Why Moderate Sun Exposure is Key to Your Health: The Surprising Benefits of Sunlight. And can it really cause cancer?

Rather than being something to be avoided, sunlight has many health benefits that most people are unaware of, from reducing chronic illnesses, to prolonging your life. Yes, our health is linked to the health of the planet, even the universe (sounds crazy, right!), and that we can't be healthy without being connected directly to nature and the universe, everyday. But it isn't always so simple! There is a complex relationship between sunlight and human health, arguing that its benefits far outweigh its risks. While concerns about skin cancer are significant, they are overshadowed by the broader, essential roles sunlight plays in regulating various aspects of health. Sunlight influences many biological processes, including Vitamin D synthesis, mood regulation, and circadian rhythms, which are crucial for overall well-being. The article suggests that the argument against sunlight, particularly due to UV radiation concerns, is less compelling when considering the full scope of its health benefits. It likens the impact of sunlight to other sources of energy in biological systems, such as oxygen, which also produce harmful byproducts but are nonetheless vital. In conclusion, avoiding sunlight is not advisable for optimal health or longevity. Instead, balanced sun exposure is recommended, as it supports numerous health functions while the body has mechanisms to mitigate the adverse effects of UV radiation. As research progresses, it is expected that the benefits of sunlight will be increasingly recognized as integral to a healthy lifestyle.

Light and Sunlight by Steven Lubka

I’ve been structuring my life around light cycles for the last 9 years. During that time I have come to believe it is likely the most significant variable in human health outcomes.

This may seem enormously counterintuitive to many, however, due to an abundance of evidence combined with the personal life-changing effects that embracing sunlight had on me, I’m convinced it’s true.

Like most other Americans, I grew up applying sunscreen anytime I went to the beach. The idea that the sun was healthy, or necessary, was never discussed. In my early twenties, I began to encounter individuals and research which claimed the exact opposite — that sunlight was essential to all-around, good health.

I also realized I had never experienced a true “dark phase”. Our entire culture was illuminated with artificial light. And yet, according to what I was learning, this abundance of artificial light was anything but beneficial for human health.

The research was persuasive, and I began to spend much more time outdoors and limit artificial light at night. The effects were nothing short of transformational.

The only way to truly explain it was as a massive increase in vitality itself. What do I mean by vitality? I mean a sense of energized vigorousness; a robustness to stressors; a passionate, focused drive. 

I am reminded of this simple truth when we go through several rainy weeks, or when I travel across the country for work. After a few days without the sun, deprived of the right light habits, I noticed a profound difference in myself.

When the light returns, the same vitality and drive is restored. I would imagine most people can understand a bit of this from the first day of spring, that moment when winter yields to the returning sun. A glorious day — one celebrated around the world via myriad festivals and religious rituals.

This essay will focus on the evidence and the science. Although I will make my argument in the language of empiricism (linking to peer reviewed studies, and the mechanisms of science), my personal experience of sunlight and what it has given me is far from the neutered, abstracted language of scientific journals. It is not improved blood work numbers or hormonal panels (although both are also true). It is a visceral and profound transformation in my lived experience. 

My goal with this essay is to once and for all answer a single question here: Does the cost-benefit analysis support having more sunlight in your life, or does it support avoiding sunlight?

I review many of the countless mechanisms by which sunlight acts on human health and address the concerns put forward by dermatologists and individuals who fear the effects of the sun’s UV radiation.

Why does Light even matter?

Let’s start by building a general framework for why light and Sunlight matter for human health. 

The average person thinks the answer is summed up by “Vitamin D”. However, the truth is far more nuanced. Light is one of the most bioactive substances in existence.

It is a nutrient and it is a drug. Both of these statements are literally, and empirically true.

Vitamin D can be thought of as a hormonal compound, however, even beyond  of this, light can also be understood as:

1. A critical input in biological timekeeping (circadian rhythm)

2. A key element in biophysics (various wavelengths have interactions with the body best thought of under the lens of physics)

3. Gene therapy (about half of your genes are modified by light) 

Some of these interactions we understand well — others not so well. Our true understanding of light’s impact on biology is still in its infancy, but there is a large body of robust work we can lean on presently.

