How do sunbeds produce a tan?
Sunbeds mainly emit UVA radiation which activates the melanin pigment already embedded in the upper skin cells. This immediate tan begins to fade within a few hours after cessation of exposure, but can persist following sufficient and repeated exposure. The small amounts of UVB emitted by sunbeds induce the so-called delayed tanning reaction, where new melanin is produced and distributed between the upper skin cells.
Increasing numbers of people rely on sunbeds for whole-body tanning and to tan beyond their normal complexion. This forced tanning is associated with DNA damage in melanocytes, the cells that produce the dark-coloured melanin pigment in the skin. In genetically dark-skinned individuals, relatively little DNA damage is sufficient to bring about the extra-tanning effect. In contrast forced tanning in fair-skinned individuals is associated with a lot of DNA damage. It is mainly fair-skinned people who are keen to darken their complexion.
Sunbeds are not as successful in producing a tan as the people using them would like them to be. A recent British survey reported that only 2/3 of the regular sunbed users interviewed had achieved moderate tanning, while 1/3 had gained a mild tan; some also reported patchy tanning.