Last reviewed 01/2018

Tanning is the darkening of the skin's colour as a result of deliberate ultraviolet radiation exposure - sunbathing. It is potent way of externally modifying the rate of melanogenesis within the skin. There may be three mechanisms at work:

  • photo-oxidation of existing melanin by long-wave UVA which lasts for less than an hour
  • production of new melanocytes, tyrosinase and melanin by exposure to UVB. There is a latency of at least 24 hours for this reaction.
  • putative oxidation of glutathione, so preventing its inhibition of tyrosinase