Human hair constantly undergoes a cycle of growth and rest. This sophisticated biological process ensures continuous renewal. Understanding this natural cycle helps demystify common observations, such as hair shedding.
The Hair Growth Cycle
Hair growth proceeds through a cyclical pattern involving several distinct phases. The first and longest phase is Anagen, the active growth stage, where hair follicles rapidly divide to produce new hair. Scalp hair typically remains in this phase for two to eight years, growing approximately 1 to 1.5 centimeters per month. About 85% to 90% of scalp hairs are in the Anagen phase at any given time.
Following the Anagen phase, hair enters the Catagen phase, a short transitional period. This stage lasts about two to three weeks, during which the hair follicle shrinks, and hair growth slows. The Catagen phase signals the end of active growth for an individual hair strand.
The third stage is the Telogen phase, which is a resting period for the hair follicle. During this time, the hair remains in the follicle but is not actively growing. The Telogen phase typically lasts around two to three months, and approximately 8% to 15% of scalp hairs are in this phase at any given moment. Finally, the Exogen phase is the active shedding of hair, where the old hair detaches to make way for new growth.
Identifying a Club Hair
A club hair is a normal hair strand that has reached the end of its growth cycle. It is named for the distinctive bulb-like structure at its root, which is light-colored or whitish. This bulb forms from keratin at the base of the hair shaft.
Club hairs begin to form during the Catagen phase as the hair follicle prepares for its resting state. The bulb anchors the hair until it is naturally shed. Their presence indicates the hair has completed its lifespan and is being replaced by new growth. When examining shed hairs, the presence of this small, rounded bulb at the root confirms it as a club hair.
Normal Shedding Versus Excessive Loss
Shedding club hairs is a natural and expected part of the hair renewal process. On average, individuals typically shed between 50 to 100 hairs per day. This amount is considered normal, and because the scalp contains around 100,000 hair follicles, this daily loss does not significantly affect overall hair density. The shedding often occurs during routine activities like washing, brushing, or styling hair.
However, a noticeable increase in shedding, where significantly more than 100 hairs are lost daily, may indicate a condition called telogen effluvium. This temporary form of hair loss occurs when a higher proportion of hairs prematurely enter the Telogen (resting) phase due to a systemic shock or stressor. Triggers can include significant stress, major illness, surgery, hormonal changes such as postpartum, or nutritional deficiencies.
Telogen effluvium results in excessive shedding of club hairs, often appearing two to four months after the triggering event. While the shedding can be alarming, it is typically a temporary condition where new hair continues to grow. If persistent, excessive shedding or noticeable thinning occurs, consulting a healthcare professional is advisable to determine the underlying cause and appropriate management.