I would personally estimate that non-Vitamin D-based benefits of light account for 80%+ of all its health benefits — this is far more than a Vitamin D story. 

(Also, many studies show supplementing Vitamin D does not in fact convey the same benefits as the endogenous production of Vitamin D via sunlight. More on this later.)

UV Radiation: Cancerous Toxin, Photo-Nutrient, or both?

I want to start by jumping into the most controversial part of the sunlight story. Is UV radiation going to give you skin cancer and cause your skin to look wrinkled and decrepit? Or, is it a beneficial and necessary “nutrient” that humans need for optimal health?

The real answer is both, but it depends on how, and even more importantly, in what context you are exposed to it.

The abstract from this paper in The Journal of Investigative Dermatology states it excellently:

“UVR is a skin carcinogen, yet no studies link sun exposure to increased all-cause mortality. Epidemiological studies from the United Kingdom and Sweden link sun exposure with reduced all-cause, cardiovascular, and cancer mortality. Vitamin D synthesis is dependent on UVB exposure. Individuals with higher serum levels of vitamin D are healthier in many ways, yet multiple trials of oral vitamin D supplementation show little benefit. Growing evidence shows that sunlight has health benefits through vitamin D-independent pathways, such as photomobilization of nitric oxide from cutaneous stores with a reduction in cardiovascular morbidity. Sunlight has important systemic health benefits as well as risks.”

UVR in isolation is proven to increase skin cancer rates. However, all studies of cumulative UV exposure (how much UV people get) show that people who get more UV radiation live longer, and experience less disease often by significant margins (including less cancer overall). Since no one gets isolated UV radiation in real life, this tends to suggest one should simply get more sun.

Sun exposure also provides significant benefits for cardiovascular health and diabetes.

Out of 100,000 people in a standard American population, 233.3  are expected to die from cardiovascular disease (CVD), 20.9 from diabetes, and 3 from skin cancer. Many more will live a less fulfilling and vibrant life due to diabetes and CVD as well, but not die from them.

High amounts of sunlight exposure have also been shown to reduce cancer rates of countless other cancers, such as cancer of the pancreas, colon, stomach, brain, and more.

When you add up the overall risks of all of these diseases and compare them to skin cancer, it’s not even close. The total burden of disease that sunlight alleviates is an order of magnitude worse than those it causes. Studies have continually shown this relationship.

“In the Melanoma in Southern Sweden study, 30,000 Swedish women were followed for 25 years, with sun-seeking behavior and relevant confounders recorded at baseline. Twenty-five years after enrolment, sun-seeking behavior was inversely correlated with all-cause mortality, despite a higher incidence of cases of melanoma in those with more sun exposure (Lindqvist et al, 2014). The reduction in all-cause mortality was particularly related to lower rates of cardiovascular death (Lindqvist et al, 2016).” 

This means that after twenty-five years, these 30,000 women lived longer the more sun they got despite higher rates of skin cancer. It’s worth noting that it is rare to find a study following this many people for this long! 

A much larger UK Biobank study followed 377,000 white-skinned Europeans and monitored their sun habits and the latitudes at which they lived. They also studied the use of tanning beds (which I do not recommend).

For all methods and relationships, they too found the more sunlight or UV exposure these white-skinned Europeans had (this detail is important), the longer they lived. Additionally, every 18 miles further south they lived added about 16 days to their average life expectancy. 

You read that right, fair-skinned Europeans lived longer in Egypt than in their ancestral environments. As I was researching this essay, this result surprised even me! While these individuals are clearly more vulnerable to sun damage than native Egyptians, being in a higher UV environment was nevertheless health- promoting.

Why did these individuals live longer? Reduced mortality from cardiovascular disease, cancer, AND skin cancer. How is this possible? Generally, the trend appears to be that people with higher UV exposure are more likely to get skin cancer but less likely to die from it.

