Let The Sun Shine Through

by Ronald D. Whitmont, M.D.

Recently the sun's been getting a lot of negative press: "Don't go in the sun, you'll get skin cancer," or "There's no ozone left, it's dangerous to be outside!" Many of our physicians tell us to use sunscreens and slather it on our children. It's as if our mother star had turned on us like a bad parent.

But these cautionary words do not represent scientific reality so much as a distortion of the truth that can easily slip into misinformation. In fact the right amount of sunlight is important for maintaining a healthy mind and body. Too much of anything, including sunlight, can be an extremely dangerous thing. Yet too little can be just as devastating.

The seasons of the earth as well as the seasons of our lives are linked with the sun and its rhythms. The sun is worshipped in many cultures as a provider of prosperity and strength. Mythologically, we link the sun with the heart. It is represented by the metal, gold, which we have traditionally used to symbolize love and power. The return of the sun in spring marks the reawakening of soul to love and life.

Sunlight not only plays an extremely important role in nature, but a pivotal role in many biochemical and physiological processes within our bodies as well. Exposure to natural sunlight stimulates the body to produce a number of different hormones that regulate our daily rhythms of sleep and wakefulness, balancing salt and water concentrations while affecting organs like the heart, the kidneys, the brain and the immune system. The effect of these symphonies of hormones in our body is extremely complex and directly linked to natural rhythms orchestrated by the sun. "Threads establishing a connection between exposure to sunlight and blood pressure or risk of heart disease and stroke have already been elucidated and only await further study."

Seasonal Affective Disorder (SAD) is just one emotional effect of getting too little sunlight in our daily cycle. Many of us are familiar with SAD, which used to be called Winter Blues and Cabin Fever. The depression that marks SAD is either caused or aggravated by seasonal changes in the sun's light. We don't know if it is the ultraviolet radiation or the visible spectrum that helps avert this illness, but we do know that when we are exposed to longer days and more temperate climates the condition tends to improve.

Sunlight contributes to the development and maturation of a certain subset of Lymphocytes known as T-lymphocytes, a type of white blood cell, in the human immune system. These cells originate in the thymus and migrate to the superficial layers of the skin where they are exposed to sunlight and ultraviolet radiation. The radiation appears to play some role in their maturation. These cells go on to become integral to our defenses against viral and bacterial infections, but they are also integral to the body's defenses against cancer and other illnesses involving the immune system. While too much sunlight impairs the functional ability of these cells, too little sunlight has the same effect. Sun blocks and sunscreens that block ultraviolet radiation interfere with this process.

The benefits of sunlight and ultraviolet radiation have been long appreciated by those with a variety of skin afflictions, including many forms of eczema and psoriasis. By some unknown mechanism regular, moderate exposure to the sun sends many of these conditions into permanent remission.

Osteoporosis develops when bones miss enough of the mineralization, predominantly calcium, that, much like the cement on the steel rods of a bridge, helps add rigidity to the matrix of protein support. Most people know it's important to have an adequate daily intake of calcium to prevent osteoporosis, but are unaware of the role of sunlight in making calcium available to the body. Yet there is a direct correlation between lack of adequate sun exposure and the risk of developing osteoporosis. This is most readily apparent when we look at the incidence of osteoporosis as the distance from the equator increases. Northern climate, lack of sunlight, and the use of sun blocks all increase the likelihood of developing this condition. The ultraviolet radiation in sunlight is essential in helping the body convert free cholesterol into vitamin D in the skin. Vitamin D in the intestines assists in the absorption of calcium, while in the kidneys it prevents calcium loss through urination. It is also possible, though not yet known, that the conversion of cholesterol into vitamin D by ultraviolet light may reduce the body's total cholesterol level, and thus bring a dual benefit.

Sunlight normally directs a subset of skin cells known as melanocytes to produce more of the dark pigment known as melanin. Melanin is the substance responsible for the dark skin of those from African, Asian or Mediterranean descent. It is also responsible for creating suntans. The dark pigmentation known as melanin is the body's unique way of providing natural protection from many of the sun's damaging effects. Dark skin pigmentation through birth or sun tanning provides a high degree of natural protection while allowing the sun to continue to bestow beneficial effects on our bodies.

Most dermatologists agree that sun tanning is not harmful when it is achieved by regular moderate exposure to the sun. Too rapid or intense exposure after prolonged avoidance can be harmful because the absence of pigment allows the sun's rays to penetrate more deeply into the skin, reaching sensitive structures and causing damage to genetic material. Sunburns are the result of unprotected exposure to massive amounts of damaging radiation. Sunburns do not occur if there is regular, graded, exposure to the sun throughout the year. "Weekend warriors" and seasonal tourists are at greatest risk of being damaged by the sun. A safe, practical approach to the sun includes regular exposure in increasing levels until the skin naturally pigments and tans. Maintaining this exposure once pigmentation is present is not only safe, but thoroughly advisable, on a lifelong basis.

According to Dr. Martin Weinstock, Director of the Department of Dermatoepidemiology at the Rhode Island Pigmented Lesion Unit at Brown University School of Medicine in Providence Rhode Island, "constant, consistent exposure to sunlight is far superior to short intense periods followed by periods of little or no sun exposure." The harmful effects of sunlight on the skin are the direct result of too much sunlight over too short a period of time. Dr. Weinstock adds that "there is no conclusive evidence that sunscreen use reduces the risk of melanoma."

According to Dr. Marianne Berwick, an epidemiologist at Memorial Sloan-Kettering Cancer Center in Manhattan "the use of sunscreens may actually increase the risk of developing skin cancer." Sunscreen products do prevent sunburns from developing, but they may expose us to an increased risk of damaging our skin. There are several reasons for this, but essentially these products are "screens" that only block some of the spectrum of radiation reaching us from the sun, not all of it. By blocking some wavelengths of radiation and letting others through, a sunscreen may interfere with the sun tanning-pigmenting process (that provides protection from the sun), yet allow other harmful wavelengths of radiation to penetrate deeply into the skin, causing damage to cellular structures without the helpful warning signs of burning or pain. Thus a heavy dose of sunlight on a sunscreened individual may actually do more damage than it would to an unprotected individual, who could not only produce some level of pigment but would be able to feel enough of a burn to know it was time to get out of the sun. Preliminary research results, which are necessarily controversial, indicate that sunscreen products, however reasonable a solution for preventing sunburn, may prove to be a deadly mistake as a defense against cancer.

To summarize:
1) Sunlight, in moderate amounts is not only safe, but it is extremely beneficial for growing healthy bodies, minds and immune systems. There are physical and emotional benefits that have been well described and noted. Regular exposure to the sun without blocks or sunscreens should be encouraged from an early age in most individuals.
2) Excessive sunlight exposure is hazardous to the skin and the immune system. Sunscreens may provide protection from burning, but may increase the risk of long term health problems without providing other benefits in most individuals. The use of these products should not be a routine part of summer, but should be used cautiously and judiciously, with knowledge of the risks involved.