A large number of public health messages over the past century have focused on the dangers of too much sun exposure, such as aging, skin cancer and DNA damage. However, in reality, today’s science tells us that exposure to the ultraviolet radiation (UVR) in sunlight has many beneficial effects on human health.

Indeed, most people are aware of the impact of sun exposure on Vitamin D production, which is a very important factor. However, there is a host of other health benefits that have been overlooked in the debate over how much sun is necessary for optimal health. This article will dive into the science to uncover the various ways in which sun exposure, at the right times and intensities, is a vital component of good health.

Sunny day

Introduction

Planet Earth has been bathing in sunlight for more than 3 billion years (R).

As life forms evolved in the ocean they were exposed to sunlight. Eventually, early life learned to make carbohydrates using sunlight as their energy source (R).

Given the importance of sunlight for life on this planet, it makes sense that all lifeforms, including humans, have evolved to use the power of the sun to their advantage (R).

Humans have a long history of using sunlight therapy that dates back to the ancient Greeks. Today, sunlight therapy is referred to as heliotherapy.

We instinctively think people with a tan look healthier. A tan is simply the body’s way of protecting itself from the power of the sun’s rays (R).

Hopefully, after reading the following benefits of sun exposure, you will start to appreciate the powerful effect that the sun can have on your health.

It’s important to note, that whenever a study shows an association with low vitamin D, all we really know from that is that people aren’t getting enough sun.  Vitamin D is a good measure of sun exposure on your body.

Circulating vitamin D levels provide a surrogate measure of sun exposure and that it is the other molecules and pathways induced by sun exposure, rather than vitamin D-driven processes, that explain many of the benefits often attributed to vitamin D (R).

Therefore, if you take vitamin D, you won’t prevent many of the risks associated with lower vitamin D.  The safest way to prevent these risks is to actually get sun.

Sun Exposure Decreases Risk of Dying

In southern Sweden, there was a 2X increased risk of dying among those who avoided sun exposure compared with the highest sun exposure group (R).

Nonsmokers who avoided sun exposure had a life expectancy similar to smokers in the highest sun exposure group, indicating that avoidance of sun exposure is a risk factor for death of a similar magnitude as smoking. Compared to the highest sun exposure group, life expectancy of avoiders of sun exposure was reduced by 0.6-2.1 years (R).

Top Health Benefits of Sun Exposure

1) Sunlight Increases Vitamin D Levels

The best-known benefit of sunlight is its ability to boost the body’s vitamin D supply (R).

Vitamin D is synthesized in the skin through a photosynthetic reaction triggered by exposure to UVB radiation (R).

Most cases of vitamin D deficiency are due to lack of outdoor sun exposure (R).

At least 1,000 different genes, governing virtually every tissue in the body, are regulated by the active form of the vitamin D (R).

Vitamin D accumulates in cells of the intestines, where it enhances calcium and phosphorus absorption, controlling the flow of calcium into and out of bones. Thus, adequate vitamin D production through sun exposure is vital for healthy bones (R).

Without enough vitamin D, bones will not form properly. In children, this deficiency is called rickets, a disease that retards growth and causes skeletal deformities, such as bowed legs (R).

Sunbathing has been recommended for centuries as an effective treatment for rickets (R).

Low vitamin D levels cause and worsen osteoporosis and osteomalacia (painful bone disease) in both men and women (R).

As if this weren’t compelling enough, a recent study showed that low vitamin D levels from sun avoidance increase all-cause mortality (R).

1.1) Ideal Vitamin D levels

  • At risk of Vitamin D deficiency: Serum 25OHD less than 30 nmol/L (12 ng/mL) (R).
  • At risk of Vitamin D inadequacy: Serum 25OHD 30–49 nmol/L (12–19 ng/mL) (R).
  • Sufficient in Vitamin D: Serum 25OHD 50–125 nmol/L (20–50 ng/mL) (R).
  • Possibly too Much Vitamin D: Serum 25OHD greater than 125 nmol/L (50 ng/mL) (R).

