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While it is wise to avoid burning or excess tanning from solar or indoor ultraviolet radiation, it should be realized that solar UVB radiation (290-315nm wavelength) is the primary source of vitamin D for most people. Dietary sources are generally inadequate, and supplements have to be used carefully.
As for melanoma and other skin cancer, a couple of points should be made. First, while ultraviolet radiation generates free radicals that can do damage, dietary antioxidants and skin pigmentation are nature's way of fighting free radicals. A paper by Millen et al. reported that diets high in antioxidants and low in fats and alcohol can reduce the risk of melanoma by about 50% [Diet and melanoma in a case-control study. Cancer Epidemiol Biomarkers Prev. 2004 Jun;13(6): pp.1042-51].
Second, occupational exposure to ultraviolet radiation is associated with reduced risk of melanoma [Kennedy et al., Leiden Skin Cancer Study. The influence of painful sunburns and lifetime sun exposure on the risk of actinic keratoses, seborrheic warts, melanocytic nevi, atypical nevi, and skin cancer. J Invest Dermatol. 2003 Jun;120(6): pp. 1087-93].
Function; Reasons For Use
Vitamin D is manufactured in the skin following direct exposure to sunlight. The amount of vitamin D produced in the skin varies depending on time of day, season, latitude and skin pigmentation. Usually 10-15 minutes exposure of hands, arms and face two to three times per week (depending on one's skin sensitivity) is enough to satisfy the body's vitamin D requirement. Use of sunscreen markedly diminishes the manufacture of vitamin D in the skin, as does window glass, clothing and air pollution. The fairer your skin color, the more vitamin D you make. As adults age, their ability to make vitamin D through the skin decreases. People who are housebound and experience no sunlight exposure are unable to make vitamin D.
The health benefits of UVB through production of vitamin D are considerable, with more benefits being recognized at a rapid pace. It has been estimated that half of those with multiple sclerosis in the U.S. would not have MS if they had as much UVB exposure as those living in the southern states.
Directions
Mid-day summer sun is the best source of UVB, since minimal exposure times are required, and the UVB to UVA (315-400nm) ratio is highest. If using sunscreen, it might be advisable to go into the sun for 10-15 minutes without sunscreen to generate a day's worth of vitamin D.
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Sunlight Exposure can help with the following: | | | | | Autoimmune |  Vitiligo |
Environment / Toxicity |
 Seasonal Affective Disorder (SAD) | For more than 15 years, patients have used light therapy for the treatment of SAD either individually or under the direction of a medical practitioner. The most commonly used and studied form of light therapy involves the use of a light box that administers bright light during a particular time of day, usually in the morning but sometimes in the evening. More recently developed but less studied forms of light therapy include dawn light simulation and the use of light visors. The antidepressant effects of light therapy are thought to be mediated through the eyes, not through skin exposure.
Combinations of the three components of light therapy (timing, intensity and duration) can affect the outcome of treatment. Long-term efficacy has not been established, and the intensity-response relationship, the optimal treatment schedule, and the long-term safety of light therapy have also not been clarified.
Although there as been controversy about the importance of timing, studies have confirmed that, on average, morning light therapy is superior to evening light exposure. The wavelength or type of light (incandescent, fluorescent) is not as important as intensity, but white light may be superior to narrow band wavelengths. Ultraviolet wavelengths are not necessary for the antidepressant response, and should be avoided because of long term toxicity.
Light intensity is usually expressed in "lux", a unit of luminance. As a reference, indoor lighting is usually less than 500 lux, outdoor light on a cloudy day ranges from 1,000 lux to 5,000 lux, and midday summer sunlight can reach 50,000 lux or higher. The usual dose of light therapy used in previous studies was 2,500 lux for at least one to two hours per day, but further research showed similar benefit with 30 minutes of 10,000 lux exposure. Since shorter periods of exposure are more convenient, the 10,000 lux fluorescent light box has become the clinical standard.
Commercial light devices are now widely available in medical supply stores or through mail order. A light device should meet government electrical safety standards, have a filter for the ultraviolet wavelengths and have been tested in reputable clinical trials. Patients must maintain proper distance and positioning to ensure the correct dose of light exposure. Because of the rapid response and relapse with light therapy, patients should become involved as active participants in determining their optimal dosing of light. For example, if patients respond to early morning light exposure, but the time is inconvenient for them, they can try shifting the exposure time to afternoon or early evening. Alternatively, they can try to reduce the duration of exposure to 15 minutes for maintenance.
Some response to light therapy generally occurs within two to four days, and measurable improvement is often seen in one week. Most patients experience rapid recurrence of symptoms after discontinuing light therapy. Longer trials have shown increasing improvement after two weeks, and further gains at three or four weeks.
