regulating hormones, syncing internal clocks, and triggering cascades of biochemical activity that simply don't happen in its absence. Remove that signal, and systems start to drift.

Here's what sunlight actually drives:

None of these come from a supplement bottle. And none of them are minor.

🕰️ The Circadian Connection

This is where most people are quietly losing, and don't know it.

Your body runs on a roughly 24-hour internal clock called the circadian rhythm. Every hormone, every organ, every cellular process is timed to this cycle. The primary way that clock gets set each day is through light, specifically morning sunlight hitting your eyes and skin.

Wake up and go straight to artificial light indoors, and your circadian clock gets a weak, confused signal. Cortisol doesn't peak properly. Melatonin suppression is delayed. Sleep pressure doesn't build the way it should. By evening, the whole system is slightly out of phase, and you feel it as grogginess, poor sleep, afternoon crashes, and mood that never quite lifts.

Morning sunlight is the reset button.

Even five to ten minutes outside within an hour of waking, no sunglasses, no window glass filtering the light, sends a clear signal that anchors the entire day's hormonal rhythm. It sounds almost too simple. The research is unambiguous.

Before I get into my own morning routine, a quick word from today's partner.

3pm crashes every day. Unexpected weight gain. Unpredictable cycles. When symptoms start piling up, your hormones and metabolic health are often part of the story.

Allara helps women understand what's really going on with comprehensive hormone and metabolic testing. Their advanced testing goes beyond the basics to measure key markers like insulin, thyroid function, reproductive hormones, and metabolic health. Whether you already have a diagnosis or are still searching for answers, Allara's care team uses your results to create a personalized treatment plan with expert medical and nutrition guidance.

They treat a wide range of women’s health conditions, including PCOS, fertility challenges, weight management, perimenopause, thyroid conditions, and more.

With Allara, you get clarity, expert support, and a personalized care plan all for as little as $0 with insurance. This isn’t about quick fixes. It’s about understanding your body and addressing the root causes.

Get started with Allara

🌡️ My Morning Practice

In spring and summer, I get outside early, usually while using my cold plunge, which sits outdoors. Morning sunlight and cold exposure at the same time. Two of the highest-leverage inputs for cortisol regulation, alertness, and mood, stacked into the same ten minutes.

It's not a complicated routine. It's just intentional.

On vacation, I take a more relaxed approach to sun protection. I've written before about the chemical concerns with conventional sunscreens, and I practice what I preach. That doesn't mean reckless exposure. It means dosed, sensible time in the sun without reflexively reaching for chemical SPF. Shade, timing, and mineral-based options when protection is genuinely needed.

The goal isn't to avoid the sun. It's to use it intelligently.

🤔 Fair Pushback — Let's Address It

A contrarian take on sunlight invites reasonable skepticism. Here are the most common objections and where the evidence actually lands.

"Sun exposure causes wrinkles and ages your skin." This one is true and worth taking seriously. Chronic UV exposure breaks down collagen and elastin over time, contributing to photoaging, fine lines, and uneven skin tone. The answer isn't to avoid the sun entirely. It's to avoid excessive exposure, particularly during peak UV hours, and to support skin health through nutrition, hydration, and antioxidants. A tan that develops gradually without burning is a very different biological event than repeated midday sun damage over decades.

"Can't I just take a vitamin D supplement?" Partly. Supplementing D3 will raise your blood levels, and if you're deficient, that matters. But the other benefits of sun exposure don't come in a capsule. Serotonin production from retinal light exposure, nitric oxide release from UVA, direct T-cell activation through the skin, and circadian entrainment from morning light are not replicated by a supplement. Vitamin D is one output of many. Supplementing it while staying indoors is like replacing one ingredient in a recipe and calling it the same dish.

"What about skin cancer?" The relationship between sun exposure and skin cancer is real but more nuanced than it's often presented. The evidence most strongly links burning, particularly in childhood and adolescence, to melanoma risk. Regular, non-burning exposure in adults tells a different story. Some research even suggests that moderate sun exposure may be protective against certain internal cancers through its vitamin D and immune effects. The goal is dose. Unprotected burning is never the answer. Neither is permanent avoidance.

🛠️ How to Actually Use Sunlight

Get morning light within an hour of waking Five to ten minutes minimum, ideally more. Outside, no sunglasses, no glass. Even on overcast days, outdoor light is significantly brighter than indoor lighting and still sets the circadian signal effectively.

Use midday sun for vitamin D UVB rays are only present when the sun is high in the sky, roughly 10am to 2pm depending on your latitude and season. A few minutes of direct skin exposure during this window, without burning, outperforms supplementation alone.

Build tolerance gradually If you've been largely sun-avoidant, your skin's melanin response is underdeveloped. Start with shorter exposures and increase over time. Burning is never the goal and counterproductive to everything here.

Protect intelligently, not reflexively For extended exposure, shade and timing are your first tools. When sunscreen is genuinely needed, mineral-based options like zinc oxide and titanium dioxide block UV without the chemical absorption concerns covered in Issue #1 of this newsletter.

💡 The Bottom Line

The sun has been painted as a threat for fifty years. The result is a population that's vitamin D deficient, circadian-disrupted, hormonally dysregulated, and cut off from one of the most powerful free inputs for human health.

Yes, too much sun damages skin over time. Yes, burning raises cancer risk. Those are real and worth managing.

But the answer to those risks is intelligent use, not wholesale avoidance. The research is clear: people who get regular, dosed sun exposure live longer, sleep better, have stronger immune systems, and carry better hormonal profiles than those who don't.

Sunlight isn't something to manage around. It's something to use deliberately.

Go outside. The science is on your side.

Until next week. Stay vital.

-Jordan Slotopolsky

📚 Sources