2) Sun Exposure Sets Circadian Rhythm (Important!)

Studies published in the 70’s showed that part of the brain (the hypothalamus), the suprachiasmatic nucleus (SCN), functions as the core circadian pacemaker in mammals. Basically, the SCN helps your body tell the time of day (R ,R2, R3).

The SCN receives its messages from the eye. These messages will depend on how much light the eye is being exposed to (R, R2).

So, your body’s key way of telling the time of day will depend on how much light your eyes receive at certain times of the day.

This is very important for your health. Studies show that having a good circadian rhythm is important for regulation of sleep-wake cycles, hormone release, body temperature and other important bodily functions (R).

Getting enough sunlight during the daytime is essential for good sleep. Getting enough light increases night-time melatonin levels (R). You might also find you go to bed earlier (R).

Humans are most sensitive to light stimuli during the night. As a result, just as important for entraining your circadian rhythm as getting sunlight in the morning is avoiding artificial light at night (R).

This is why I use blue blocking glasses after sunset. These Swanick glasses are better for social settings.

3) Sun Exposure May Protect Against Cancer

Although skin cancer has been associated with too much UVR exposure, especially in areas of the world with a damaged ozone layer, a number of other cancers could result from too little sun (R).

For example, those who live in places with less sun (e.g high latitudes) are at higher risk of dying from breast, ovarian, colon, pancreatic, prostate, and other cancers (R).

One study investigated the impact that vitamin D supplementation has on cancer rates. Results showered that taking 2–4 times the daily recommended intake of vitamin D3 (200–600 IU) and calcium resulted in a 50–77% reduction in expected cancer rates (R).

Ironically, high sun exposure increases survival rates in patients with early-stage melanoma (R).

Similarly, occupational exposure to sunlight lowers risk of skin cancers (R).

Most skin cancers occur on parts of the body that are covered by clothes (R).

4) Sun Exposure Can Protect Against Heart Disease and Lower Blood Pressure

Vitamin D deficiency links to cardiovascular disease can be found in a number of studies demonstrating a 30% to 50% higher cardiovascular morbidity and mortality associated with reduced sun exposure caused by changes in season or latitude (R).

Conversely, the lowest rates of heart disease are found in the sun-drenched Mediterranean coast and in southern versus northern European countries. Cardiac death has been reported to be the highest during winter months (R).

A number of studies have attempted to correlate vitamin D3 with cardiovascular events. Heart attack patients had lower mean D3 concentrations than control subjects.  There was a 57% reduced risk for those above compared with those below the median of D3 (R).

Rates of high blood pressure correlate with latitude (i.e. less near equator) and generally rise in winter (R).

One study exposed a group of high blood pressured adults to a full spectrum tanning bed. After three months, participants had an average 180% increase in their Vitamin D levels. They also had an average 6 mm Hg decrease in their systolic and diastolic blood pressures. (R)

The blood pressure-lowering effect of sunlight might be due to its ability to increase nitric oxide in the body (R, R2).

Active D/Calcitriol normalizes the impaired heart contractility observed in experimental vitamin D deficiency (R).

Calcitriol regulates heart muscle production, and prevents thrombus formation and cell adhesion (R).

Calcitriol is known to suppress the synthesis and secretion of atrial natriuretic peptide and increases matrix Gla protein, a protein that protects against arterial calcification (R).

Having lower vitamin D increases PTH, which has many detrimental effects on the heart (R).

There are many mechanisms by which low calcitriol and high PTH harm your heart (R).

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5) Sun Exposure Makes You Happier and Combats Depression and SAD

The 3 main mechanisms by which sun benefits mood is by the serotonin and dopamine system and vitamin D.

Sun and Serotonin

One study found that sun exposure increases levels of serotonin and its associated receptors in the brains of healthy men. This is important as relatively high serotonin levels result in better moods and a calm, focused mental outlook (R, R2, R3).

Sun and Dopamine

Light also increases dopamine release and the dopamine DRD2 receptors (R, R2R3).

