The darkening of skin after exposure to ultraviolet radiation of sun rays, or a tanning bed is called "sun tanning".
Ultraviolet radiation stimulates a natural physiological response that leads to the darkening of skin. During exposure to ultraviolet radiation, the pigment melanin is produced in cells called melanocytes. The melanin is released into the skin's cells and this darkens the skin. It also protects the body from absorbing an excess of solar radiation. As per an individual's genetic constitution, some individuals darken fast while others do not darken at all.
The UVA and UVB rays are responsible for tanning. The latter have more energy than the former and can cause more damage.
The UVB rays:
The UVB rays:
- foment creation and secretion of new melanin into the skin
- are more carcinogenic (cancer producing) than UVA rays
- create Vitamin D in the system
- are decreased by nearly all sunscreens as per their SPF
- lead to skin aging, but at a slower rate than UVA rays
- may lead to a sunburn due to overexposure
The UVA rays:
- release the pre-existing melanin from the melanocytes
- lead to the oxidization of melanin, which creates the tan color in the skin
- may cause melanoma--a very dangerous skin cancer
- are present more uniformly all over the day and in all seasons as compared to UVB
- are blocked somewhat by clothing and to a lesser degree by sunscreens, unlike UVB
- As sun exposure leads to the production of Vitamin D, it becomes essential for those suffering from a deficiency of the same. It is analyzed that 50,000 to 63,000 deaths occur yearly in the United States due to insufficient Vitamin D. Deficiency of this vitamin can also lead to pain in the bones, difficulty in bearing weight, and could increase the chances of suffering from a fracture.
- Overexposure may lead to sunburns and melanoma.
- Since the ozone layer has been depleted, dangerously high levels of UV radiation enter the earth's atmosphere and thereby increase the incidence and severity of sunburn.
Application of chemicals on the skin to result in an appearance similar to sun tanning is called "Sunless" or "Self" or "UV-free" tanning. The most efficient chemicals are those containing dihydroxyacetone (DHA). Products containing the amino acid tyrosine are also used as tanning accelerators. Canthaxanthin is a color additive used in some foods. Melanotan hormone is a melanocyte-stimulating hormone that is another choice. Bronzers are temporary sunless tanning options.
A chemical reaction takes place between the DHA and the amino acids present on the dead cells of the skin. This is totally non-toxic as well as skin safe and the damage linked with UV exposure is absent. The tan produced is impermanent and fades in 3 to 10 days. If Erythrulose is mixed with DHA, a longer lasting sunless tan can be achieved. Products containing tyrosine are said to increase melanin formation, but they require UV exposure. Also, this claim is not backed by scientific data. After consumption of canthaxanthin, it gets deposited all over the body and consequently also in the layer of fat below the skin. This gives the skin an orange-brown hue. Melanotan also requires UV exposure to be effective. Bronzers create a tan that can be easily removed with soap and water.
- Wash the skin well before applying the sunless tanning product.
- Choose a product that is best suited to your skin tone.
- Apply the product evenly and lightly. Less product must be applied on dry or thickened skin like knees, ankles and elbows.
- Wash hands with soap and water thereby avoiding coloring of the hands. Use a cotton ball to apply the product to the top of the hands.
- Wait for 15 to 20 minutes till it dries.
- DHA or Erythrulose may lead to contact dermatitis.
- Canthaxanthin may result in hepatitis and canthaxanthin retinopathy in which yellow deposits are formed in the retina of the eye.
- Bronzers have less sweat or light water resistance. They lead to some rub-off on tight clothes.
Both these types of tanning have their own benefits and hazards. In case of any doubt, make sure to contact a physician and find the right way to go about it.
Disclaimer: This article is for informative purpose only and does not in any way attempt to replace the diagnosis of a medical professional.