Melalui proses yang dikenali sebagai melanogenesis, sel-sel melanosit akan menghasilkan melanin, iaitu sejenis pigmen yang boleh dijumpai di bawah kulit, mata dan rambut. Melanogenesis ini menyebabkan keperangan kulit yang berkekalan berbeza dengan keperangan yang berasal dari pengoksidaan melanin yang telah wujud.[6]

There are both basal and activated levels of melanogenesis; lighter-skinned people generally have low basal levels of melanogenesis. Exposure to UV-B radiation causes an increased melanogenesis as a response to DNA photodamage.[7]

Since the action spectrum of sunburn and melanogenesis are virtually identical, it is assumed that they are induced by the same mechanism.[8] The agreement of the action spectrum with the absorption spectrum of DNA points towards the formation of cyclobutane pyrimidine dimers (direct DNA damage). The acronym for cyclobutane pyrimidine dimers is CPDs.