The skin and sun exposure

The skin

The skin does a lot of important things:

  • It keeps everything inside the body.
  • It protects your insides from infections and injury.
  • It helps keep your body temperature normal.
  • It lets you feel things by touch.

The skin has two layers:

  • Epidermis. This is the top (surface) layer of skin. It is tough and waterproof. Epidermis cells are constantly being rubbed off and replaced.
  • Dermis. Nerves, blood vessels, sweat glands and hair roots are in this layer.

Below the skin is a layer of fat.

The structure of the skin
The structure of the skin

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Melanocytes are cells in the skin that make melanin. Melanin gives the skin its colour. It also protects skin from being harmed by the sun.

When our skin comes into contact with sunlight, the melanocytes make more melanin. The extra melanin absorbs more ultraviolet (UV) rays. It also makes the skin darker, making it look suntanned. A suntan is a sign that the skin is trying to protect itself.

People with naturally dark (brown or black) skin have the same number of melanocytes as people with white skin. But people with darker skin make more melanin. This means they have more natural protection from the sun’s UV rays.

Moles are made from close groups of melanocytes. Most people with white skin have about 10 to 50 moles on their skin. Some people can have as many as 100, which can increase the risk of getting melanoma.

Vitamin D

It is important to be careful about how much sun you are exposed to. But you also need some sunlight to make enough vitamin D to keep your bones and teeth healthy.

It is usually easy for people who have never had melanoma to get enough sun exposure. In the UK, this means going outside regularly (without sunscreen) for 10 to 15 minutes around midday. The amount of sun exposure you need to build up enough vitamin D depends on your hair and skin type. Darker skin types need more sun exposure. But you should not stay out long enough to let your skin redden or burn.

If you have (or already had) melanoma, ask your skin specialist for advice on sun exposure and vitamin D.

Back to Melanoma

What is melanoma?

This section is for teenagers and young adults. It is about a type of skin cancer called melanoma.

Having tests for melanoma

If you have symptoms, your GP will examine you and decide whether to refer you to a hospital specialist for further tests.


Melanomas in young people are usually found early and cured. Surgery is the most common treatment for melanoma.

After treatment

Cancer can have a big impact on your life, even after you have finished treatment.