The most popular method of sunless tanning is through products you apply on your skin, such as creams, lotions, foams, gels and sprays, which turn our skin from pasty white to a crisp tan. But, there are also tanning pills and sunless tanning mist that can be professionally applied at a salon through a machine or even an airbrush artist.

But how do these products work: The human skin is made up of two main layers, the inner, or dermis and outer, or epidermis. When it comes to tanning, the layer we are most interested in is the epidermis. The epidermis has two layers, the stratum basale and the stratum corneum. The deeper layer is the stratum basale, and that is the layer that is affected by tanning in the sun. The outer epidermis is the stratum corneum. This is the layer where the sunless tanning products react. So, in general the outermost layer gets dyed temporality. But, each tanning product works slightly different.

According to the American Academy of Dermatology, the most effective sunless tanning products are ones containing the chemical dihydroxyacetone, better known as DHA. DHA is a colorless sugar, and as it interacts with the dead cells in the stratum corneum, a color change occurs. Color resulting from the DHA ingredient lasts about five to seven days. DHA can be found in sunless tanning lotions, creams, gels and sprays. Check product labels to see if the product contains DHA.

DHA is also found in the formulas used in sunless tanning booths. When the customer follows the directions properly, these sunless tanning booths can produce an instantly flawless tan. These tanning booths are equipped with an air brush delivery system that sprays on a tanning solution comprised of DHA and bronzers. So, the bronzers give an instant color and the tanning solution with DHA gives a deeper color that allows this instant tan to last up to a week.

More about bronzers: Bronzers can come as powders and moisturizers, and are often also combined with other self-tanning methods. A bronzer applied alone creates a tan that can easily be removed with soap and water. Bronzers work more like a make-up, tinting the skin temporarily. However, as noted, other self-tanning products can contain bronzers to give an instant color, while the other chemicals take longer to appear. So, a bronzer can act alone or help out with a fellow sunless tanning lotion.

Another ingredient found in self-tanners is the amino acid tyrosine. Makers of these products claim that tyrosine increases melanin formation in the skin, which then accelerates the tanning process. In fact, you may have heard these products referred to as tanning accelerators. This ingredient is usually found in sunless tanning pills or lotions.

Finally, sunless tanning pills work through a chemical usually used to add color to foods: canthaxanthin. When it comes to self-tanners, canthaxanthin is most commonly found in tanning pills. Once the canthaxanthin is consumed, the chemical is deposited throughout the body, including the skin, resulting in an orange-brown color. These canthaxanthin-containing pills also work to accelerate a suntan. The FDA has not approved this as a tanning agent, however.

Going back to the layers of skin, it is important to understand that millions of dead skin cells leave the body every day. This is why our tans disappear. Since sunless tanning products work on the outermost layer of skin, the color will dissipate in less time than a regular suntan. We actually have a new epidermis every month or so! So, if sunless tanning is the only method of tanning you are using, it is important to maintain the tan by using your specific product every few days.