Morning for Energy, Noon for Body, Evening for Love
If the sun were in a pill, we would happily fork out our life’s savings for one milligram of its miracles. We would of course, as with all medical interventions, have to weigh up the risks and benefits.
Happiness, sleep, energy, thyroid health, immunity, blood pressure, heart health, lifespan, healthy weight, bone health, neurological health, metabolic health, gestational health, fewer allergies, less cancer, less myopia. Perhaps we should send our short-sighted politicians and administrators out into the sun.
For tired brains, skip to the end of this article and rejuvenate by getting out into the sun. For those wanting a deep dive, read on.
You and I Are on This Earth Because of the Sun
While physicists may debate the details of the big-bang, religions and traditions have long acknowledged the sun as life-giving. The sun was said to have been born from the eye of the Hindu primal being, Purusa. The sun played a significant part in the worship of the ancient Egyptians, Romans, Greeks, Aztecs, and Mayans. Pagan holidays align with the seasons. The Christian god when he created the Earth said “Let there be light”.
In the last few centuries, sun worship has been derided by monotheist religions. It has been described as “the most enduring of all the forms of idolatry”. Indeed, the past few decades have seen the sun further maligned due to its association with skin cancer and wrinkles, with scant acknowledgment of its health-giving properties.
The Earth has been bathing in sunlight for over 3 billion years. During photosynthesis, green plants and algae trap solar energy. This trapped energy is converted into glucose that the plant stores starch. It is then passed on to organisms that consume the plant. Thus the sun’s energy is passed up the food chain.
The Energy From the Sun
The sun is a magnificent source of energy. It provides more energy in 1 hour to the Earth’s surface than is consumed by humans in an entire year and by all plants in three months. The sun’s energy is not likely to run out for a few billion years yet!
The sun’s energy is emitted as electromagnetic waves, of which only a fraction reaches the earth. These rays fall within the spectrum of Ultraviolet (UV), Visible, and Infrared (IF) rays. What we see as color is a very small part of the sun’s electromagnetic irradiance. In nature, bright blue light always comes with Ultraviolet rays (UVR). UVA (longer wavelength) and UVB (higher energy) reach the Earth in varying degrees. 94% of UVR that reaches us is UVA and 6% is UVB.
UVB intensity changes much more than UVA does. The higher the sun, the greater the UVB content. There is less UVB in winter, at higher latitudes and either side of midday. UVA generally remains more constant. It has a longer wavelength and partially penetrates glass and clothing and reaches more deeply into the skin. In contrast, UVB does not penetrate past the upper layer of skin, nor does it pass through glass or clothing.
Visible and IF rays penetrate through the skin into the body cavity, bathing the internal organs, where they have unique healing effects. That is for another article.
Sun on the Skin
UVR has both positive and negative effects. However given our indoor lifestyles, no doubt exacerbated by dubious lockdowns, insufficient sun exposure has been described as a “Real Public Health Problem”.
UVB rays have more energy than UVA. This is the energy that stimulates the production of Vitamin D in the skin. It can, however, also cause direct damage to DNA. UVA rays penetrating more deeply into the skin can induce free radicals that then go on to damage DNA and proteins. It is this deeper damage that causes wrinkles and photo-aging.
Thickening of the skin and tanning are normal physiological adaptations to sun exposure. In response to UVR, the upper “dead” layer of skin is increased, reflecting UV rays. Both UVA and UVB rays can trigger darkening of the skin, while sunburn is caused by UVB radiation.
UVB rays stimulate skin cells to produce melanin (natural skin pigment). Melanin acts as an umbrella sitting on top of the nuclei (and thus the DNA) of the skin cells, providing protection. Melanin also acts as an antioxidant, neutralizing free radicals and reducing damage from UVR. This is borne out by darker skin with high melanin content being less prone to skin cancer than lighter skin.
UVA rays do not increase melanin rather modifying existing melanin and changing its dispersal. The darkening of the skin due to UVA is immediate but does not provide any protection against future UV exposure. Thus the new tan from a day at the beach does not afford UV protection for the rest of a two-week holiday.
