Seasonality of Hair Loss
Many people, especially women, complain about increased, seasonally-determined hair loss. This applies to women who suffer from female hair loss as well as those who don't. A recent study tried to determine whether there was any truth behind such claims. The study was conducted over a period of six years with subjects that were not suffering from any clinically proven form of hair loss, though all of them complained about seasonally recurring shedding. Subjects taking medications, which could cause increased hair loss, were also excluded from this study. 823 women participated.
Analysis of trichograms clearly showed regular periodicity in hair growth and shedding during the year. The maximum percentage of hairs in the telogen (resting phase) was registered in summer, with early spring showing a second peak. The lowest percentage of hairs in the resting phase - and, therefore, the highest hair density - occurred in late winter. This confirms the results of earlier studies that annual periodicity in hair growth and shedding exists; but this was the first systematic, large scale study.
Seasonality of Hair Shedding in Healthy Women Complaining of Hair Loss, Michael Kunz, Burkhardt Seifert, Ralph M. Trüeb