In Seasonal Affective Disorder (SAD), symptoms include lethargy, worsened reflexes, weight gain and low motivation, which all suggest a less functional dopamine system.  In these people, dopamine transporters are reduced in dopamine-rich areas (striatum) (R).

Acute bright light exposure (7000 lux for 10 min) increased blood flow in dopamine-rich areas of the brain (striatum) in healthy volunteers (R).

In Parkinson’s, where dopamine neurons are damaged, light exposure (1000–1500 lux, 1 hour daily for 2 weeks) improved mood, social activity and motor function and, in some cases, reduced medication for dopamine replacement by 13%–100% (R).

Consistent with this, the dopamine DRD2 and DRD3 receptors were greater in people who got more sunshine (R).Patients with symptomatic SAD also show evidence of altered DA system function, and, compared with healthy controls (R).

In patients with SAD, neurotransmitter/catecholamine depletion reversed the therapeutic efficacy of bright light, which shows that the effects are mediated by neurotransmitters (R).

Finally, rodents kept in constant darkness showed increased destruction of neuronal cells that release neurotransmitters — changes that were associated with behavioural alterations indicative of a depressed state (R).

Even when precursors to dopamine were depleted, mood and agreeableness still increased from bright light, which shows that it works on the receptors or transporters (R).

Sun and Vitamin D

In older individuals, low vitamin D levels are associated with low mood (R).

Actually, a 2008 study concluded that people with clinical depression have vitamin D levels 14% lower than normal (R).

One study found that vitamin D levels correspond to the mood of women with diabetes (R).

An interesting study found that bipolar patients recovered faster if they had a window facing east to the morning sun (R).

In Australia, rates of suicide amongst middle-aged people increase in winter when sunlight is minimal (R).

The impact of sunlight on mood might have something to do with the dense number of vitamin D receptors in the hypothalamus (R).

Sunlight also increases relaxation and contentment by increasing beta-endorphins – the same chemicals responsible for “runner’s high” (R).

6) Sun Exposure is a Nootropic and Improves Brain Function

One study found that sun deprivation leads to cognitive impairment (R).

In another study, even brief exposure to sunlight substantially increased participant’s alertness and thinking ability. Increased alertness was due to increased activity in part of the brain called the thalamus (R).

In elderly women, vitamin D deficiency leads to cognitive impairment (R).

Certain wavelengths found in natural sunlight affect the activity of brain structures involved in alertness e.g. by increasing activity in networks involved in ongoing nonvisual cognitive processes (R).

Many researchers have argued that it is no coincidence that large numbers of Vitamin D receptors are found in the areas of the brain involved in complex planning, processing, and the formation of new memories (R).

7) Sun Exposure Protects Against Brain Disorders

Schizophrenia

Low vitamin D levels increase risk of schizophrenia and depression (R).

2,000 IU or more of vitamin D per day, during the first year of a child’s life, can reduce the risk of developing schizophrenia in later life (R).

Alzheimer’s

One study found that, of the 80 participants with Alzheimer’s disease, over half had low vitamin D levels, which suggests that they aren’t getting enough sun (R).

Subjects with Alzheimer’s were exposed to bright light significantly less than healthy controls (0.5 vs. 1.0 hr).  Healthy elderly received about two-thirds the duration of bright light received by healthy younger subjects (R).

There is an association between decreased exposure to bright light and the declines in sleep quality which typically accompany normal and diseased aging (R).

People with Alzheimer’s had disturbed circadian rhythms (R) and sun is critical to circadian rhythms.

Red to infrared light therapy (λ = 600–1070 nm), and in particular light in the near infrared (NIr) range, is capable of arresting neuronal death.  This therapy is being explored for Alzheimer’s and Parkinson’s patients (R). Sun contains infrared.

Increased light exposure consolidates sleep and strengthens circadian rhythms in severe Alzheimer’s disease patients (R).

