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Science of Sunless Tanner: How Does it Work?

Wondering how sunless tanners work? We can explain. Here's the science behind sunless tanners

Learn how sunless tanners really work

While a beach-bronzed tan may give your skin a glow that we interpret as a look of health and beauty, it’s actually a sign of your skin’s reaction to damage. Darkened skin is the body’s way of responding to UV ray exposure in a way that tries to protect it from further harm. Exposure to the sun’s UV rays stimulates the protective response in our skin to produce melanocytes in a combination of brown, yellow and red pigments that help the cell’s to help absorb the radiation in the sun’s rays. The amounts and colors of the pigments produced vary with different people and ethnicities, depending on the amounts of melanocytes that their skin is able to produce. This is why some people turn a deep golden color, and others may turn pink or red and simply burn.

Throughout most of human history, caucasian people saw pale, untanned skin as a sign of beauty because it indicated that a person was wealthy and successful enough to not have to toil outdoors in the sun. Eventually however, a tan began to be associated with fun, sporty, outdoor activities and became a sign that one had the leisure time to pursue vigorous outdoor recreation. Some attribute this trend partly to fashion icon Coco Chanel, whose return from a yachting trip to be photographed looking fit and tanned, sparked a new trend. As a result a suntan, at least in summer time, became the popular look.

Unfortunately, by the 1970’s it had become clear that tanning was linked not only to premature lines, wrinkles, and sunspots, but also to skin cancer, including deadly melanoma. People began to seek sun protection, but were reluctant to give up the look of sun-kissed skin. Eventually, the science of sunless tanning began, and lines of new sunless tanning products were developed to give the skin a tanned appearance that did not involve UV exposure.

Sunless Tanning? How we Tan our Skin Without the Sun

In the 1950’s a medical researcher noticed that a medication she was testing was changing the skin color of her patients, while not staining their clothes. She soon pinpointed the ingredient, dihydroxyacetone (DHA), in the medication that was responsible for the darkening of the outer layer of skin. That ingredient would go on to later spark a new industry, the industry of self-tanning. But what is DHA and how does it work?

Dihydroxyacetone is a 3-carbon sugar that comes from sugar beets and the fermentation of glycerin. When applied to the skin, DHA binds with the top layer of cells, the dead skin cells of the skin’s outer layer. These dead cells are missing their nucleus and organelles and can no longer reproduce, but they still contain keratin, the amino acid that is responsible for skin color. When DHA combines with these amino acids, it triggers a reaction that produces red, brown, and yellow pigments, causing a darkening, or browning effect known as the Maillard reaction. This is the same reaction that causes natural sugars in foods to achieve the caramelization, or browning effect when heated.

Another, less fortunate, side effect of the DHA chemical reaction on skin cells is the release of a strong odor. This is why sunless tanners smell unpleasant on the skin while working their magic.

Why is the Color of a Sunless Tan a Little Different Than a Natural Tan?

The pigments produced by a sunless tanner are caused by melanoidins rather than the melanocytes produced by UV rays, so the pigments are not exactly the same. Melanoidins tend to produce more yellow and less red pigments, which results in a more orange-toned tan than a naturally caused tan.

Thankfully, industry experts have worked hard in recent years to improve the original sunless tanning formulas to produce less orangey results, and a more natural-appearing tan, as well as to prevent streaking and improve or better mask the scent.

Why Doesn’t a Sunless Tan Last?

Because the DHA reaction involves dead skin cells, the color slowly fades away as the dead skin cells are sloughed off. For this reason a sunless tan will only last three to five days, unless the tanner is reapplied. Excessive scrubbing, washing, sweating, or water submersion will cause a sunless tan to disappear faster.

While a sunless tan is not perfect because the color may be hard to get exactly right, the odor can be masked but still unpleasant, and the longevity doesn’t match that of a real tan, improvements are being made all the time. Sunless tanning is a much safer alternative than sunbathing in order to achieve a tawny summer look that will not damage your skin.

Resources — Scientific American, HowStuffWorks, Synapse, Fashionista

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