The finsen light, named for its inventor, Niels Tyberg Finsen, was a powerfullight used to cure people of a skin disorder. Niels Finsen was born in 1860in the Faroe Islands, Danish islands in the North Atlantic Ocean. His parentswere of Icelandic origin, so young Niels spent his early schooling in the capital of Iceland. He was a frail and sickly youth. Living so close to the Arctic Circle where the days are short in winter, Niels became aware of the effects of sunlight on his disposition and health. Later Finsen went to Denmark to study for his medical degree at the University of Copenhagen. While at theuniversity he was incorrectly diagnosed as having heart disease, but actuallyhe suffered from Pick's disease, a condition that affects the liver and thelining around the heart. (He later developed ascites, fluid accumulation in the abdominal cavity, and was confined to a wheelchair.) After receiving his medical degree in 1891, Finsen became very interested in how light affects disease as he himself found a benefit from exposure to sunlight. He was familiarwith the work of a Swedish researcher who in 1889 had discovered that ultraviolet light (short waves) irritates biological tissue more than infrared light (longer waves such as heat waves). So Finsen began recording the effects ofsunlight on insects and amphibians, becoming ever convinced that light couldbe used to treat human disease. He found that ultraviolet light from the sunor from electric lights could kill bacteria. Finsen was convinced that it was the effect of the light and not the heat it caused and wrote several papersin 1893 and 1894 on the beneficial use of phototherapy. He also thought thatred light was helpful in curing smallpox but this idea was later abandoned. In 1895 Finsen made an arrangement with Copenhagen Electric Light Works to treat patients two hours each day with ultraviolet light. His patients were diagnosed with lupus vulgaris, a skin disease associated with the tuberculosis bacteria. He designed a powerful lamp (the finsen light) for this purpose, a bright artificial light generated by electrical carbon arcs. In1896 Finsen founded the Finsen Institute for Phototherapy in Copenhagen dedicated to studying effects of light and curing people of disease. At the Institute 800 lupus patients were treated. Half were cured of the disease and nearly the rest showed improvement in their conditions. For this achievement he was awarded the 1903 Nobel Prize in medicine and physiology. Finsen donated half the prize money to the Institute. In failing health, he died the next yearat only 43 years old. During Finsen's era both X rays and gamma rays were discovered by Wilhelm Röntgen (1845-1923) and Antoine-Henri Becquerel (1852-1908) respectively. With Finsen's success with light therapy leading the way, the idea of radiotherapy was born. Since his time, X rays andgamma rays have been used for the diagnoses and treatment of disease. Even today some foods are irradiated with UV light to kill bacteria (although thispractice is sometimes controversial). Finsen was also ahead of his time in his concept of the effect of sunlight on disposition and health. It is only fairly recently that Seasonal Affective Disorder (SAD) has been recognized as a type of depression caused by a lack of sunlight in winter. People diagnosed with SAD can be treated by sitting under lights to extend exposure to light on short days.