Parkinson’s

In Parkinson’s, light exposure (1000–1500 lux, 1 hour daily for 2 weeks) improved mood, social activity and motor function and, in some cases, reduced medication for dopamine replacement by 13%–100% (R).

8) Sunbathing Encourages Dental Health

Sun exposure and subsequent increases in vitamin D levels reduce the formation of dental cavities (R, R2).

In agreement, studies have determined that people who live in sunny locations have fewer cavities, and vice versa (R, R2).

Children with severe early childhood cavities are more likely to have vitamin D deficiency (R).

Vitamin D concentrations at or above 30–40 ng/ml should significantly lower the formation of dental caries (R).

Another study on children found that 800 IU/day of vitamin D was enough to prevent cavities in children (R).

In dogs, increasing vitamin D levels led to increased calcification of the teeth (R).

9) Sun Exposure May Reduce Diabetes

Vitamin D deficiency has been associated with insulin resistance, type 1 and 2 diabetes, and metabolic syndrome (R).

One study showed that, in Hispanic whites and Mexican Americans, there is an inverse relationship between Vitamin D levels and diabetes (R). Getting sun might be even more important for people who have ancestry from hot countries.

One study found that UV exposure lowered weight gain, glucose intolerance and insulin resistance, in male mice fed a high-fat diet. The same benefits were not seen with vitamin D supplementation. The benefit of sun exposure may be partly due to the production of nitric oxide, a natural gas, in the skin (R).

Low blood vitamin D levels from inadequate sun exposure may promote the development of type 1 diabetes. Indeed, individuals with autoimmune type-1 diabetes have low levels of Vitamin D (R).

Vitamin D receptors are present in the pancreas, increasing insulin secretion and sensitivity (R).

One study demonstrated a 60% improvement in insulin sensitivity resulting from vitamin D treatment, a treatment more potent than with either troglitazone or metformin (R).

10) Sun Increases Wakefulness

Studies demonstrate that daytime exposure to bright light causes a significant decrease in sleepiness early in the evening. These changes are not necessarily associated with Vitamin D levels (R).

The effects are partly mediated by dopamine and orexin.

11) Sunlight Increases Sex Hormones

Sunlight raises sex hormones. Farmers use this mechanism to increase the laying rate of their hens (R).

A human study found that five treatments of UV light were enough to double sex hormone levels (R).

Studies show that, over the course of a summer, testosterone increases by roughly 20% (R). This effect is amplified when the genitals are exposed to the sun.

12) Sunlight is a Natural Pain Killer

One study found that post-surgery exposure to sunlight decreases stress and pain. Thus minimizing the need for painkillers by 21% (R).

The pain killing effects of sunlight are probably due to its ability to increase beta-endorphins in the skin. Beta-endorphins are natural pain killers (R).

In one study, 88% of people with chronic pain had Vitamin D deficiency (R).

13) Sunlight is Good For Your Eyes

Studies have shown that children who get more exposure to natural sunlight have a lower risk of developing myopia – short-sightedness (R).

Similarly, another study demonstrated that exposure to natural outdoor light reduced defocus-induced short-sightedness in monkeys (R).

14) Sun Exposure Treats Arthritis

Increasing sunlight exposure and blood Vitamin D levels decreases knee cartilage loss in those with arthritis (R).

15) Sun Protects Against Autoimmunity

UV suppresses the immune system (R).

Observational studies linking vitamin D deficiency and insufficiency with increased prevalence of autoimmune and other diseases driven by immune processes (R).

Randomized controlled trials of vitamin D supplementation to treat these (and other) diseases have been disappointing (R).

In Australia, the highest incidence of multiple sclerosis and asthma has been reported in Tasmania (further from equator), with the rate of multiple sclerosis in Tasmania being seven times higher than in Northern Queensland (closer to equator) (R).

The incidence of type 1 diabetes is also influenced by the degree of latitude and UVB light (R).

The link between reduced UVR exposure and increased autoimmune disease has been exemplified dramatically by the enhanced incidence of multiple sclerosis in Iran after the re-introduction of stricter Islamic traditions.  With increased covering up of the skin of females in the last few decades, there has been a significant increase in the incidence of this autoimmune disease (R).

