Sun-Kissed

Why conscious sunbathing, light hygiene and a stable circadian rhythm matter so much

With spring, more daylight returns to our daily lives, and our bodies respond to the new light. The days grow longer, we feel more energetic, we want to get outside again and we instinctively crave sunshine on our skin.

This need is no coincidence. Natural light is far more than just brightness and warmth. It is a biological signal that influences our circadian rhythm, our sleep quality, our hormone regulation and also the body's own production of vitamin D. Sunlight is especially fascinating when it comes to the skin. It is not only our largest organ and our protective barrier against the outside world, but also the place where, under UVB light, the body's own vitamin D synthesis begins.

In recent years, there has been a lot of discussion about sun protection, UV radiation and skin ageing. In my view, one aspect often gets overlooked: a conscious, natural and measured approach to sunlight. By that I mean slowly getting your skin used to the sun, practising light hygiene and better understanding how closely the sun, the skin and inner balance are connected.
That is 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 the sun 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 source of energy and one of the most important timekeepers for our body. Humans have always depended on light – not only to see, but to function properly at their very core.

Natural sunlight supports numerous important processes in the body:

• It stabilises the circadian rhythm, which has a direct effect on 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, above all via the internal clock, the release of melatonin in the evening and the 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 linked 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 as soon as enough 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/

• By releasing nitric oxide from the skin, it can dilate the blood vessels and so support circulation.

  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 has an indirect positive effect on all metabolic processes. A stable light-dark
  rhythm is closely linked to 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 you take in enough natural light
  during the day and reduce artificial light 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 so much is being said about sun protection, well-ageing and potential risks, it's easy to forget that sunlight is something natural and vital. Not something we should fear across the board, but something we ought to understand better and use more consciously.

For me, then, the problem is not the light itself, but the wrong way of dealing with it. The sun is a natural stimulus, but a highly potent one. It consists not only of warmth, but of a complex light spectrum that interacts with our organism on many levels.

Figure 1: How deeply different parts of sunlight penetrate the skin

As the largest organ of our body, the skin receives these light stimuli directly. Depending on the type of light, it reacts differently to UVB, UVA and other components of
sunlight. That's exactly why it's so important not to label sunlight simply as "good" or "dangerous", but to take a more nuanced view.

Handling the sun the wrong way can show up directly in your skin – in the form of
overstimulation, a feeling of tightness, redness, an uneven complexion or premature wrinkles and skin ageing. This is mainly due to the well-known UVA radiation.

BUT! If someone hasn't done any sport for a whole year and suddenly
does squats with 200 kg and gets injured – who is to blame? The
weight plates? Hardly. It's exactly the same with the sun. It is not the
enemy – excess, a lack of preparation and a careless approach to its
power are.

Figure 2: UVA radiation penetrates deeper into the skin and is linked to light-induced skin ageing

At the same time, the skin is also exactly the place where light can trigger positive processes
– if we use it correctly. That's exactly why I don't believe in cultivating a fear of the sun, but in learning again how to handle it properly.

Why light is indispensable for our body

Our body follows an internal clock, the so-called circadian rhythm. This internal 24-hour cycle influences, among other things, when we feel awake and tired, how our hormones change over the course of the day and how well we regenerate at night. One of the most important external timekeepers for this internal clock is light. It helps the body to distinguish clearly between day and night.
The interplay between light and melatonin is particularly important here.

“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 is really above all a darkness hormone: it is released in response to darkness and signals to the body that the resting phase is beginning. Blue light after sunset, whether from artificial lighting or screens, can delay or even inhibit this release. That's why a good night's rest doesn't start when you go to bed, but with a healthy approach to light throughout the day.

The pineal gland is responsible for 5% of melatonin synthesis. The remaining 95% is synthesised locally outside the pineal gland in many tissues of the body – thanks to sunlight. This extrapineal production serves mainly to protect cells and regulate tissues, and takes place in the gastrointestinal tract, the mitochondria, the skin, the eyes, the bone marrow, the liver and elsewhere.

Melatonin doesn't just 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.
If you take in natural daylight shortly after getting up, you give your brain a clear signal: it's daytime now. This clear light information stabilises the internal clock and helps the body recognise the later evening as its counterpart.

This is precisely what allows melatonin to be released more naturally and reliably in the evening. So it's important to realise that night-time regeneration works all the better the more natural light the body has received during the day and the less artificial blue light it has been exposed to in the evening.