Let’s be clear, light-skinned individuals are more vulnerable to UV damage. The average light-skinned redhead may not want to bake in the Egyptian sun for 4 hours. Yet, within reason, more UV exposure from the sun continues to be associated with a longer life and less disease.

While increased UV exposure does result in more skin cancer (but less skin cancer death), what about all of the seemingly conclusive research on skin cancer? Should it be taken at face value? I believe there is a good reason why it should not. Skin cancer studies generally take two forms: isolated cell cultures and population-based studies.

Isolated cell studies have limited generalizability due to the fact that humans are not merely a clump of cells, and sunlight is not isolated UV light — it is a whole spectrum. Red light, for example, has been shown to mitigate UV damage when applied to the skin prior to UV. 

We need more whole-spectrum studies on cell cultures to get better data, but even these would obviously be limited, as the human body has many mechanisms that mitigate UV damage. The whole human system is robust, with myriad mechanisms to adapt to stressors. Hormesis, an adaptive response to stress, is the rule of human biology. 

While exploring the effect on cells of UV in isolation can certainly provide valuable insights, it would be foolish to blindly extend those findings to human biology. Scientists even struggle to replicate research done on mice to humans, let alone clumps of cells!

Population-based studies are limited for a different reason — the subjects do not exist in the isolation of a laboratory, but out in the dynamic, unpredictable, real world.  In that environment, your habits influence how much damage you will receive from UV. Additionally, these population-based studies stop short by merely showing that a given population has a higher rate of skin cancer. However, individuals who get more sunlight have a much higher chance of surviving skin cancer, and individuals in the lowest sunlight exposure groups have a much higher chance of dying from skin cancer. Few papers tackle this whole picture!

The Circadian Cycle

The human body operates on a circadian cycle — it has a daytime phase and a nighttime phase. Properly aligned, this cycle is conservative and protective of DNA during the daytime, where UV is high, while during the dark phase, it focuses on the repair of DNA. DNA is more vulnerable to damage during the repair phase.

If someone’s circadian clock is out of alignment DNA may be getting UV exposure during the repair phase.

Early morning sunlight exposure makes you less likely to burn, and you suffer less damage from the UV. Light receptors in the eyes signal to your skin the presence of intense light and allow the skin to protect itself from the negative effects of UV. What if you are wearing sunglasses, though? If you wear sunglasses you deny your body this signal to the skin from the eyes, and potentially increase your risk of skin damage.

This is a huge reason to avoid sunglasses unless driving or operating heavy machinery. There are some diseases of the eye that may warrant sun protection, but eye health itself is also deeply supported by sunlight. 

Consistency in sun exposure crucially influences cancer rates. Studies show that inconsistent sun exposure, like working indoors all week and then getting intense sunlight on weekends, increases the risk of melanoma. In contrast, regular and consistent sun exposure decreases the risk of melanoma. This aligns with the biological concept of hormesis, where moderate, consistent exposure to stressors strengthens the body’s adaptive responses.

Skin cancer studies do not adjust for chronic vs intermittent exposure when looking at broad populations. Consider, for example, a study on Australian Surfers. How many people in Australia work indoors 40 hours per week, under artificial light, with misaligned circadian clocks and then go to the beach on the weekend?

These individuals are at greatest risk for UV damage, and they most likely compose the bulk of such a population-based sunlight-induced study. Now, does this mean that UV exposure isn’t a skin cancer risk? Not inherently. It very well might be. However,  it almost certainly is *less* of a risk than such studies show.

I am not here to wave my hands and say there is literally nothing to worry about. I am here to say we live in the real world, and even if the risks were as bad as the worst studies say (which it almost certainly isn’t) the research continually shows that the people who get the most sunlight are much less likely to die from any factor than people who get the least sunlight. The disease burden that is mitigated by high sunlight exposure is an order of magnitude or more than the risk the population faces from rising skin cancer rates.