The common side effects of light therapy reported by patients in clinical trials include eye strain or visual disturbances (19%-27%), headache (13%-21%), agitation or feeling "wired" (6%-13%), nausea (7%), sweating (7%) and sedation (6%-7%). These side effects are generally mild and subside with time or by reducing the dose of light. Extreme mood shifts have also been reported as uncommon but serious side effects of light therapy.
Light therapy should be administered under the guidance of an experienced and trained medical professional to properly diagnosed patients who have no psychotic disorder and who are not suicidal. Light therapy continues to be an investigational treatment, but with well-established benefits for users. |
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Hormones |
 Low Melatonin Level| | You can improve your melatonin levels by going outdoors and turning yourself toward the sun for at least 15 seconds. You do not need to keep your eyes open, but rather blink in the direction of the sun. It is best to do this during the times of day that avoid the 2 hours either side of noon, so the sun will be less intense. The most perfect times are near or at sunrise and sunset. You can increase the time you "gaze" at the sun by 10 seconds each day, with a maximum of 30 minutes per day. Then, as you drive or spend other time outdoors, eliminate the use of sunglasses. This will help your sleep cycles and your melatonin levels by eliminating the brain confusion associated with darkened rooms and eyecoverings. It has also been shown to be helpful with endocrine balances in general. |
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Mental |
Panic Attacks| | A study found that 9 of 22 patients had panic attacks more frequently in winter. |
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Metabolic |
Bulimic Tendency |
Musculo-Skeletal |
Osteoporosis - Osteopenia| | Habits to curtail include heavy smoking, excess alcohol consumption, and limited sunshine exposure or vitamin D intake. |
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Skin-Hair-Nails |
Psoriasis| | Summer sun is the best source of ultra-violet light, and many people find psoriasis settles very well in summer. Treatment in winter can be aided by artificial lamps: smaller lamps are usually not strong enough, but impulse type lamps, wall mounted "fluorescent lamp type" lamps, and larger "solarium" lamps are suitable. Unfortunately, some psoriasis sufferers are rather sensitive to sun light, and may not be improved with this treatment.
It is usually best to apply a tar or drithanol preparation daily, to be followed later by ultra-violet light treatment. |
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Sunlight Exposure can help prevent the following: | | | | | Nutrients | Vitamin D Requirement| | People should aim to get 10 to 15 minutes of exposure to direct sunlight each day when the weather allows, without sunscreen, to allow adequate synthesis of vitamin D. Most people achieve this simply by going about their daily activities. Those living at higher latitudes (further from the equator) should supplement their diets to ensure they are getting enough vitamin D, particularly during winter. A lack of sun during the winter months means that many people are deficient in this vitamin by December each year.
In the spring and summer, light-skinned adults can make large amounts (20,000 IU) by sunbathing on both sides, without sunblock, for a few minutes (about one-third the time it takes for the skin to begin to slightly redden). Darker-skinned persons need five to 10 times longer depending on the amount of melanin pigment in the skin.
Vitamin D production occurs within minutes and is maximized long before the skin turns red or begins to tan. One does not have to get repeated blood tests when using sun exposure to obtain vitamin D. Toxicity can not occur even with heavy and continuous sunbathing because ultraviolet light begins to degrade vitamin D after making about 20,000 IU, thus reaching a steady state. |
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Tumors, Malignant |
Cancer, General| | Staying out of the sun completely may increase your chances of developing cancer, say doctors. For years, experts have advised people to cover up in the sun to protect themselves from skin cancer. A letter in the British Medical Journal (November, 2003) from professor Cedric Garland of the University of California warns people against taking this advice to the extreme. He says that a lack of sun can reduce levels of vitamin D, which may increase the risk of cancer. Studies have suggested that vitamin D can protect against colon, breast, prostate and other cancers. |
Ovarian Cancer| | Vitamin D metabolite receptors are found on endocrine and reproductive organs and are known to play a role in inhibiting a number of cancer cell lines. The incidence of ovarian cancer varies with latitude, with higher rates in northern parts of the world. In this study, the quantity of sunlight was strongly inversely correlated with the incidence of death due to ovarian cancer in 100 of the largest US cities (1979-88) after adjustments were made for air pollution levels. Northern women in the 5th decade of life were found to have 5 times the mortality rate from ovarian cancer as southern women. [Epidemiol 23 (6): pp.1133-36, 1994] |
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KEY | | May do some good | | | Likely to help | | | Highly recommended |
GLOSSARY
Actinic Keratoses
Actinic keratoses are common premalignant skin tumors that appear as small, raised, flaky lesions usually found on heavily sun-exposed skin in older people. They are mainly due to long-term exposure to the sun in susceptible persons and may progress to squamous cell carcinoma.
