A tanning device is described by which the bluish light emitted by mercury vapor lamps is converted into yellow or white light. For this purpose, the mercury lamps, or the sheets of transparent plastics material covering these lamps, are doped or coated with one or more organic or inorganic fluorescent dyes that partially absorb the blue light emitted by the mercury lamps and convert it into light of wavelengths of 550 to 650 nm.