Sun-Kissed
Why Conscious Sun Exposure, Light Hygiene, and a Stable Circadian Rhythm Matter So Much
With spring comes more daylight back into our daily lives, and our bodies respond to the new light. The days grow longer, we feel more energy, want to get outside again, and instinctively crave sunshine on our skin.
This need is no accident. Natural light is far more than just brightness and warmth. It is a biological signal that influences our circadian rhythm, sleep quality, hormone regulation, and the body's own vitamin D production. For the skin especially, sunlight is particularly fascinating. It is not only our largest organ and our protective barrier to the outside world, but also the place where UVB light triggers the body's own vitamin D synthesis.
In recent years, much has been discussed about sun protection, UV radiation, and skin aging. In my view, one aspect is often overlooked: conscious, natural, and measured sunlight exposure. And by that, I mean the gradual adaptation to sunlight, practicing light hygiene, and a better understanding of how closely the sun, skin, and inner balance are connected.
That's exactly what this article is about: melatonin, vitamin D, the role of the skin, the circadian rhythm, and the question of how we can put sunlight back in a positive light.
The Sun as a Source of Life
The sun is far more than just brightness and warmth. It is the origin of life, a natural energy source, and one of the most important regulators for our bodies. Since the beginning of time, humans have depended on light—not just to see, but to function properly from within.
Natural sunlight supports numerous important processes in the body:
- It stabilizes the circadian rhythm, which directly affects energy, sleep quality, and regeneration.
Source: Blume C et al. Effects of light on human circadian rhythms, sleep and mood. Nature and Science of Sleep, 2019. https://pmc.ncbi.nlm.nih.gov/articles/PMC6751071/
- It supports hormone regulation, especially through the inner clock, melatonin release in the evening, and natural cortisol timing in the morning.
Source: Hoshino FM et al. Physiological and Pathological Role of Circadian Hormones in Endocrine Systems. International Journal of Endocrinology, 2019. https://pmc.ncbi.nlm.nih.gov/articles/PMC6781184/
- It helps regulate the cortisol rhythm. Natural light in the morning supports natural cortisol timing, which is important for wakefulness, performance, and a healthy daily cycle.
Source: Hoshino FM et al. Physiological and Pathological Role of Circadian Hormones in Endocrine Systems. International Journal of Endocrinology, 2019. https://pmc.ncbi.nlm.nih.gov/articles/PMC6781184/
- It improves energy, vitality, and mood, because sunlight is directly connected to increased serotonin activity.
Source: Lambert GW et al. Effect of sunlight and season on serotonin turnover in the brain. The Lancet, 2002. https://pubmed.ncbi.nlm.nih.gov/12241833/
- It contributes to the body's own vitamin D production, once sufficient UVB reaches the skin.
Source: Bikle DD. Vitamin D: Production, Metabolism, and Mechanism of Action. Endotext / NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK278935/
- It can expand blood vessels and support circulation by releasing nitric oxide from the skin.
Source: Liu D et al. Whole-body UVA irradiation lowers systemic blood pressure by release of nitric oxide from intracutaneous photolabile nitric oxide derivatives. Journal of Investigative Dermatology, 2014. https://pmc.ncbi.nlm.nih.gov/articles/PMC3897598/
- It indirectly influences all metabolic processes positively. A stable light-dark rhythm is closely linked with glucose control and insulin sensitivity.
Source: Mason IC et al. Light exposure during sleep impairs cardiometabolic function. Proceedings of the National Academy of Sciences, 2022. https://pmc.ncbi.nlm.nih.gov/articles/PMC8944904/
- It promotes better sleep when sufficient natural light is consumed during the day and artificial light is reduced in the evening.
Source: Blume C et al. Effects of light on human circadian rhythms, sleep and mood. Nature and Science of Sleep, 2019. https://pmc.ncbi.nlm.nih.gov/articles/PMC6751071/
At a time when much has been said about sun protection, wellness aging, and potential risks, it's easy to forget that sunlight is something natural and vital. Not something we should fear outright, but something we need to understand better and use more consciously.
For me, the problem is not the light itself, but the wrong way of dealing with it. Sun is a natural stimulus, but a highly effective one. It consists not only of heat, but of a complex light spectrum that interacts with our organism on many levels.
