Radiation from the sun contains invisible ultraviolet (UV) radiation. UV radiation causes damage to the skin that, in the long term, can lead to skin cancers.
Skin cancer is the most frequent cancer worldwide in predominately fair-skinned populations, and its occurrence has dramatically increased over the past few decades. There are different types of skin cancer. Melanoma (the so-called “black skin cancer”) originates from pigment-producing cells, and although it is the least common type, it is the most aggressive one, with poor prognosis if detected late. There are two main types of non-melanoma skin cancer: basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) (“white skin cancer”). BCC is the most frequent cancer in fair-skinned populations worldwide. BCC only very rarely spreads (metastasizes) but may occur at exposed body sites, such as the face. SCC is less common but may be fatal once the cancer has spread before it is detected. Exposure to UV radiation has many negative effects on your skin, of which the most immediate ones are tanning or burning.
Reference. ECAC website: cancer-code-europe.iarc.fr
Sunbeds are machines designed to emit ultraviolet (UV) radiation. This UV radiation has the same damaging effects on your skin as natural sunlight and, as it is unnecessary exposure, should be avoided at all times. Tanning on a sunbed does not provide a better base for later additional tanning in the sun, and there is no such thing as a safe tan.
The use of sunbeds to increase your vitamin D level is unnecessary and is strongly discouraged. The same type of UV radiation induces a suntan as also increases your risk of skin cancer and damages your skin in the ways described earlier. Some people consider that their use of sunbeds helps to treat winter depression, but this can be done more safely by using bright visible-light lamps that do not emit UV radiation. People who require medical UV treatment for a disease should be treated under close medical supervision, for instance in clinical settings. Sunbeds are sometimes marketed to treat a variety of complaints and diseases (e.g., neurodermatitis, acne, high blood pressure) or to improve immune responses. Any use for medical reasons should, however, be prescribed and supervised by a physician.