We do not know exactly why in the northern hemisphere people shed more hair in the fall, but it is something that many people complain about, especially in Europe. With all these self-reports of people claiming they shed more in the fall, researchers sought to investigate if the seasonality of hair loss did exist; and if yes, what is the reason behind such a phenomenon.
According to a study on 823 women without any underlying forms of alopecia, it is found that the proportion of telogen hairs tend to reach a maximum during summer, thus resulting in an additional amount of hair shedding in the following months.
Through this article, we would like to shed light on the seasonal pattern of hair loss and defuse your anxiety about this completely normal hair shedding.
The Hair Growth Cycle
As we all know, the cycle of hair growth includes four stages: anagen, catagen, telogen, and exogen.
The anagen phase or the growing stage lasts from 2 to 6 years. During this phase, hairs grow up to 100 cm in length. The second phase, catagen, lasts for only a few weeks. It is the transition stage in which metabolic activity slows down, hair follicles shrink and detach from dermal papillae.
The third phase lasting up to three months is called telogen. During this time, your hair ceases to grow and enters the resting stage. Exogen is the last stage which takes place in a few days. This stage represents the period from when a resting hair reaches its terminal position in the follicle to when it finally detaches.
The hair growth cycle would generate hair replacement every 3 to 5 years, and each hair follicle can undergo 10-30 cycles in a lifetime. At any given time in a normal healthy person’s scalp, of all hairs, 9% are in the telogen phase, 1% in the catagen phase, and 90% in the anagen phase. The telogen rates of 10% to 20% are considered normal. However, to maintain a consistent covering, the amount of hair formation needs to match the shedding amount.
Hair Loss and Seasonality of Hair Loss
Seasonal hair loss pattern is defined by differing rates of hair shed throughout different seasons. A study of 823 healthy women in Europe found that most women in the cohort had a maximal proportion of hairs in the telogen phase of the hair growth cycle during summer months (e.g., July), while the lowest telogen rates are during winter. Later on, those telogen hairs will all likely begin shedding from September to November. This finding indicates that seasonal changes generate a discernible influence on the hair growth cycle of women.
So what is the possible cause of seasonal pattern of hair loss?
According to the study “Seasonality of Hair Shedding in Healthy Women Complaining of Hair Loss", this is more likely a selective reaction of the head insulation. This body reaction will protect the scalp from the cold in winter and the heat of the midday sun during summer.
As mentioned above, to maintain a normal hair growth cycle, the amount of new hair must match the shedding amount. However, during summer and winter, to protect the scalp from potential seasonal harm (e.g., heat, cold), the telogen phase becomes longer. Therefore, more telogen hairs remain on the scalp for a longer time than usual. Then, when autumn arrives, those telogen hairs will shed altogether.
Due to this seasonality of hair loss, the number of hair strands falling is higher than usual at certain times of the year, which may cause you to misinterpret as signals of an alopecia issue. Yet it is not accurate! Seasonal hair loss is temporary and should last no longer than 4 to 6 weeks. Hair loss during such periods could happen purely because of your body's mechanism to protect your scalp from the harmful changes of the weather.
Hair Care Through Seasons
So now we all know that during late summer and autumn, your hair shedding can happen more intensely than usual. This is normal hair shedding if there are no other signs or symptoms. The hair cycle is still running, and anagen hair will soon emerge. Thus, there is no reason for you to worry or to panic.
With that said, it is crucial to protect and nurture your scalp so that your new hair will grow strongly in the anagen phase. Instead of wasting your time worrying about the quantity of hair shedding, you can pay more attention to enable the best condition for your new hair. Besides shampoo and conditioner, adding a nourishing mask or serum to your hair care routine could benefit your scalp greatly, thus enhancing hair regrowth.
However, whenever noticing a severe condition of hair loss, you should visit your dermatologists. Having your hair issue determined and treated as early as possible is one best way to avoid irreversible damages.
From late summer to autumn, the amount of hair loss is often the highest. Meanwhile, in winter and summer, the rate decreases significantly. This phenomenon has been examined in several studies, and the results suggested that it might be due to the reaction of the head insulation and the scalp against seasonal changes. The telogen phase extends to keep more hairs on your scalp during summer and winter. As a result, there is more hair shedding afterward.
It is beneficial to go beyond your usual routine and give extra care to your scalp to encourage new hair regrowth in replacement for the hair strands that fall. Besides shampoo and conditioner, using hair serum is a helpful way to nurture your scalp deeply.
Hsiang, E. Y., Semenov, Y. R., Aguh, C., & Kwatra, S. G. (n.d.). Seasonality of hair loss: A time series analysis of Google Trends data 2004 to 2016. 6.
Kunz, M., Seifert, B., & Trüeb, R. M. (n.d.). Seasonality of Hair Shedding in Healthy Women Complaining of Hair Loss. 6.Grover, C., & Khurana, A. (2013). Telogen effluvium. Indian Journal of Dermatology, Venereology, and Leprology, 79(5), 591.