Figure 1: The Depth Different Components of Sunlight Penetrate into the Skin
The skin, as our body's largest organ, receives these light stimuli directly. Depending on the light component, it reacts differently to UVB, UVA, and other components of sunlight. That's exactly why it's so important not to categorize sunlight simply as "good" or "dangerous," but to view it differentiated.
Improper sun exposure can show directly in the appearance of the skin—in the form of irritation, tightness, redness, uneven skin tone, or premature wrinkle formation and skin aging. This is primarily caused by known UVA radiation.
BUT! If someone hasn't exercised for a whole year and suddenly does 200kg squats and injures themselves—who's to blame? The weight plates? Hardly. The same applies to the sun. The enemy is not the sun itself, but excess, lack of preparation, and careless handling of its power.
Figure 2: UVA Radiation and Light-Induced Skin Aging
At the same time, the skin is precisely the place where light can trigger positive processes—if we use it correctly. That's exactly why I don't believe in cultivating fear of the sun, but in learning the right way to interact with it again.
Why Light is Indispensable for Our Bodies
Our body follows an internal clock, called the circadian rhythm. This internal 24-hour rhythm influences when we feel awake and tired, how hormones change throughout the day, and how well we regenerate at night. One of the most important external regulators of this internal clock is light. It helps the body distinguish clearly between day and night.
Particularly important is the interplay between light and melatonin.
"It is a hormone that your brain produces in response to darkness."
Source: NCCIH (NIH), Melatonin: What You Need To Know
https://www.nccih.nih.gov/health/melatonin-what-you-need-to-know
Melatonin is often called the sleep hormone, but it's actually primarily a darkness hormone that is released in response to darkness and signals the body that the phase of rest is beginning. Blue light after sunset, whether artificial light or screen light, can delay this release, even inhibit it. That's why good night's rest doesn't start when you go to bed, but with healthy light management throughout the day.
The pineal gland is responsible for 5% of melatonin synthesis. The remaining 95% is synthesized outside the pineal gland in many tissues of the body locally, thanks to sunlight. Extra-pineal production mainly serves cellular protection and tissue regulation and occurs in the gastrointestinal tract, mitochondria, skin, eyes, bone marrow, liver, and so on.
Melatonin Doesn't Start in the Evening
When we talk about melatonin, many people immediately think of sleep. But good melatonin regulation doesn't start in the evening—it starts in the morning.
Those who absorb natural daylight shortly after waking give their brain a clear signal: Now it's day. This clear light information stabilizes the internal clock and helps the body recognize the later evening as the opposite pole.
Exactly this way, melatonin can be released naturally and reliably in the evening. It's therefore important to recognize that nighttime regeneration works better the more natural light the body experiences during the day and the less artificial blue light it receives in the evening.
Many people feel unconsciously better in spring. More daylight and more time outdoors stabilizes our biological rhythm. The reward is significant improvement in sleep, energy, mood, concentration, digestion, and weight control.
Those who get too little natural light during the day and too much artificial light in the evening completely disrupt the natural sleep-wake mode. That's exactly why correct light hygiene is one of the most underestimated health factors. It's also accessible to everyone and costs nothing.
I don't consider melatonin supplementation useful for this reason. Absolutely recommended, however, is creating the conditions for melatonin to be synthesized in the body:
- More natural light during the day
- Darkness or red light in the evening
- Protection from artificial blue light both day and evening
"Being exposed to light at night can block melatonin production."
Source: NCCIH (NIH), Melatonin: What You Need To Know. https://www.nccih.nih.gov/health/melatonin-what-you-need-to-know
Melatonin at the Cellular Level: Three Important Protective Functions
Antioxidant Effect
Melatonin is the strongest antioxidant ever researched. It neutralizes free radicals and helps protect cells from oxidative stress. In the mitochondria—the "powerhouses" of our cells—it plays a particularly protective role and is therefore vital for every organ and tissue.
Regulation of Autophagy
Autophagy is a natural cell cleaning and renewal process. Damaged cell components are broken down and recycled. Melatonin is described in research as a regulator of this process, which is directly related to cell protection, aging processes, and regeneration.
Regulation of Apoptosis
Apoptosis refers to programmed cell death—a vital mechanism by which the body removes damaged or non-functional cells. Melatonin also acts as a regulator at the cellular level: In healthy cells, it has a protective effect, while in scientific contexts, such as with tumor cells, opposite effects have been demonstrated.
Melanin and Melatonin—What's the Difference?