Many people unconsciously feel better in spring. More daylight and more time outdoors stabilise our biological rhythm. The reward is a clear improvement in sleep, energy, mood, concentration, digestion and weight control.

If, on the other hand, you get too little natural light during the day and too much artificial light in the evening, you throw your natural sleep-wake mode completely out of balance. That's exactly why proper light hygiene is one of the most underestimated health factors. What's more, it's accessible to everyone and free of charge.

For this reason, I don't think supplementing melatonin makes sense. What I absolutely recommend, though, is creating the conditions for your body to synthesise melatonin itself:

• More natural light during the day
• Darkness or red light in the evening
• Protection from artificial blue light both during the day and in the 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 cellular level: three important protective functions

Antioxidant effect

Melatonin is the most powerful antioxidant ever researched. It neutralises free radicals and so helps to protect cells from oxidative stress. In the mitochondria, the "power plants" 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 cleaning and renewal process within the cell, in which damaged cell components are broken down and recycled. You can find more on this in our article "Fasting". Research describes melatonin as a regulator of this process, which is directly linked to cell protection, ageing processes and regeneration.

Regulation of apoptosis

Apoptosis is programmed cell death – a vital mechanism the body uses to remove damaged or no longer functional cells in a targeted way. Here, too, melatonin has a regulating effect at cellular level: in healthy cells it has a protective effect, while in a scientific context, for example in tumour cells, the opposite effects have been demonstrated.

Melanin and melatonin – what's the difference?

Melanin and melatonin sound similar, but they have completely different jobs in the body. Melanin is the pigment that colours the skin, hair and eyes and makes the skin darker in response to sunlight.

It is considered the skin's natural protective pigment because it can help absorb high-energy radiation and so reduce cell damage. In a 2022 study of tree frogs from the Chornobyl zone, animals from historically more contaminated areas were found to be noticeably darker in colour. The 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 the way it helps the skin cope with light stimuli and arm itself against part of the light-induced stress.

Melatonin, on the other hand, is a hormone that is mistakenly called the sleep hormone. It is released mainly in darkness and controls our sleep-wake rhythm, but it is synthesised during the day – and only if you have been exposed to enough daylight.

So while melanin is related to pigmentation, melatonin is relevant above all for regeneration and a well-ordered circadian rhythm.

Vitamin D: when sunlight meets the skin

Sunlight isn't only so fascinating because it influences our internal clock. It
also plays a central role in the production of vitamin D. The importance of this
hormone is well known, so it won't be described in more detail in this article.

Figure 3: UVB radiation acts mainly at the skin's 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 substance in the skin: 7-dehydrocholesterol. Under UVB radiation, this cholesterol-related precursor
is first converted into previtamin D3 and then
into vitamin D3.

"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, after many months in which we have had to manage without
the body's own vitamin D production from the sun.
In Germany, the sun is usually only high and intense enough from around April to September
for the body to produce relevant amounts of vitamin D through the skin – especially around midday. Below a solar elevation of about 30°, vitamin D production is usually considerably
limited, while it becomes much more favourable when the sun is higher. In the
winter months (October to March), UVB radiation in Germany is generally
not sufficient.

As a rule of thumb: if your shadow is longer than you are —> no vitamin D synthesis is possible.

After the dark winter months, many people sensibly start spending
more time outdoors again. A conscious, gradual adaptation to solar radiation is exactly the way to prepare the skin for the coming summer and, for most of us, the long-awaited time by the sea or a lake. A loving approach to the sun, without excess, is the key.

Why the right approach to the sun changes everything

In my view, the right approach to the sun is a decisive factor. It's not the fact that light reaches the skin that matters, but how, when and for how long we expose ourselves to the sun, and in what state of metabolic health.

Slowly getting used to sunlight is the key. The skin needs time to adapt. If you start in spring to build the sun into your daily life consciously and in measured doses,
you create completely different conditions from someone who suddenly spends many hours on the beach in summer.

For me, a conscious approach to the sun therefore means:

• not excess, but moderation
• not fear, but understanding
• not avoidance, but preparation

The sun is not the problem. What's going wrong today

Sunblocks and SPF creams

In my view, one of the biggest problems often lies not only in the product itself, but in how it is used. If you put on sunscreen and then venture out unprepared into the sun for many hours, you misjudge your own limits.

