Despite the fact that the ancients recognized that sunlight had a. beneficial action on rickets as well as on a large number of other diseases, it appears that the year 1890 should be considered as the beginning of the modern application of light as a therapeutic measure for rickets. It was then that Palm reported his study on the geographic distribution and etiology of rickets, suggesting that sunlight should be considered a therapeutic agent. Buchholz (1904) used the "glühlicht" for treating sixteen cases of rickets. He attributed the beneficial action to the heat rays as well as to the light rays. Unfortunately, Buchholz's report never received the attention it should have had. Neumann (1909) noted that rickets occurred in a city located at an altitude of 1,560 meters, while in another at 1,740 meters where the children were allowed plenty of freedom and lived mostly outdoors, rickets was unknown.
SCHLUTZ FW. HELIOTHERAPY AND ACTINOTHERAPY IN RELATION TO PEDIATRICS. Am J Dis Child. 1927;33(1):122-135. doi:10.1001/archpedi.1927.04130130129011