How does my skin tan?
Congrats! By reading this, you’re taking the first, and biggest, step to becoming a smart tanner! The skin is a crazy, complex organ, but equipping yourself with this information will leave you with the confidence of knowing you aren’t harming yourself…I promise it’s worth the read!
So here’s what you probably know: Tanning is the body’s way of protecting the skin from the sun’s rays.
What you probably don’t know: Tanning begins the very second you step into the sun. This is your body’s natural (and intended!) response to the ultraviolet light exposure. UV light is energy that travels in waves, and different waves affect different skin types in different ways.
Since the science behind the tanning process isn’t generally common knowledge, let me break it down for you. (If you’re already a science whiz, I’m jealous, and skip down to the part about skin!)
What should I know about UV light?
As mentioned, ultraviolet light is composed of energy waves. These waves are transmitted 93 million MILES from the sun to the Earth! Crazy, right!? Each wave, or light ray, is measured in nanometers (one-billionth of a meter). These varying rays are organized based on their individual wavelengths within an entire light spectrum.
There are many different types of waves (most of which are filtered out by the atmosphere), yet no two are the same. They’re categorized into three groupings: infrared light, visible light, and UV light.
Infrared Waves = waves measured above 700nm. These include electric, radio, infrared, and shortwave infrared waves (which are the only type to reach Earth, provide us with the heat we need to survive, and make up about 49% of the solar radiation we receive on Earth).
Visible Rays = waves measured between 200nm and 400nm. These rays cause illumination, which we then see as colors! These account for about 46% of the Earth’s solar radiation.
Ultraviolet Rays = waves measuring between 200nm and 400nm. These make up the remaining 4% radiation we receive on Earth. Of all of the invisible rays, just two of the UV light rays actually penetrate Earth’s atmosphere. And, you guessed it! These are the rays used in tanning beds. As UV waves are shorter in length than visible light rays, we can only see the effects of ultraviolet light, aka tanned skin!
There are 3 categories of UV rays:
- UVA rays = longest (320nm-400nm)
- UVB rays = shorter than UVA rays (290nm-320nm)
- UVC rays = shortest (200nm-290nm)
Of these, only UVA and UVB pass through our atmosphere.
Since only UVA and UVB waves cause skin to tan, these rays can be replicated in special lamps known to you as (drumroll please…) tanning bed bulbs!
Then what should I know about skin?
Skin is the largest organ in the human body. Weighing in at roughly nine pounds on the average adult, skin protects the body from harmful pollutants in the air, water, and other things you may come in contact with every single day. Not only is skin our natural armor, it also helps regulate body temperature, houses sensory receptors that allow you to feel things, and synthesizes various body chemicals necessary for living. Thus, the condition of our skin is a very important part of good health.
The skin is divided into three primary layers:
- Epidermis (the top layer): produces a tan
- Dermis (the middle layer): contains collagen, blood vessels, nerve fibers, and other elastic materials important for skin’s durability and strength
- Subcutaneous tissue (the bottom layer): composed of fat that binds the skin to the body; serves as the body’s food reserve, insulation, and shock absorber
Skin cells in the epidermis are constantly reproducing, pushing older cells up to the surface of your skin, which is sometimes called the horny layer. This is an outer mantle of dead skin cells that naturally sloughs off in about one month. The three main types of cells in the epidermis are:
- Basal cells: oblong cells that line the base of the germinative layer, aka the parent cells, giving “birth” to keratinocytes.
- Keratinocytes: “daughter” cells that serve as your skin’s sealant, making up most of your epidermis.
- About 5% of the skin cells in the epidermis are special cells called melanocytes, which lie on the bottom of the epidermis. Melanocytes are pigment cells that help the skin tan.
Melanocytes produce melanin—a protein pigment that protects skin from overexposure to UV light. The presence of melanin in the skin colors and protects it.
*Cue sparkles and confetti* Now that you have that background, let’s get into the nitty-gritty of what the tanning process actually is.
So, what is the tanning process?
Whenever UV waves touch melanocytes (tan-making cells), they produce additional melanin, causing the skin to darken. IMPORTANT: this is in order to protect the body from over-exposure! This process produces a tan—literally, a browning of the skin. As you might’ve suspected, the color of your tan depends on heredity and previous exposure to UV light, and this is why some fair-skinned tanners can get dark quicker than others.
As you may know, UV light can affect the skin in other not-so-fun ways. Over-exposure can cause sunburn (a reddening caused by the swelling or bursting of tiny blood vessels in the skin). Repeated sunburn is believed to be the greatest risk factor for long-term skin complications. This is why preventing sunburn AT ALL COSTS is THE most important thing you should do as a smart tanner.
Long story short…
Although all UV light is capable of tanning skin, UVB is more efficient at certain functions within the tanning process (think behind-the-scenes), while UVA is more efficient in showing the product of the process your skin undergoes—the tan. (For example, melanin produced when your skin is exposed to UV light is naturally pink in tone. But UV light also oxidizes the melanin, turning it brown.)
- UVB is a shorter wave that tells melanocytes in your skin to start producing melanin.
- UVA is a longer wave that oxidizes the melanin your skin has already produced, turning it brown.
Now that you have gotten a quick, yet thorough, lesson on how your skin tans, you’re that much closer to becoming a smart tanner! We at Ultimate Sun promise that it’s NOT hard to do! And, we’re always here to help.
Thanks for reading our blog, Ask Ultimate Sun! Check back next Wednesday for a fresh topic and more great info!