DNA damage in skin cells is greater after UV exposure in skin that was not previously exposed to UVB or was exposed to UVA only.
The more melanin present in skin cells, the less the DNA damage. The amount of time for UVB to elicit melanin production is difficult to quantify, being influenced by pre-existing pigmentation levels and the dose of UVB. Increased melanin likely occurs at least a few days after UVB exposure.
The biggest source of Vitamin D is sunlight. The few foods that naturally contain Vitamin D include wild-caught salmon, cod liver oil, and sun-dried mushrooms.
The effects of Vitamin D include DNA repair and control of cell proliferation. This means that it helps to prevent cancer from growing. It is known to control or kill melanoma cells, as well as other cancer cells.
Vitamin D has receptors throughout the body. Not only is Vitamin D involved in calcium regulation and bone health but also improves immune function, muscle strength, insulin secretion, red blood cell production, brain function, and hormones.
Skin Cancer: Windows, Holidays, and Sunscreen
Melanoma, the most deadly skin cancer, is associated with fair skin, a tendency to sunburn, red hair, and a large number of moles. There also seems to be a strong genetic component. Melanoma has been increasing in fair-skinned indoor workers since before 1940. Yes, outdoor workers have lower rates of melanoma.
Melanoma is associated with intermittent sun exposure, while continuous sun exposure seems to have a neutral to protective effect. In contrast, other skin cancers, such as Squamous Cell and Basal Cell Carcinomas, are associated with cumulative time spent in the sun. Fortunately, these cancers are less dangerous than melanomas and Vitamin D also helps to stop them.
Thus the factors leading to melanoma are likely to be related to environmental conditions in genetically susceptible individuals. We are not yet at the stage where a simple gene test can tell us how much sun we should get. However, we do have control over our environment.
An interesting environmental hypothesis relates to the fact the UVA penetrates through windows but that UVB does not. This has two significant effects. Firstly there is no UVB to make protective Vitamin D or melanin. Secondly, UVA actually breaks down Vitamin D. Thus office workers are left with the damage from UVA but no protection from either melanin or Vitamin D.
Outdoor workers who are constantly exposed to UVB have a stable level of Vitamin D and melanin. The melanin absorbs UVR and the Vitamin D prevents pre-cancerous melanoma cells from becoming cancerous.
When indoor workers are exposed to bursts of intense UVR, such as experienced on weekends or holidays, DNA damage occurs. Without sufficient Vitamin D, this intermittent UVR exposure may lead to the development of melanoma. Taking vitamin D supplements may not provide protection as the amount of vitamin D locally in the skin may still be insufficient.
Overexposures and especially sunburns from UVB exposures initiate melanoma while UVA exposures and inadequate Vitamin D3 in the skin may promote it.
Sunscreen needs to block UVB to prevent sunburn. Sunscreen often does not block UVA and has not been shown to prevent sunburn outside of laboratory conditions. Sunscreens have been thought to prevent Vitamin D production but this is disputed. However, sunscreens do have deleterious effects on humans and the environment.
Other Potential Harms
Just as UVR can damage protein and DNA in the skin, so it can damage delicate structures in the eyes. Sun exposure is a risk factor for cataracts and macular degeneration. However, it has been argued that the modern diet also significantly contributes to these disorders.
Benefits of Sunlight: Living Longer, Vitamin D, Plus
Given the potential for harm from UVR, one would expect that UVR exposure would shorten life. However, there is no evidence for this. A meta-analysis of 32 studies calculated that sun avoidance was equivalent to smoking for mortality. In a large study of Swedish women, higher sunlight exposure was associated with reduced deaths from all causes.
Many of the benefits of sunlight are not replicated by Vitamin D supplementation. Scientists now suspect that Vitamin D, rather than always having a direct effect on health, is an indicator of sun exposure. It is not always just Vitamin D that we need; we actually need the sun’s rays.
Nitric Oxide, Improving Your Blood Flow
An interesting molecule produced by UVR on the skin is Nitric Oxide (NO). NO dilates blood vessels and lowers blood pressure. It is also a potent antioxidant. Again low Vitamin D levels are associated with poor heart health but low Vitamin D does not cause heart disease. It is more likely that those with low sun exposure have low Vitamin D and low NO; the latter resulting in constriction of blood vessels.
