Medicine: 1903

Finsen, Niels Ryberg (1860-1904), a Danish doctor and scientist, was the founder of phototherapy (the treatment of disease by the influence of light). He received the Nobel Prize for physiology or medicine in 1903 for his discoveries in the treatment of many skin diseases, including lupus vulgaris (a type of tuberculosis that affects the skin).

Finsen experimented with different concentrations of light rays and demonstrated their beneficial effects on the skin. He also showed that if the irradiation of the light is too concentrated, it can cause harmful effects, resulting in damage to the tissue. This damage can be reduced by the amount of melanin (pigmentation) in the skin.

Finsen was born at Thorshavn, in the Faroe Islands. He studied medicine at the University of Copenhagen from1882 to 1890. Finsen's health started to fail when he was in his 20's. He suffered from constrictive pericarditis, a condition causing inflammation of the pericardium, the membranous sac enclosing the heart. His doctors believed that sunlight would have a healing effect. In a description of his work, Finsen said, "The disease was responsible for my starting investigations on light." In 1896, he founded an institute for the study of phototherapy called the Finsen Ray Institute in Copenhagen. He was director of this institute from 1896 to 1904. He gained the title of professor in 1898.