Broad-spectrum sunscreen can help protect against UVA and UVB radiation, but it has no influence on the rest of the light spectrum. After all, sunlight doesn't consist only of UVA and UVB rays.

That's why we speak of a false and dangerous sense of security: with sunscreen, you are really only "protecting" yourself from a small part of sunlight – roughly 5%, namely UVA and UVB radiation alone – and overlooking the fact that the remaining 95% or so of the spectrum also has a biological effect on our body.

So-called visible light (VIS), blue light (HEV) and infrared light reach deeper layers of the skin and can harm the body if you are exposed to the sun for too long. This damage goes far beyond classic sunburn and initially goes unnoticed, which makes the possible consequences even more dangerous (e.g. skin cancer).

Figure 4: Even with sun protection, UV light is not the only light that reaches the deeper 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 of many sunscreens should not be underestimated either. In the past, many of them were declared carcinogenic after decades and subsequently banned.

Chemical UV filters such as avobenzone, octocrylene, octinoxate and oxybenzone are still viewed very critically today because of poor skin tolerance and their hormonal burden.

Synthetic fragrances, texturisers made from mineral oil derivatives such as silicones and film formers, and preservatives burden not only the skin but the whole system, because at least 60% of what we apply to our skin ends up in our bloodstream. You can read more about this in our blog article "Toxin-free".

Whether in terms of skin tolerance or environmental impact, it is undoubtedly wiser to approach sun exposure as a whole with moderation and care, rather than clogging your pores and trying to block solar radiation completely.

Too little natural light during the day, too much artificial light in the evening, highly processed foods, a high-sugar diet, ready meals and the consumption of seed oils (rich in unsaturated omega-6 fatty acids) promote the oxidation of your skin cells – inflammation is inevitable, and with it skin damage.

It's safe to say that living as naturally as possible creates the best conditions for your skin and body to handle sunlight in a stable and healthy way.

What my personal test changed

Last year, I tried this slow, conscious adaptation to the sun on myself for the very first time.

I used to have recurring blemishes and red patches, especially on my décolleté. To be careful, I always applied sunscreen particularly thoroughly in this area – first conventional sunscreens, later, around two years ago, mineral sunblocks based on titanium dioxide and zinc oxide.
Even so, I never felt that the skin there was truly relaxed.
So last spring I deliberately took a different path. From April onwards, on sunny days, I exposed myself to the sun for a few minutes every day. Very consciously, without overdoing it. I started with very short time slots and increased the duration step by step – roughly one minute longer each day. Always paying attention to how my skin felt, my energy and the intensity of the sun on that particular day.

My personal impression after this year-long test was very clear: my tan became noticeably more even, I had more energy in summer, and no blemishes, red patches or swelling appeared on my décolleté.

What mattered was the right amount of sun, but also a proper diet with plenty of antioxidants and healthy fats rich in omega-3, as well as using various techniques to consciously manage stress and keep cortisol levels low.
Even in summer, after about an hour in the sun, I covered up – 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 relationship with light. I prepared my skin well for the sun and then cared for it as well as I could afterwards so that it could regenerate.

Of course, every skin reacts differently, and my personal test is not a general rule for everyone. But it showed me how much difference a slow, conscious and respectful approach to sunlight can make.

Conclusion: use the sun consciously instead of fearing it

The sun is a source of life, our most important biological timekeeper and a natural stimulus that is deeply connected to our well-being, our sleep, our hormonal balance and the health of our skin. If you'd like to learn more about high-quality sleep, read our blog article "Night's Rest".

That's why we shouldn't fear the sun. Instead, we should learn again how to handle it properly.

Practical tips for spring

1. Get up at sunrise, open the window and enjoy the morning infrared light straight away – whether it's cloudy or not.
2. During the day, take every opportunity to get natural light outdoors instead of spending the whole day indoors.
3. Minimise artificial light and screen time in the evening so that your body can keep producing melatonin undisturbed.
4. Begin in spring with short, conscious periods in the sun and build up slowly, rather than suddenly overwhelming your skin on holiday. During this phase, always pay attention to how your skin feels, depending on intensity and time of day, and make shade, a hat and light natural fibres such as cotton or linen a natural part of a smart approach to the sun.

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


📘Burraco P, Orizaola G et al.
Ionizing radiation and melanism in Chornobyl tree frogs
Evolutionary Applications, 2022

📘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