How was Niels Ryberg Finsen awarded the Nobel Prize in Physiology or Medicine?

Name: Niels Ryberg Finsen.
Country: Denmark, Faroe Islands.
Date of Birth: 15 December 1860.
Died: 24 September 1904.
Education: University of Copenhagen.
Subjects Of Study: Disease phototherapy Skin.
Known as: Phototherapy.
Noble Prize Year: Nobel Prize for Peace in 1903, for his recognition of his contribution to the treatment of diseases, especially lupus vulgaris, with concentrated light radiation.