The Influence of Light on the Growth of Hair, and Its Therapeutic Use in Alopecia Areata. By Dr. Schmidt, Assistant at Dr. Lesser's Clinic in Berlin. Archiv. f¨ur Dermatologie und Syph., Oct. 1902.
It has been proved that the hair of the head and the beard, as well as the nails, grows more quickly in the warm periods of the year than in the cold.
J Cutan Dis. 1903;21:51-52.
Despite the bald assertion of proof, a seasonal variation in human hair growth has been debated for years. Trotter1 saw no evidence of such, though Orentreich2 found short-term variations superimposed on longer seasonal cycles. Studies conducted by Randall and Ebling3 in England did find cyclical changes in anagen hair counts, which they suggested were a vestigial analogy to the spring and autumn molt of mammals living in temperate regions. What other dermatologic atavisms might there be?
ABSTRACTS.. Arch Dermatol. 2003;139(1):13. doi:10.1001/archderm.139.1.13