Beta-Endorphin, Making You Feel Goooood
This brain chemical provides us with a feeling of well-being. It also reduces the sensation of pain and enhances relaxation. Beta-endorphin is responsible for the so-called runner’s high.
This molecule is also released in response to UVB. It is why we feel so good in the sun.
Keeping Time, The Rhythm of the Day
Our circadian rhythm is regulated most strongly by blue light via the eyes. This sets off a chain reaction inhibiting melatonin production which lets the body know it is daytime. When less blue light is around, such as in winter, sensitive people may become listless and depressed, developing SAD (seasonal affect disorder).
All cells, including skin cells, keep cellular time via genes known as clock genes. When skin cells are exposed to UVB radiation, they will turn these clock genes on.
Syncing the body clock to the environmental clock has significant benefits for sleep and health. Indeed working against circadian rhythm is associated with a vast array of ill-health, from mood disorders to heart disease to cancer.
But Wait, There’s More
Many of the effects of Vitamin D vs. sun exposure are yet to be teased out. Health effects previously assigned to Vitamin D may be due to sunlight. Lumping these together, sufficient Vitamin D, and by implication, sun exposure is associated with the following.
- Less cancers of the breast and colon
- Less leukemia
- Less cognitive decline
- Less autism
- Less asthma, respiratory infection
- Less eczema, psoriasis
- Less auto-immune disease including Type 1 diabetes, multiple sclerosis, vitiligo
- Less myopia
- Better mood
- Less rickets and osteoporosis
- Less allergy
- Less obesity and type 2 diabetes
- Improved wound healing
- Improved brain function
- Positive interaction with hormones, including thyroid and sex hormones
Vitamin A, Carotenoids and Polyphenols
We tend to forget that we have evolved with multiple stimuli, all of which have an effect on our bodies. Most doctors would scoff at the idea that diet influences our response to UVR. However, it appears that our recent love of processed food, in particular, seed oils exacerbates the damages of UVR.
Carotenoids, some of which are converted into Vitamin A, have been shown to protect against sun damage. Carotenoids occur in colorful vegetables and leafy greens.
Vitamin A plays an important part in UVR protection in the skin. Vitamin A is found in animal foods. There is a strong genetic component to how much plant-based carotenoid is converted to actual Vitamin A. Zinc is also required for this process. So an exclusively plant-based diet may not provide sufficient Vitamin A.
The incidence of skin cancer is less in those with an increased intake of fish, tea, olive oil, vegetables, and citrus fruit. Dietary polyphenols, antioxidants, and omega 3 and 9 are likely to be responsible for these benefits.
The health benefits of the sun are numerous. To access these and the mitigate risk of harm, do the following.
- Eat foods that are high in Vitamin A (egg, salmon, liver, fish, and dairy) and carotenoids (carrots, rockmelon, and dark green leafy vegetables).
- Consume foods high in polyphenols, omega 3, and omega 9. Polyphenols are high in all colorful vegetables and are particularly high in green tea. Omega 9 is found in olive oil.
- Time in the sun for Vitamin D. The amount of time to produce Vitamin D in the skin varies. However, sun exposure needs to be between the hours of 11 am and 3 pm when UVB is prominent. For a fair-skinned person 15–30mins, every alternate day is sufficient. The hands and face do not produce much Vitamin D, so these can be covered. In the following circumstances, a longer time in the sun is necessary: obesity, age, winter, cloudy weather, and air pollution.
- Time in the sun for the benefits of UVB-induced UVR protection. Ideally, you would be in the sun in your bikini or mankini allowing for continuous exposure of your holiday skin. This also needs to be around midday. Do not use sunscreen and start slow.
- Time in the sun for circadian rhythm and general health. Sun exposure for at least 15 mins at dawn, midday, and dusk. Expose at least your arms and legs. Do not wear sunglasses in the morning. We need blue light on the eyes.
- Sun exposure for hormones. Men, sunning your balls may improve testosterone. Seriously.
There’s nothing like the sun that shines today. There’s nothing like the sun till we are dead. Edward Thomas