If the exposure to sun light is moderate, the benefits outnumber the dangers. First of all sunshine has a good effect upon the mental health and well-being, both due to the visible light and to the warming effect.
The UVA rays in the sunlight stimulates the skin to produce vitamin D. This vitamin is necessary for the normal composition, growth and regeneration of bone tissue. By to low levels of vitamin D in the body, the bones tend to loose calcium and get thinner and weaker. Newer findings suggest that many people do not get enough of this vitamin through the diet or do not absorb enough from the intestines, and need this stimulation to get good enough levels of vitamin D.
Newer findings also suggest that moderate amount of sunshine does not promote the occurence of skin cancer. On the contrary, in moderate amounts, exposure to sunshine seems to help prevent cancers of several types., especially breast cancer, colon cancer and prostate cancer.
The benefit that most people go for when engaging in sun bath, is the browning effect. This effect comes from the UVA rays stimulating the melanocytes in the skin to produce more of the brown pigment - melanin. The increased amount of melanin will protect the skin against the harms of sun-rays, and make you tolerate greater amounts of sun before harmful effects occur. The sun rays also stimulate the upper layer of the skin to grow thicker, and this makes the skin more robust against damage. As long as this thickening is moderate, the thickening is a good effect.
THE DANGERS OF THE SUN-RAYS
The most visible danger of exaggerated sun exposure is the burning effect caused by the UVB rays. The effect is mostly due to immune cells in the skin releasing histamine. Histamine then causes blood vessels to dilate and also cause other symptoms of acute inflammation. Some cells will also be injured by the sunlight to such extend that they die, causing the upper layer of the skin to flake away.
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Exaggerated exposure to sun can cause brown spots - liver-spots. Furthermore it can cause the cancer type called basal cell carcinoma. These effects are caused both from the UVA and UVB rays. This type of cancer looks like brown flakes or brown spots, and may be difficult to distinguish from liver-spots. However, this kind of cancer is little malignant, and is in many cases just a cosmetic problem.
But the UVA and UVB rays from too much sun exposure can also cause malignant melanoma. This cancer consists of melanocyte cells been transformed into cancer cell. Malignant melanoma often evolves from birth marks. This cancer can remain small for a long time, but can also spread and develop very rapidly and swiftly evolve into a serious disease. In its initial stages, the cancer looks like an irregularly shaped and abnormally or irregularly coloured birthmark. People having been exposed to much sun and often been sunburned form an early age, are in special risk for malignant melanoma.
Traditionally skin cancers were thought to be caused by the UVB rays, but newer findings suggest that the whole ultraviolet spectre participates in causing cancers. Therefore using solariums that gives off only UVA rays is not safe from cancer risk.
Too much sun exposure for a long time will increase the speed of skin aging and cause permanent changes in the skin, due to the effects of UVB rays. The wrinkles will multiply and aggravate. Also the blood vessels in the skin tend to become permanently dilated and areas of the skin will often get an abnormal or irregular thickness, some places too thin, other places too thick. Due to the widened blood vessels, the skin will be permanently red.
UVC rays are normally filtered out from by the ozone layer in the upper atmosphaere. Nowadays this layer is wakened over certain areas in certain times. These rays are the most dangerous and easily cause cancer and other types of skin damage.
WHAT IS THE BEST PROTECTION AGAINST SUNLIGHT
The best way to get just enough sun exposure to get the benefits, but not so much to suffer the harms caused by sun rays, is just to expose your skin for the sun some time, and then cover the skin by clothes.
The time recomanded for naked exposure vary considerably. A person with brown skin can take much more than a pale person. The same is true about a person with thick skin. As you get used to the sun each year, you will gradually get browner and also tolerate more. If you take sunbath for the first time in the year, and you have not yet get used to the sun, 10-15 minutes may be enough.
However, often you want to expose your skin to the sun rays longer than an unprotected skin can tolerate, and then you have to use some topical sun protection. Sun balms are found with protection from 3 to 30. The protection factor is supposed to tell how many times longer you can be in the sunshine with the balm on, than without the balm. Be aware that the real protection factor may be less than that written on the bottle.
A balm with the factor 20 does not always really have that factor. If you know you can tolerate 0.5 hours exposure without protection, do not think that you really will tolerate 10 hours exposure with a balm of factor 20 on. The balm must also be renewed several times during the time you expose yourself for the sun. That is especially true if you take swims. The balm must neither be too old.
The face is the body part that it is most important to protect against the sun, since the face does not have any clothes on, and accordingly gets longest sun exposure.
Some kinds of nutrition seems to make the skin more robust against the impact from sun rays. It is for example wise to eat much fish and use olive oil in the diet. You should also attend to the news about the ozone layer, and always protect your skin in periods with weakened ozone layer.