There are many studies I could cite which dispute the melanoma and sunlight relationship (here, here, here, here, here, here, here). Sunburns are specifically related to melanoma, but many researchers dispute that non-burning sun exposure is related to melanoma risks. In fact, many would argue consistent non-burning exposure is protective against melanoma.

I am not discussing those studies here because, even without disputing melanoma results, I believe that the case for sunlight is overwhelming.

However, one could make a solid argument that melanoma is materially less sunlight induced than most people think. Melanoma rates have risen rapidly even while humans avoid the sun more than ever, and many studies show that office workers are at particular risk for melanoma (one theory is UV-A via windows without Vitamin D being produced in the skin itself makes these individuals particularly vulnerable).

Circadian Rhythms and Life on Earth 

A huge part of the sunlight story is that our biology relies deeply on circadian rhythms to do everything from managing hormones to metabolizing fat. 

To set this story in its proper context, let’s explore the story of Melatonin. Most people know of Melatonin as a compound that helps humans fall asleep. The real story of Melatonin is far more interesting.

Melatonin first emerged 3.2 billion years ago and has existed since without any alterations across almost all life on Earth. It is believed to exist in most or all animal and plant life. 

How important and central could such a compound be to be shared by almost all life and survive 3.2 billion years in an unaltered state?

Most Melatonin is produced within mitochondria as the most potent antioxidant known to man, far surpassing anything from food. Mitochondria produce more Melatonin when Infrared Light penetrates the body and strikes the mitochondria directly. The brain also produces melatonin which is involved in sleep, and suppressed by artificial light at night.

Countless plants and animals have circadian rhythms. A huge portion of all human genes have circadian factors. One must ask why so much life relies on a light-dark cycle and how central this suggests circadian biology is to life on Earth.

I personally believe this is because sunlight is the most widely accessible source of energy in nature, and everything has evolved to take advantage of the free solar energy we receive every day. In the next section, we will explore how UV light is literally a usable form of biological energy, just like food, but also how this energy comes with a cost.

My belief is that circadian rhythms emerged to utilize this free energy as much as possible, and then to mitigate the downsides during the dark phase. Obviously, the reality is much more complicated than this and defies such a simple explanation, yet this may be a functional model to start to think about why circadian health matters so much.

Circadian biology manages both glucose and fat metabolism. It is also central to bone health and preventing osteoporosis. Furthermore, circadian disruption is intimately linked to mental health disorders ranging from depression to schizophrenia.

Circadian rhythms govern the activation and inactivation of countless genes governing immune function, metabolism, and homeostasis. Diabetes is increasingly being understood as a circadian illness. 

Hundreds of pages could be filled with all of the circadian system’s biological impacts and all of the health effects it has. For now, merely keep in mind that circadian processes touch most biological processes, and light is the primary way your body manages its circadian processes.

UV Mechanisms and Benefits

Beyond Vitamin D, which we will explore later, UV light has specific health benefits and mechanisms which are, to put it lightly, fascinating. 

The human body possesses the ability to perform the transduction (converting one form of energy into another) of UV electromagnetic energy (these are high-energy wavelengths) into chemical, hormonal, and neural signals!  

It’s worth exploring the physics of this for a moment. The energy of UV is comparable to the energy of covalent bonds (these are the electromagnetic bonds that hold atoms together within a molecule). This means that any electron excitement by UV is enough to generate or break a covalent bond. This means that in a biological system it can supply necessary energy for countless processes, and some scholars believe it may even have played a critical role in the development and evolution of life itself.

A simple example is the production of Vitamin D (which is actually many different compounds and a multistage process) which requires UV-B-induced carbon bond cleavage to initiate. 

If this description made your eyes glaze over, let me state it more simply.

The sun literally donates energy to biology — including human biology. It is a source of usable energy.

Looking at the role of UV radiation in biology, the portrait increasingly becomes one of energy. In biology, the production and usage of energy is both necessary and constructive yet it also bears costs and damages. In this way, it is similar to oxygen. You both need oxygen to live, and it is slowly killing you.

UV donates tremendous biological energy to the organism, which is used in productive and health-promoting ways. Yet, this very process has certain costs, which the organism must repair and balance post-exposure.

