Sunbed. Teenage boy under an ultraviolet light sunbed. He has pieces of metal over his eyes to protect them from the radiation. Sunbeds are designed to give the skin doses of ultraviolet (UV) light to promote the formation of a suntan. Modern sunbeds use longer-wavelength UVA light (at a wavelength of around 320-380 nm). Most of the damage associated with sunbathing and sunburn is caused by UVB light (around 280-320 nm). Suntans are formed due to the increased production of a pigment called melanin, which protects the skin from over-exposure to UV radiation.