Sunlight: find out how it affects our skin


Dr. Laura Miguel - Dermatologist. Hospital Ramón y Cajal

Sunlight is essential for our organism to function correctly, we can’t live without it. However, it’s important to remember that prolonged exposure to the sun builds up over the years and without the right sun protection, the skin can suffer damage and this in turn can lead to tumours like melanoma.

What is sunlight and how does it affect our skin?

Sunlight is the energy emitted by the sun in the form of electromagnetic radiation. This radiation can have different wavelengths:

Radiation emitted by the sun

WAVELENGTH (Nanometres)

Infrared light

700 nm-1 mm

Visible light

400-700 nm

Ultraviolet (UV)

UVA   315-400 nm

UVB   280-315 nm

UVC  100-280 nm

UVC radiation is the most harmful for humans, however, it does not reach our planet because it is absorbed in the atmosphere. A minimal amount of UVB rays reaches us and can cause damage to the skin’s surface like premature aging (wrinkles, blemishes), skin cancer (they affect cell DNA and cause mutations), photosensitive diseases, eye damage, etc. The best way to prevent these harmful effects is to use the right sun protection.

Characteristics of UV rays and sun protection against UVA and UVB rays. 

UVA rays

UVB rays

Same intensity throughout the day

More powerful in the middle of the day

Same radiation even on cloudy days

More harmful in summer and at high altitude

Penetrate the deepest layers, affecting the dermis

Do not penetrate as deeply but they cause oxygen free radicals that are harmful for the different layers of the skin

Boost tanning

Responsible for reddening and sunburn

They can pass through clothes and windows

They can pass through clothes and windows

Affect the DNA due to free radicals forming

DNA mutations


To achieve a good level of protection against the harmful effects of the UV radiation emitted by the sun we need to avoid prolonged exposure in the middle of the day (from 12h to 17h) as this is when the UVB rays, in particular, are at their strongest; choose a sun cream with a high sun protection factor (at least SPF +50); reapply the cream at least every 2 hours and always after going in the water and above all, wear appropriate clothing that protects the skin and eyes (caps, hat, t-shirts, approved sunglasses).

To sum up… the sun has enormous benefits for our body, but, we need to be aware of the risks of prolonged exposure and not protecting the skin correctly.


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Dr. Laura Miguel Gómez. Dermatologist. Hospital Ramón y Cajal


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