How Sun Tanning Works


What Makes Your Skin Tan – An Overview

All radio stations, by law, emit radiation at their assigned frequency. If a radio station's operating frequency is, for example, 101.5 MHz (MegaHertz), then its wavelength is about 9 feet 8 inches long. The higher the frequency, the shorter the wavelength.


The sun also emits radiation, but it emits every frequency, from 0 to infinity. Within this broad range of frequencies are three narrow bandwidths which directly affect our lives: UV–A, UV–B, and visible light (UV stands for "ultraviolet" and are invisible to the human eye). Visit: www.skincancer.org/shining–light–on–ultraviolet–radiation.


When the sun's radiation strikes your skin, its UV–A rays penetrate deep within your live skin cells. Some of these UV–A rays strike your skin's melanocytes which, in turn, release melanin. Melanin is a pinkish color when it is formed. The melanin migrates to the top of your live skin cells layer. When the sun's UV–B rays strike the melanin, the melanin oxides, turning it from pink to brown (thereby giving you a tan). You now have visible evidence of damaged skin. The darkening of your skin is your body's defence mechanism to darken itself, thereby minimizing further damage from the sun's UV–radiation. A tan is a symptom of sunlight overdose.


A suntan is the beginning of a host of skin problems. If you continue tanning, in about ten years you will have "leather skin," age spots, precancerous skin growths, and possibly skin cancer.



What Makes Your Skin Tan – The Details

The very top layer of your skin is the "epidermis," and the very top layer of your epidermis is the "Horny Layer." This layer is comprised of "dead" skin cells (where sunless–tanning lotions tan your skin).


Directly beneath your "Horny Layer" is your "Germinative Layer." This layer is comprised of "live" skin cells (where sun–tanning tans your skin).


About 5% of the cells in the Germinative Layer are special cells called "melanocytes." When UV–A rays from the sun / tanning bed strike the melanocytes, they produce melanin, the pigment ultimately responsible for tanning. The pinkish melanin travels up through the Germinative Layer and is absorbed by its outer skin cells. When UV–B rays strike the melanin, the skin oxidizes, or darkens.


TanSome Sunless Tanning Lotion - Section of Skin Cells



This darkening, or "tanning," is your skin's way of protecting itself from more sunlight! In fact, a tan is a symptom of sunlight / tanning bed overdose! The skin becomes darker to reduce the amount of sunlight that can penetrate the skin. This is Nature's way of our bodies adapting to the environment to protect itself.


When the "live" cells die, newly generated "live" skin cells push the dead skin cells to the very top of your skin's Horny Layer outer skin, and are sloughed (shed). "New–dead" cells replace "old–dead" cells daily; they also contribute to the dust you see on your furniture.


Darker skin does offer greater protection than lighter skin against sunburn and skin cancer. However, that applies only to people with naturally darker skin. Tanning, like sunburns, attacks the skin's DNA, producing genetic defects that may cause skin cancer. Remember, people with naturally dark skin get skin cancer too; they just get if less frequently.



Sun-Tanning is Fun

We all love a bright sunny day! Nothing is better than being outside soaking up some rays. When we were young, there was nothing better than to grab a blanket and towels, tanning lotion, radio, those cans of beverage, and hit the beach or pool. Sunshine lifts your mood and gives you a sense of peace. It's all so very innocent, and so much fun. In 20 minutes, you'll be feeling the sun baking your skin. Keep sun tanning and in just a few years your skin will look like a worn–out piece of leather luggage!


Like fire, sunlight can be your best friend, or your worst enemy. You absolutely need sunlight for myriad reasons, but too much sun or too much tanning bed is like throwing molten tar balls at your skin Determine Your Skin Type. Your suntan sure looks great now, but you'll pay the penalty later, and you won't like what you get! (A friend of ours had the most naturally beautiful complexion of anyone. She always kept a dark, golden tan. Today, at age 50, her skin looks like a very old piece of Samsonite leather luggage!)



Sun-Tanning is Dangerous

The dangers that sunlight can inflict upon you are real and certain. Mild overexposure to sunlight will cause freckles to become more noticeable and age spots to appear from nowhere. Heavy overexposure to sunlight can cause the onset of a host of skin problems, including but not limited to: age spots, first–degree and second–degree skin burns, thinner skin, easier bruising, fine and coarse wrinkles, skin tearing, telangiectasia (varicose veins), skin lesions, and skin cancer (squamous cell carcinoma and/or basal cell carcinoma).



UV–Radiation from Our Sun

From our sun, we get radiation with wavelengths from zero to infinity. The vast preponderance of these wavelengths are not harmful, and are either absorbed by our Earth's atmosphere, or simply pass right through our bodies. Only a few wavelengths are harmful to our bodies (mostly our skin), and these are called "UV" or ultraviolet wavelengths.


A very narrow bandwidth of these wavelengths can cause us great harm. These wavelengths are called UV–A and UV–B wavelengths. Wavelengths shorter than UV–B (like UV–C and shorter) are absorbed by our atmosphere and do not reach Earth's surface (technically, radio waves, microwaves, etc reach the surface, but their power is so low they do us no harm). UV–A accounts for 95% of all the sun's UV–radiation that reaches Earth's surface.


UV–A rays are delivered to Earth's surface anytime during daylight hours. They penetrate clouds easily, causing deep skin cell damage.


UV–B rays cannot penetrate the clouds, and the amount delivered to Earth's surface is dependent upon location (increases as you travel towards the equator) and season (highest intensity on the first day of summer, and lowest intensity on the first day of winter). UV–B is delivered primarily at noon (Standard Time) plus or minus 2 hours (remember to account for Daylight Saving Time).


UV–A rays worsens the cancer–causing effects of UV–B rays, and is the main wavelength behind photoaging. Recently, an Australian–US study found that UV–A rays are more carcinogenic than UV–B rays. They penetrate more deeply and cause more genetic damage in the skin cells (keratinocytes) where most skin cancers arise. The Environmental Protection Agency, National Institutes of Health, and the World Health Organization designate both UV–A rays and UV–B rays as causes of cancer. In the graph below are shown wavelengths of Visible, UV–A, and UV–B wavelengths.


(1 nm = one billionth of a meter; a typical hair diameter is about 80,000 nm)



TanSome Sunless Tanning Lotion - Wavelength Spectrum


Visible Light from Our Sun

The visible wavelength spectrum, which we see with our eyes, ranges from red to violet. All colors we see lie between these two colors. Scientists predict we can distinguish nearly ten million different colors between red and violet. Wavelengths longer than red are called "infrared" and do us no harm, irrespective of their length. In fact, "infrared" radiation is especially needed since this wavelength warms the Earth.


Remember, visible light does not harm your skin! Actually, you need 60 minutes of 2,500 lumen of full–spectrum direct or indirect light daily for prevention of Seasonally Affective Disorder (SAD), a form of depression (Importance of Visible Light).


Only UV–A and UV–B radiation harm your skin.



UV–Radiation from Tanning Beds

Tanning beds provide primarily violet visible light, UV–A, and UV–B wavelengths. Of the radiation they provide to your body during tanning, about 90% is UV–A.


Tanning beds can deliver 12 times more UV–A radiation than the sun. Recent research is showing that UV–A radiation is far more dangerous than UV–B radiation because it penetrates the skin deeper. UV–A radiation is known to cause photoaging, skin lesions, skin cancers, and a host of other skin problems.