Your body, fortunately, has countless well-defined mechanisms to counteract the negative effects while optimizing the positive. 

When UV radiation strikes your skin, the skin functions as a neuroendocrine organ. This means UV is a critical component of your neurological system and your hormonal system.

The skin, in response to UV, produces steroids, thyroid hormones, endocannabinoids, POMC, oxytocin, melatonin, growth hormone, and countless other compounds. All of these interactions occur in addition to Vitamin D pathways.

UV-B is also absorbed and utilized via the eyes, not just the skin, and plays a key role in the global homeostasis of the body. Exposure of the eye to UV radiation modulates pituitary function and has distinct impacts on internal organs and skin. One fascinating example is the exposure of the eyes to UV-A mitigated cancer of the colon.

UV-B activates the opioidergic system, producing natural endogenous opioid effects, and this has been shown to be effective at improving addiction outcomes.

UV radiation activates nitric oxide pathways which lower blood pressure, and reduce cardiovascular disease. This is one of the largest ways increased UV exposure reduces mortality.

The UV radiation spectrum is one of the most bioactive parts of the light spectrum and far from being seen merely as a carcinogen, it should instead be seen as necessary for health and even fundamental in the development of biology itself.

Like any source of energy, UV has costs and benefits. But much like how digesting food and inhaling oxygen actually deteriorates your body, you would never actually want to go without these things. 

Harnessing energy always comes with costs, but the goal of biology is to do this very thing as well as possible.

Vitamin D

Vitamin D is the one benefit of sunlight everyone is aware of. As such there is a lot written on its benefits. It is a hormone that is positively associated with many beneficial health outcomes. 

However, this is because it often functions as a proxy for sun exposure. Most research doesn’t adequately distinguish between the effects of sunlight via non-vitamin D pathways and via Vitamin D itself.

In this section, I will spend more time exploring what you don’t know about Vitamin D, rather than reiterating the benefits which are plastered all over the internet.

Vitamin D became popular when it was discovered that cod liver oil, which contained vitamin D, was able to prevent rickets. From this moment onward, everyone assumed the dietary compound and the process induced via sunlight exposure were largely synonymous. 

However, much research on this topic is confounded by the fact that most people’s Vitamin D levels are a representation of their sunlight exposure. How many health influencers and doctors have promoted Vitamin D supplements as an easy solution? What if they are all, mostly, wrong? 

The two largest randomized studies of Vitamin D supplementation, the Vital Study, with 25,000 participants, and the ViDa study, with 5,000 participants, both demonstrated no benefit from Vitamin D supplementation on cardiovascular disease, cancer incidence, or many other endpoints.

The New England Journal of Medicine in 2022 concluded that the general population should stop taking Vitamin D supplements. The bulk of data shows that supplementing Vitamin D is not beneficial, and may be actively detrimental. 

Vitamin D’s pristine reputation comes from correlation studies that find higher vitamin D levels associated with better health outcomes, yet a reasonable observer must conclude this is because it is sunlight that is actually beneficial.

Nitric Oxide and Cardiovascular Outcomes

Studies have shown that people living in higher UV areas have lower blood pressure. Other studies have shown that individuals who try to limit sun exposure have higher blood pressure and are more prone to hypertension. 

Sunlight has been shown to reduce blood pressure by about 10% after 30 minutes of exposure. However, these results didn’t persist all day. This immediate response is likely due to Nitric Oxide release.

Yet, even though this immediate drop reversed itself, sunlight habits are positively associated with lower blood pressure, better cardiovascular outcomes, and less stroke and heart disease.

Sunlight and Genes

Up to 20% of genes in mammals are circadian coded, they function differently at different points in our circadian cycle. Moreover, up to 50% of all protein-encoding genes show circadian-dependent transcription.

Despite being on the inside of your body, your cells and genes have light receptors and respond to light. Light, which does penetrate your skin and is also produced internally in intercellular communication.