Antidepressant (Antidepressants)
Literally, substances meant to oppose depressions or sadness, and generally heterocyclic types such as Elavil, MAO inhibitors like phenelzine, or lithium carbonate. This category of substances formerly included stuff like amphetamines and other stimulants. Botanical examples include Hypericum, Peganum and Oplopanax.
Antioxidant (Antioxidants)
A chemical compound that slows or prevents oxygen from reacting with other compounds. Some antioxidants have been shown to have cancer-protecting potential because they neutralize free radicals. Examples include vitamins C and E, beta carotene, the minerals selenium and germanium, superoxide dismutase (SOD), coenzyme Q10, catalase, and some amino acids.
Cancer
Refers to the various types of malignant neoplasms that contain cells growing out of control and invading adjacent tissues, which may metastasize to distant tissues.
Colon (Colonic)
The part of the large intestine that extends to the rectum. The colon takes the contents of the small intestine, moving them to the rectum by contracting.
Free Radical (Free Radicals)
A free radical is an atom or group of atoms that has at least one unpaired electron. Because another element can easily pick up this free electron and cause a chemical reaction, these free radicals can effect dramatic and destructive changes in the body. Free radicals are activated in heated and rancid oils and by radiation in the atmosphere, among other things.
IU (mIU, uIU)
International Unit: An arbitrarily defined but agreed upon unit that depends on what is being measured.
mIU: 0.001 or one thousandth of an IU.
uIU: 0.000001 or one millionth of an IU.
Melanin
A dark pigment produced in the skin. Dark-skinned individuals produce more melanin, and melanin production increases in response to sunlight, causing the skin to become darker.
Melanoma
A life-threatening type of skin cancer that occurs in the cells (melanocytes) that produce melanin, the pigment found in skin, hair, and the iris of the eyes.
Melatonin
The only hormone secreted into the bloodstream by the pineal gland. The hormone appears to inhibit numerous endocrine functions, including the gonadotropic hormones. Research exists on the efficacy of melatonin in treating jet lag and certain sleep disorders. Dosages greater than l milligram have been associated with drowsiness, headaches, disturbances in sleep/wake cycles and is contraindicated in those who are on antidepressive medication. It also negatively influences insulin utilization.
Metabolite (Metabolites)
Any product (foodstuff, intermediate, waste product) of metabolism.
Mole (Moles, Nevi, Nevus)
Known more accurately as a "nevus", a mole is a lesion of the skin that may be present from birth, but which most often appears later in life. By three years of age, 40% of children will have at least one nevus. Some varieties are hereditary and most have color. A common nevus in light-skinned people is typically small, round, tan or brown, with a smooth border, and exactly the same throughout. Other types may be very large, or have irregular borders. There are dozens of different types, with many shapes, colors and sizes. While most are benign, malignant changes can occur to turn the benign nevus into a melanoma.
Multiple Sclerosis (MS)
Demyelinating disorder of the central nervous system, causing patches of sclerosis (plaques) in the brain and spinal cord, manifested by loss of normal neurological functions, e.g. muscle weakness, loss of vision, and mood alterations.
Nausea
Symptoms resulting from an inclination to vomit.
Panic Attack (Panic Attacks)
A brief, irrational episode of fear that is perceived as so real that an individual may be driven to escape from the place or situation where it occurs. The attack is sudden and increases in severity until it leaves, usually within ten minutes. Panic attack symptoms are numerous and involve both mental and physical signs and symptoms. A panic attack can occur in other anxiety states such as agoraphobia and with certain activities and places. It may occur spontaneously without an apparent cause.
Prostate
The prostate gland in men that surrounds the neck of the bladder and the urethra and produces a secretion that liquefies coagulated semen.
Psoriasis
An inherited skin disorder in which there are red patches with thick, dry silvery scales. It is caused by the body making too-many skin cells. Sores may be anywhere on the body but are more common on the arms, scalp, ears, and the pubic area. A swelling of small joints may go along with the skin disease.
Seborrhea (Seborrheic)
Skin disease characterized by dry or moist, greasy, yellow crusts or scales. A disorder of the sebaceous glands, with changes in the amount and quality of the oils secreted. Although it can occur in any part of the body, seborrhea of the scalp (dandruff) is most common.
Vitamin D
A fat-soluble vitamin essential to one's health. Regulates the amount of calcium and phosphorus in the blood by improving their absorption and utilization. Necessary for normal growth and formation of bones and teeth. For Vitamin D only, 1mcg translates to 40 IU.
Last updated: Apr 13, 2008
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