In 115,172 individuals born in the UK, the distributions of births for people with immune-mediated diseases (multiple sclerosis, type 1 diabetes, rheumatoid arthritis, ulcerative colitis, systemic lupus erythematosis) peaked in April and troughed in October (R).

IBD patients have lower vitamin D levels (R).

Some of the immune suppression is from vitamin D and some isn’t.

UVR can suppress the symptoms of the mouse model of multiple sclerosis, asthma and allergies (R).

UVR suppressed the severity of the mouse model of multiple sclerosis even when there were minimal changes in vitamin D3 levels. UV-induced immunosuppression was not affected by the loss of the VDR in mice i.e. the extent of immunosuppression was similar in mice with and without the product of the VDR gene expressed (R).

In one study, UV-induced immunosuppression was not affected by the loss of the VDR in mice i.e. the extent of immunosuppression was similar in mice with and without the product of the VDR gene expressed (R).

Surprisingly, in one study, the symptoms and intensity of experimental MS in mice is significantly reduced when the mice are vitamin D3 deficient (R).

There are many mechanisms by which UV suppresses the immune system (R).

16) Sun Fights Acne

Blue light has been shown to inactivate P. acnes bacteria. Daily self treatment using a blue light treatment for mild-to-moderate inflammatory acne reduced the number of acne lesions significantly (R).

Red light is less effective at inactivating P. acnes than blue light but penetrates much deeper (R, R1,).

The combination of blue and red light works far better than either used alone. Broad-spectrum continuous-wave visible light therapy is used to harness the power of both blue and red light (R, R1)

Topical aminolevulinic acid, methylaminolevulinic acid, or other photosensitizing agents, applied before the laser treatment, improve the outcome of the treatment by decreasing oil gland activity (R).

Infrared light at 1450nm wavelength successfully helps treat acne, possibly by heating the oil gland and reducing its production of oil (R).

Therefore, sun can help acne.

When Sun Might Be More Important

While there are many genes that are regulated by sun, two of them here might be particularly important.

SelfDecode is a powerful app to analyze your snps from companies such as 23andme and others.

If these genes are not working well, you will need more sun:

Mechanisms by Which Sun Benefits Health

Sun increases or provides:

  • Contains Infrared, which has a myriad of benefits
  • Contains Full Spectrum Light, which increases dopamine and serotonin and certain spectrums can improve mitochondrial function (red light)
  • Increases MSH and MC4R receptors
  • Increases Beta-endorphins, which improves mood
  • Relaxes the nervous system and makes us calmer
  • Increases Nitric Oxide, which helps improve blood flow
  • Increases Vitamin D
  • Increases Heat shock proteins
  • Lowers inflammation (UV is an immunosuppressant)
  • Improves Blood flow – blood flows where UV shines
  • Increases metabolism
  • Is anti-Microbial – sun can irradiate large amounts of blood – against fungi, bacteria viruses, etc…
  • Increases CD8 Cells, which help immune system
  • Increases synthesizes sulfhydryl groups (necessary for glutathione)
  • Breaks down adrenaline, estrogen, cortisol, prolactin, progesterone (and testosterone)

Recommendations

What determines “optimal” sun exposure? The amount of sun that is optimal or excessive will depend on your skin type, health status and your latitude (R).

For example, in half-hour of summer sun, a pale skinned person can produce 50,000 IU (1.25 mg) vitamin D. In a tanned person, this exposure creates 20,000–30,000 IU, and 8,000–10,000 IU in dark-skinned people (R)

I recommend that people start off with 10 minutes of sun exposure per day and slowly build up until they reach the point just before their skin turns pink. Eventually, I think building up to at least one hour of sunlight per day is great.

When you are in the sun, try to get as naked as socially acceptable. Your chest and back are your solar panels when it comes to sunbathing.

If for some reason you can’t get sun exposure you might consider taking a high-quality Vitamin D3 supplement. This cannot replace the sun and you should only use it temporarily.