Scientists at MIT used a new light device to manually turn genes on and off. The sun does the same thing when you are in it.

Genes also show seasonal variations. For example, in the winter, pro-inflammatory genes get increased to prepare the body for infection at the expense of cardiometabolic health.

However, when people live indoors they are sending their body a signal that it is winter all year round. Perhaps these genetic components explain why sunlight improves our cardiovascular systems’ health!

Myopia and Sunlight 

Myopia, or nearsightedness, is rising rapidly globally, affecting 80%- 90% of East Asian children.

Sunlight and time outdoors is strongly associated with preventing nearsightedness and eye-related issues. Myopia is also associated with doing work where you are looking at something close to your face for long hours.

However, new research shows that sunlight is a much stronger predictor of avoiding nearsightedness than near work. 

The American Academy of Ophthalmologists and the International Task for Myopia now recommend children spend 8-15 hours outdoors per week.

Multiple Sclerosis, Type 2 Diabetes

MS is a disease whose rate of incidence increases the further north you get from the equator. The effect is material and robust. Equatorial regions have massively lower rates of MS than northern latitudes. Vitamin D supplementation does nothing to prevent MS.

Type 2 Diabetes (T2D) is increasingly being understood as a circadian illness. Higher vitamin D levels have been shown to be robustly related to a lower chance of developing T2D while Vitamin D supplementation does not provide the same benefit.

T2D is also linked to disruptions in circadian rhythms and processes. Even organizations as institutionally well-known as the Mayo Clinic are now discussing the relationship between T2D and light. 

The body’s insulin response to food is highly influenced by the light environment. Bright light at night increases the body’s insulin response when one consumes food.

People who lived in areas with the highest levels of outdoor artificial light had a 28% higher chance of diabetes. Human biology is circadian biology.

All-Cause Mortality and Cancer

Lack of sun exposure has been estimated to be responsible for up to 340,000 excess deaths per year in America and 480,000 deaths per year in Europe along with increased risks of countless diseases.

One study estimated that 12.8% of all deaths in the US could be attributed to avoidance of the sun. Whereas another study demonstrated that avoidance of the sun is a risk factor of the same magnitude as smoking.

Researchers found individuals in the lowest segment of Vitamin D levels had a 400% increased risk of breast cancer compared to individuals in the highest segment. While others found that among individuals with breast cancer, those in the highest segment of Vitamin D levels had a 79% reduced chance of dying from the cancer. 

However, keep in mind it is not Vitamin D levels that are the causal variable here, as Mendelian randomization analysis has shown. Vitamin D levels just serve as a representation of how much sun exposure the individual got. 

Humans had a 104% higher risk of colorectal cancer with the lowest sun exposure habits.

Similar results have been shown for many other types of cancer. Higher sunlight exposure dramatically reduces your chances of getting cancer and improves your chances of surviving cancer.

Neurological Conditions

Sunlight avoidance resulted in an increased risk of both Alzheimer’s and Dementia by 125% and 122% respectively.

Sunlight avoidance by mothers resulted in a 142% increased risk of Autism in their children. 

Infrared Light and Red Light 

Infrared light is another bright spot for the benefits of sunlight and red light. Red and infrared therapy have become very popular via medical devices for skin health, recovery, and even for neurological treatment via lasers. 

Infrared is unique in that it penetrates deeply into tissue and actively reaches the inside of cells and organs. It acts on a photoreceptor called cytochrome C and participates in the electron transport chain, a foundational component in the production of energy on a cellular level.

Once cytochrome C is activated by infrared light, electron transport is accelerated and ATP is produced at an increased rate.

This story gets even more interesting. The mitochondria, which produce energy for the body, do so via a literal rotator motor inside the cell. This motor is the subject of much fascination, but the relevant part is that it sits within water.

It was assumed this water functioned similarly to bulk water, but in fact, there is interfascial water (the surface layer of water attracts the liquid, creating additional friction) which increases the viscosity of water within the cell.

When the water within the mitochondria reaches a higher level of viscosity the energy production of the cell is impaired.