Melanin and melatonin sound similar, but have very different roles in the body. Melanin is the pigment that colors skin, hair, and eyes and makes skin darker in response to sunlight.
It's considered the skin's natural protective pigment because it can absorb energetic radiation and reduce cellular damage. In a 2022 study of tree frogs from the Chernobyl zone, animals from historically more contaminated areas were classified with significantly darker coloring. Researchers described this as a possible evolutionary advantage of melanin-rich animals under high radiation exposure.
In everyday life, melanin's protective function shows in helping skin deal with light stimuli and prepare against some light-induced stress.
Melatonin, on the other hand, is a hormone that is mistakenly called a sleep hormone. It is released primarily at night and controls our sleep-wake rhythm, but it is synthesized during the day—and only when you have been exposed to sufficient daylight.
While melanin is associated with pigmentation, melatonin is primarily relevant for regeneration and an orderly circadian rhythm.
Vitamin D: When Sunlight Reaches the Skin
Sunlight is fascinating not just because it affects our internal clock. It also plays a central role in vitamin D production. The relevance of this hormone is well known and won't be described in detail in this article.
Figure 3: UVB radiation mainly acts on the skin surface and is central to the body's own vitamin D production
For the body to produce vitamin D itself, it needs UVB light and the right starting material in the skin: 7-dehydrocholesterol. This cholesterol-related precursor is first converted to previtamin D3 and then to vitamin D3 under UVB radiation.
"Vitamin D production in the skin under the influence of sunlight (UVB) is maximized at levels of sunlight exposure that do not burn the skin."
Source: Daniel D. Bikle, Vitamin D: Production, Metabolism, and Mechanism of Action, Endotext / NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK278935/
This topic is particularly interesting in spring, when we've gone many months without body-produced vitamin D from the sun.
In Germany, the sun is usually only high and intense enough from about April to September for the body to produce relevant amounts of vitamin D through the skin—especially around midday. Below about 30° sun elevation, vitamin D production is usually significantly reduced, while it becomes much more favorable at higher sun angles. In the winter months (October to March), UVB radiation in Germany usually isn't sufficient.
As a rule of thumb: if your shadow is bigger than you—no vitamin D synthesis is possible.
After the dark winter months, many people rightfully spend more time outdoors again. A conscious, gradual adaptation to solar radiation is exactly the way to prepare skin for the coming summer and for most, the long-awaited time by the ocean or lake. A loving approach to the sun is key, without excess.
Why the Right Approach to Sun Changes Everything
The right approach to sun exposure is, in my view, a decisive aspect. Not the fact that light reaches the skin, but how, when, for how long, and in what metabolic health condition we expose ourselves to the sun.
Gradual adaptation to sunlight is key. Skin needs time to adjust. Those who begin in spring to consciously and carefully integrate sun into their daily lives create entirely different conditions than someone who only spends many hours on the beach in summer.
A conscious approach to the sun means to me:
- Not excess, but moderation
- Not fear, but understanding
- Not avoidance, but preparation
The Sun Isn't the Problem. What's Going Wrong Today
Sunscreen and SPF Creams
From my perspective, one of the biggest problems lies not only in the product itself, but often in how it's used. Those who apply sunscreen and feel confident enough to spend many hours in the sun unprepared misjudge their own stress threshold.
Broad-spectrum sunscreen can help protect against UVA and UVB radiation, but has no effect on the rest of the light spectrum. Sunlight doesn't only consist of UVA and UVB rays.
We're therefore dealing with false and dangerous security: You "protect" yourself with sunscreen really only from a small part of sunlight—approximately 5%, namely UVA and UVB radiation alone—while overlooking that the remaining roughly 95% of the spectrum also acts biologically on our body.
So-called visible light (VIS), blue light (HEV), and infrared light reach deeper skin layers and can harm the body if exposed to the sun too long. This damage goes far beyond classic sunburn and initially remains unnoticed, which makes the potential consequences even more dangerous (e.g., skin cancer).
Figure 4: Sunscreen Doesn't Block All Light Reaching Deep Skin Layers
Sun protection should be seen as part of an overall concept of moderation, shade, clothing, nutrition, good natural skincare, and awareness.
The ingredients in many sunscreens also shouldn't be underestimated. Many were declared carcinogenic after decades and subsequently banned.
Nowadays, chemical UV filters are still viewed very critically due to their intolerance and hormonal burden, such as avobenzone, octocrylen, octinoxat, or oxybenzone.
