Seasonal Hair Growth and Hair Loss
Prof. Dr. Murat Türkoğlu
The hair growth and fall cycle is called "anagen-telogen". At least 80-85% of the hair on the head of people is in the growth phase. There is a rate of 15% in the resting and fall phases. However, dermatological diseases, hormonal disorders and some drugs may change these rates. Hair may have different growth-fall rates according to the seasons of the year. This is what we call seasonal hair loss. It is observed that during autumn months hair is in the telogen phase with a slower growth and a higher percentage, and during spring and early summer, there is an increase of hair in the anagen phase.
The months when hair is in the fastest growing period are between March and June. Follicles are in the period of rest and fall (Telogen) at a higher rate in the October-December period. This seasonal change observed in hair and beard can be related to the decreasing metabolic rate in winter. Why does metabolic rate decrease? There may be two different reasons for this. Until modern times, human societies had to survive with a very limited diet in winter, except in the tropic areas. Apart from the grains, vegetables, fruits and canned foods they obtain in the summer, there are quite insufficient conditions in terms of protein, vitamins and minerals in the winter period. The human body may be slowing down its metabolism during the winter months in order to adapt to this situation. Another factor is the lengthening of the nights and the shortening of the days during the winter in the northern hemisphere. Less use of sunlight slows down the metabolism and promotes the rest cycle. When these two factors are considered, there is a slow growth in hair and beard. Today, in modern life, there is no shortage of food during the winter months, but still the short days and longer nights have an effect on the metabolism.