Infrared light penetrates the body, enters the cell and the water in the cell, and reduces the viscosity of this water, increasing ATP production. 

In other words, sunlight makes mitochondria go brrrrrr (the technical term). Increased ATP production at the mitochondrial level supplies the entire body with more energy, for all processes from top to bottom.

Photobiomodulation 

Building on this mechanism of Infrared and near-infrared light to penetrate the body and produce cellular and mitochondrial benefits is the field of photobiomodulation.

Photobiomodulation is the process of shining medical-grade lasers on parts of the body to produce local and systemic outcomes.

Photobiomodulation has been shown to affect 7 major categories of disease: neuropsychiatric diseases, neurodegenerative diseases, ischemia, nerve injury, pain, paresis, and neuropathy.

Interestingly, it has been shown to also treat depression and anxiety. It has even been used to treat the neurological impacts of COVID more recently.

What is particularly compelling is the apparent ability of photobiomodulation to produce local outcomes, meaning it specifically improves the tissues and organs it shines infrared radiation on. This may suggest we are on the way to inventing a targeted light therapy paradigm.

Mental Health 

Circadian Rhythm disruptions have been found to impact everything from depression and anxiety to autism, ADHD, BPD, Bipolar disorder, and schizophrenia.

Light is critical to mental health. 

This goes beyond simply disease pathologies and extends to otherwise healthy people who experience better mental health, motivation, and focus with increased sunlight exposure.

Viewing morning sunlight can increase dopamine, epinephrine, and serotonin in huge amounts.

Mental health is in many ways, a derivative of your light environment. They are intimately linked.

If you do not believe this and wish to verify it for yourself, go sit in a dark room for 72 hours and see what your mental health is like.

Sunscreen and Sunglasses

Many people have questions about sunscreen and sunglasses. Obviously, individual recommendations vary, some people may have family members who died of skin cancer. Some people have light skin and some have dark. All of these factors must be considered to truly arrive at personal recommendations, which I cannot make here.

That being said, here is a broad way to think about it.

1. Many commercial sunscreens have been shown to be toxic, these should be avoided in all circumstances 

2. Zinc and Titanium Oxide sunscreens appear to be consistently safe. Any sunscreen usage should be Zinc or Titanium

3. Getting a sunburn is more harmful than wearing sunscreen. If you are in a situation where you will be forced to burn, use sunscreen!

4. However, while sunscreen can protect you from a burn it will also negate and alter many of the mechanisms of sunlight. You will not produce much Vitamin D and the light spectrum will be altered 

5. There are many currently unknown interactions of sunlight, the various compounds in sunscreens, and the skin barrier. 

However, most people with good circadian habits and consistent sun exposure will generally adapt to their environment. Consistent non-burning sun exposure is the gold standard. It is easy to simply go under shade if you have gotten too much sun. For most cases, the easiest way to manage sun exposure is simply gradual adaptation.

What about sunglasses? Sunglasses have even less place in the average person’s habits. Barring severe eye conditions or edge cases, the only reason people feel like they need sunglasses is a lack of adaptation (or they are on the water).

One should obviously wear sunglasses as needed while driving or operating machinery. You aren’t getting benefits behind the windshield anyway.

However, the eye detecting all wavelengths of light (including UV) is an incredibly important part of the health benefits of sunlight. You want your eyes to see daylight. Do not stare at the sun however….

Please note, contact lenses and glasses are not neutral. I highly recommend wearing glasses instead of contacts as light can still get around the glasses from the top and aides. I am substantially distrustful of contact lenses, but there is little research here.

Even clear glass alters the wavelengths of light you are receiving from the sun, and it blocks UV-B entirely. So what should you do if you have very poor vision?

I would recommend a practical middle ground. It is imperative you see early morning light directly via the eye with no medium in between. At sunrise take your glasses off and sit in a chair and watch the sunrise for 30 minutes. For the rest of the day, you can wear your glasses.

Specific wavelengths and spectrums are more central during the early morning wake cycle, whereas general brightness is more critical during midday which glasses will not alter.

