Why do we tan or burn?
- shelleyperezrubio
- 6 hours ago
- 3 min read
Imagine you're outside. The sun is glistening, sending waves of heat across your skin. You feel the warmth slowly soaking in. Later, you go inside and begin washing your hands under cool running water. As you look down, you suddenly notice something -- your skin has darkened. You've tanned.
Now imagine a different scenario.
You're outside again, hearing birds chirping and feeling the sunlight on your skin. Hours later, you check your arms expecting to see a tan. Instead, your skin has turned red. Just a few hours ago, you were pale, but now you’re visibly burned.
So why do some people burn while others tan?
The answer lies in melanin, the pigment responsible for the color of our skin, hair, and eyes. Melanin is produced inside tiny structures called melanosomes, which are found in specialized skin cells known as melanocytes.
Melanin plays an important protective role in the body. It absorbs ultraviolet (UV) radiation from the sun and helps protect the DNA inside skin cells from damage. People who naturally produce more melanin have more protection against UV radiation, which is why they tend to tan rather than burn.
However, this protection also affects how the body produces vitamin D.
Sunlight triggers a chemical reaction in the skin that allows the body to produce vitamin D, which is essential for absorbing calcium and maintaining strong bones.
You can think of the process like this:
Sunlight → Skin → Vitamin D production
Because melanin blocks some UV radiation, people with higher levels of melanin may need more sunlight exposure to produce the same amount of vitamin D as someone with less melanin.
Types of Melanin
There are two main types of melanin in the skin:
Pheomelanin – gives skin and hair a pink or reddish tone and is often found in people with lighter skin.
Eumelanin – produces brown or black pigmentation and provides stronger protection against UV radiation.
Pros and Cons of Sun Exposure
Sunlight has both benefits and risks.
Pros
Helps the body produce vitamin D
Supports bone health and calcium absorption
Cons
Can damage DNA and proteins in skin cells
Can cause sunburn
Increases the risk of skin cancer with excessive exposure
Tan vs. Burn
A tan happens when the skin produces more melanin to protect itself from ultraviolet radiation. The extra melanin acts like a natural shield for the skin.
A sunburn, however, occurs when UV radiation damages skin cells faster than the body can protect itself. This damage triggers inflammation, which is why the skin turns red, painful, and irritated.
Protecting Your Skin
Because ultraviolet radiation can damage skin over time, protecting your skin is extremely important. Wearing sunscreen, hats, and protective clothing can help reduce UV exposure and prevent burns.
When applying sunscreen, don’t forget areas that people often miss, like:
the back of the ears
the neck
the hands
the face
the legs
The Layers of the Skin
Our skin has three main layers:
Epidermis – the outer protective barrier of the skin where melanocytes are located.
Dermis – contains blood vessels, nerves, sweat glands, and hair follicles.
Hypodermis – the deepest layer, made mostly of fat cells that provide insulation and cushioning.
Together, these layers protect the body and help regulate temperature, sensation, and energy storage.
Works Cited:
Anastasiou, C. J. “The Sun & Our Skin: An Update for Biology Teachers.” The American Biology Teacher, vol. 53, no. 3, 1991, pp. 137–45. JSTOR, https://doi.org/10.2307/4449247. Accessed 5 Apr. 2026.
Walters, Jeffrey J., and Cynthia Szymanski Sunal. “Studying Our Skin.” Science and Children, vol. 37, no. 3, 1999, pp. 36–54. JSTOR, http://www.jstor.org/stable/43170964. Accessed 5 Apr. 2026.
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