Safety

If you are sensitive to the sun, you should avoid the midday summer sun (R).

I do not recommend using sun creams because most have toxic chemicals in them. Instead, it’s better to put on some clothes, or just get out of the sun.

If you have to stay sun exposed, then you should use a non-nano zinc oxide cream with as few ingredients as possible. This one is not too bad.

Bipolar

There was a large relationship between higher sun exposure and a lower age of onset of Bipolar.

A large springtime increase in sunlight may have an important influence on the onset of bipolar disorder, especially in those with a family history of mood disorders (R).

Why People May Get Skin Cancer From Sun

  • We get too much sun in one shot
  • We don’t build up exposure gradually (we take a vacation)
  • Circadian rhythm dysfunction (circadian processes protect us from sun)
  • We have lower NAD+ (which is our natural sunscreen)
  • We have a bad diet
  • We shower and take off protective oils
  • We don’t spread out the sun (gets concentrated in specific places),
  • We don’t consume enough DHA
  • We don’t drink enough water

Written by Josh Finlay

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The information on this website has not been evaluated by the Food & Drug Administration or any other medical body. We do not aim to diagnose, treat, cure or prevent any illness or disease. Information is shared for educational purposes only. You must consult your doctor before acting on any content on this website, especially if you are pregnant, nursing, taking medication, or have a medical condition.

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9 COMMENTS

  • Alan

    Good fats ingested are the best sun creams …they prorect you from the inside out,avocado,almonds,nuts,cashews,melon seeds…olive oil(extra virgin)…

  • Barry

    Thanks Josh. I get it. I started getting Sun March 9th on Lookout Mountain Georgia. That was the first day the sun was at a 50 degree angle. And I slowly got a tan and started eating chocolate in the morning which protects the skin from sunburn. Also fish and fish oil and cod liver oil protect the skin from sunburn as well as eggs and saturated fat. No vegetable oil here! Sunlight controls over 3,000 genes! Absolutely no sunscreen here! Getting out in the Summer sun is the absolute ticket for good health, a long life, reversal of heart disease, better brain function, lower blood pressure, and a decrease in inflammation, better intuitive abilities, better sleep, better mood, less depression, and seeing the glass half full.

  • Linda Waller

    Last summer I spent lots of hours n the sun doing work in my garden. In the fall I had my annual physical and my blood test showed I still had very low levels of Vitamin D levels. Can someone please explain why this is, thanks.

    1. Nattha Wannissorn, PhD
  • Mike

    Hey, I would be curious on research on UVA/UVB versus UVB alone which is featured in many ‘Vitamin D lamps’. UVB is generally the one they put in these lamps because it creates vitamin D but could that create any kind of imbalance without the UVA? Is there anything they’ve found UVA is good for that UVB is not?

  • Emmie

    Could this mean that people with Bipolar disorder should avoid the sun ? ?

  • Bailey Cummings

    The part I copied and pasted below is misleading because the light therapy was done right before bed which helped Parkinson’s patients because it suppressed melatonin. Although maybe it also helped them due to increased blood flow. Hard to say would need different or better study/studies to confirm.

    Acute bright light exposure (7000 lux for 10 min) increased blood flow in dopamine-rich areas of the brain (striatum) in healthy volunteers (R).

    In Parkinson’s, where dopamine neurons are damaged, light exposure (1000–1500 lux, 1 hour daily for 2 weeks) improved mood, social activity and motor function and, in some cases, reduced medication for dopamine replacement by 13%–100% (R).

    Consistent with this, the dopamine DRD2 and DRD3 receptors were greater in people who got more sunshine (R).Patients with symptomatic SAD also show evidence of altered DA system function, and, compared with healthy controls (R).

  • Jason

    So what is bad about sunscreen? The Zinc Oxide? For me there is no other option than to wear a lot of sunscreen throughout the day. If I don;t I peel and get spots all over.

    1. Live

      Peanut oil is a natural sun screen

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