Synthetic fragrances, consistency agents from mineral oil derivatives like silicones and film formers, as well as preservatives burden not only the skin, but the entire system, because at least 60% of what we apply to the skin enters our bloodstream. You can read more about this in our blog article "Toxin-Free."
Whether from the perspective of skin compatibility or environmental impact—it's undoubtedly wiser to approach sun exposure overall with moderation and deliberation, rather than wanting to close pores and completely block solar radiation.
Too little natural light during the day, too much artificial light in the evening, heavily processed foods, a sugar-rich diet, convenience meals, and the consumption of seed oils (rich in unsaturated omega-6 fatty acids) promote oxidation of your skin cells. Inflammation is pre-programmed, as is skin damage.
It can undoubtedly be said that as natural a lifestyle as possible creates the best conditions for skin and body to handle sunlight stably and healthily.
What My Personal Test Changed
Last year, I tried this slow, conscious adaptation to the sun for myself for the first time.
I previously often had spots and red patches, especially on my décolletage. Out of caution, I applied sunscreen very thoroughly to this area. First with conventional sunscreens, later—about two years ago—with mineral sunscreens based on titanium dioxide and zinc oxide.
Yet I never had the feeling that my skin there was really relaxed.
Last spring, I therefore consciously took a different approach. Starting in April, on sunny days I exposed myself to the sun for just a few minutes daily. Very consciously, without excess. I started with very short time windows and gradually increased the duration—roughly one minute longer each day. Always with attention to my skin's sensation, my energy, and the sun's intensity on each particular day.
My personal impression after this year-long test was very clear: My tan became much more even, I had more energy in summer, and on my décolletage, neither spots nor red patches nor swelling appeared.
Important were the right amount of sun, but also proper nutrition with plenty of antioxidants, healthy fats rich in omega-3, and using various techniques for conscious stress management and low cortisol levels.
I also covered up in summer after about an hour in the sun—with a linen skirt, a cotton blouse, and a hat—and then moved into the shade.
For me, this was a conscious return to a more natural approach to light. I prepared my skin well for the sun and afterwards cared for it as best as possible so it could regenerate.
Of course, every skin reacts differently, and my personal test isn't a universal rule for everyone. But it showed me how much difference a slow, conscious, and respectful approach to sunlight can make.
Conclusion: Use Sun Consciously Rather Than Fear It
The sun is a source of life, the most important biological regulator, and a natural stimulus deeply connected with our well-being, sleep, hormone balance, and skin health. If you'd like to learn more about high-quality sleep, you can find that in our blog article "Night Rest."
That's why we shouldn't fear the sun. Instead, we should learn the right way to interact with it again.
Practical Tips for Spring
- Wake at sunrise, open your window, and enjoy morning infrared light directly—regardless of whether it's cloudy or not.
- Use every opportunity for natural light outdoors during the day instead of spending the entire day exclusively indoors.
- Minimize artificial light and screen time in the evening so your body can continue producing melatonin undisturbed.
- Begin in spring with short, conscious sun exposures and increase gradually rather than overwhelming your skin on vacation. During this phase, always pay attention to your skin's sensation depending on intensity and time of day, and use shade, a hat, and light natural fibers like cotton or linen as a natural part of a smart sun approach.
Sources
📘 NCCIH (NIH) — Melatonin: What You Need To Know
📘 Blume C et al. — Effects of light on human circadian rhythms, sleep and mood — Nature and Science of Sleep, 2019
📘 Hoshino FM et al. — Physiological and Pathological Role of Circadian Hormones in Endocrine Systems — International Journal of Endocrinology, 2019
📘 Lambert GW et al. — Effect of sunlight and season on serotonin turnover in the brain — The Lancet, 2002
📘 Bikle DD — Vitamin D: Production, Metabolism, and Mechanism of Action — Endotext / NCBI Bookshelf
📘 Liu D et al. — Whole-body UVA irradiation lowers systemic blood pressure by release of nitric oxide from intracutaneous photolabile nitric oxide derivatives — Journal of Investigative Dermatology, 2014
📘 Mason IC et al. — Light exposure during sleep impairs cardiometabolic function — Proceedings of the National Academy of Sciences, 2022
📘 Latha MS et al. — Sunscreening Agents: A Review
📘 Autier P. — Sunscreen use and increased duration of intentional sun exposure: still a burning issue