A Practical Guide to Getting These Benefits Yourself

What should you actually do if you want to get these benefits? It’s actually fairly simple.

Let’s be clear, obviously simply living 100% outdoors with no artificial light is “optimal”, but you can get most of the benefits with a few simple steps. Benefits increase past these, but I’m going to share the bare minimum.

I get it, people have whole lives and responsibilities! Not everyone gets to work for a company like mine!

That being said, if you are serious about this, get a remote job and build an outdoor workspace.

Circadian protocol:

1. Wake up with the sun or close to sunrise

2. Immediately go outside and see the sun directly on your eyes (no contacts or glasses). Do not stare at it, just see the light. Do this for at least 25 minutes. Getting light in the eyes is the crucial part but on the skin is beneficial too

3. Take sun breaks throughout the day. At Least 3-4 15-minute outside slots during your workday. It’s important to get non-burning skin exposure at this time for Vitamin D

4. After work, spend some time outside and later view the sunset 

5. Within one hour of sunset switch all lights and screens in your home to red. You can get color-changing lightbulbs online inexpensively and all devices have apps that manage color filters now. I recommend f.lux and twilight.

Now, I personally get substantially more sun than this and spend hours each day outside. You will certainly get more benefits doing this, but I share this as a starting point for the average person.

As you start to feel the difference, you will naturally want to do a bit more than these recommendations above. Just make sure to avoid sunburns at all times. 

Conclusion 

I hope this exploration of the myriad and varied impacts of sunlight on human health has helped set the stage for a fuller understanding of the health questions surrounding sunlight.

Avoiding or embracing sunlight is not a minor question, nor only dermatologists, nor something that can be satisfied with Vitamin D supplementation.

It is a profoundly deep question that is pivotal to most aspects of human health and likely implicated in the origin of biological life itself.

This is not a comprehensive summary of the research nor even all of the areas sunlight impacts. Our current knowledge is incomplete in many ways.

However, this should be sufficient for the reasonable reader to answer one question, and one question alone:

Do the risks and rewards skew in favor of more sunlight in one’s life or should one avoid the sun for optimal health and a long life?

The dermatological argument and the skin cancer argument pales in comparison (pun intended) to the dominant and critical role sunlight plays in regulating almost every element of human health. The dermatological argument is weak and flimsy when situated properly in a robust cost-benefit analysis. It only appears persuasive when rhetorically isolated and allowed to focus solely on skin cancers. 

It is worth noting that each section in the article above represents only the tip of the iceberg, and a reasonable reader should conclude there are many more mechanisms to be discovered and evaluated.

The conclusion, one should walk away with is that sunlight touches every aspect of human health, and saying we should avoid it is like saying we should avoid movement or food. While exercising you may sustain an injury, and yet no doctor would say we should avoid exercise for this reason.

I will leave you with a conclusion restated, for the argument against sunlight hinges on this eternal UV radiation boogie-manning. It increasingly looks like UV radiation is simply another biologically accessible form of energy organisms use. It is similar to oxygen or food.

When we breathe oxygen it produces free radicals which are detrimental to our health. When we use energy in the human system we also produce detrimental outcomes. The production and use of energy in systems produce entropic byproducts. This is as true in engines burning fossil fuels as it is true in biology. 

UV radiation shares many similarities with these other systems. It donates energy directly to biology which is usable in many key processes. The same is true for infrared light and other spectrums.

This energy is essential and critical to numerous processes in human health. It also produces negative byproducts.

Humans have countless systems to mitigate these byproducts, just like the free radicals produced by oxygen metabolism. In fact, sunlight avoidance actually impairs our ability to repair UV damage — imagine that!

I do not believe there is any review or interpretation of the literature that should lead someone to conclude avoiding sunlight or even avoiding UV radiation is optimal for health — lifespan or healthspan.

As our understanding of the biological impacts of light continues to deepen I believe the evidence will only increasingly lean towards sun exposure being seen as healthy and necessary in an overall wellness regimen.