Faroese physician, who got the 1903 Noble prize for the invention of light therapy.
Finsen was the second of the ten children of the jurist and Danish administrator Hannes Christian Steingrim Finsen (3 May 1828, Reykjavik – 18 Nov 1892, Ribe), who married twice. He belonged to an old Icelandic family with traditions reaching back to the 10th century. On 12 May 1858 Hannes married Finsen’s mother Johanne Sophie Caroline Christine Formann (12 Augustus 1833, Copenhagen – 10 May 1864, Torshavn, Faeroe) and got four children. She died when Niels was three years old. On 5 October 1865 he married his mothers cousin Birgitte Kirstine Formann (13 Aug 1840, Dronninglund – 7 July 1930, Esbjerg) with whom he got six children.
Finsen studied in the secondary school of Tórshavn, but Summer 1874 he was sent to the Danish boarding school Herlufsholm, where his older brother Olaf Finsen (3 Feb 1859 – 1937) was also a student from 1873 until Christmas 1875 . Olaf became a pharmacist in 1883. The brothers corresponded a lot and some 172 letters were preserved. The philologist Johannes Forchhammer(1827-1909) was rector at Herlufsholm. He had twelve children. His son Holger Forchhammer (21 October 1866, Aalborg – 19 May 1946, Copenhagen), a medical consultant, would become Finsen’s closest associate and friend.
In January 1876 Niels was one of the best students of the boarding school, but Rector Forchhammer stated: “Niels Finsen is a good-hearted boy, but the skill is small, and it lacks quite the energy.” It was decided (Early July 1876) that Niels would leave school (11 Aug 1876) and continue his schooling at the Grammar School in Reykjavik, where Niels’s grandmother, the 40 years widowed Marie Nicoline Finsen, would care for him (October 1876). On 18 July 1882, Niels graduated at age 21 from Reykjavik’s Grammar School, having the best results in mathematics and natural science. He studied medicine from autumn 1882 to summer 1890 in Copenhagen, where he met again Holger Forchhammer.
After his graduation, summer 1890, he became a prosector of anatomy at the university of Copenhagen. In 1893 he devoted himself fully to his scientific studies on light. In 1898 he became a professor of light therapy and in 1899 he became a Knight of the Order of Dannebrog.
As a medical student in Copenhagen, Finsen did since 1887, simple, but cardinal personal observations on animal behaviour with regard to the sun light. He noticed that a cat moved away from the shadow and into the sunshine, even if the shadow temperature was pleasant. At the bridge of Christiansborg, he observed that insects that ran on the water surface, when they approached the bridge’s shadow via the stream, quickly moved back to the area illuminated by the sun. He gradually came to the insight that sunlight may have a positive biological effect in the struggle for the survival of the fittest .
Later he became aware of the study of ultraviolet (UV) light pioneers Downes and Thomas Porter Blunt, who demonstrated that sunlight could kill and inhibit the development of pathogenic bacteria (Nature, 12 July 1877). In time it was discovered that the invisible energy-rich violet and ultraviolet parts of the sun light were biochemically seen the most active particles of the sun light.
Our eyes can not see the ultraviolet “black light”, as it’s biological activity would destroy our light sensitive retinae: We would be blinded by the light. For this reason, the high energy “black” light UV radiation, is filtered or neutralised by the outside parts of our eye-lens, before it reaches the light sensitive retina. But in this the UV light neutralising process, the eye lens in time gets “troubled”: It leads to the in elderly seen disease of “Staar” or cataract. In the animal world, only the short lived worker bees, are known to see the UV light (and more). They use it to detect the flowers and thus by them needed nectar. Today, artificial UV light is used on a industrial scale to conserve perishable food like meat, fish and vegetables.
With his knowledge of nature Finsen performed numerous experiments to find out how to most effectively kill bacteria using light. He published “Om Lysets Indvirkninger paa Huden” (On the effects of light on the skin) in 1893 and “Om Anvendelse i Medicinen af koncentrerede kemiske Lysstraaler” (The use of concentrated chemical light rays in medicine) in 1896. In his later work, when he suffered from ascites and edema because of heart disease, he researched the effects of a low sodium diet and published “En Ophobning af Salt i Organismen” (An accumulation of salt in the organism) in 1904.
After an experimental with hopeful results in individual cases stage, Finsen started 12 august 1896 with the aid of the Copenhagen administration, a clinic for the light treatment of patients in Copenhagen. The Finsen Institute later moved to the University of Copenhagen. It now specialises in cancer research using protelysis.
Finsen suffered from the acquired Pick disease (not the hereditary Nieman-Pieck disease) or constrictive pericarditis, in which there is an harness of fibrotic tissue (scarring) around the heart. He was wheel-chaired as a lecturer. In 1898 his health was to weak to give lectures abroad. His friend and colleague Forchhammer represented him on the international congress of physicians Paris (1890).
In 1903 Finsen was awarded the Nobel Prize in Medicine and Physiology “in recognition of his contribution to the treatment of diseases, especially lupus vulgaris, with concentrated light radiation, whereby he has opened a new avenue for medical science.” The Noble Prize Committee was aware of his deteriorating health.
Personal
On 29 December 1892 at Ribe, Finsen married the 24 years old Ingeborg Dorthea Balslev (3 Augustus 1868, Ribe – 30 July 1963, Frederiksberg). They got four children: Gunnar (1895-1895), Halldor (1896-1987), Gudrun (1900-1948) and Valgerda (1903-1998).
He died 24 September 1904, Copenhagen of the disease, 9 months after receiving the Noble Prize of heart failure.

Link to Wikipedia