What is the Origin of Hair Cycling?

The term combines "hair," derived from the Old English hær, with "cycling," from the Greek kyklos (circle), signifying a recurring series of events. This nomenclature reflects the observation that hair follicles do not grow continuously but rather follow a predetermined, rhythmic pattern of activity and dormancy. The concept is central to the field of trichology and dermatology.

What is the Mechanism of Hair Cycling?

The initiation of the anagen phase is governed by growth factors that stimulate the dermal papilla cells to proliferate and form a new hair shaft. The catagen phase is a transitional period marked by programmed cell death (apoptosis) in the lower part of the follicle, leading to its shrinkage. Finally, the telogen phase is a quiescent period where the club hair is retained until the follicle re-enters anagen, pushing the old hair out. Hormones, particularly androgens, can shorten the anagen phase in genetically susceptible follicles, leading to miniaturization.

Hair Cycling ∞ Area

Hair Cycling

Meaning

Hair cycling refers to the continuous, repetitive process of growth, regression, and rest that every hair follicle on the body undergoes throughout its lifespan. This cyclical activity is tightly regulated by complex interactions between various growth factors, cytokines, and hormones, ensuring a continuous renewal of the hair shaft. Understanding the phases of hair cycling—anagen (growth), catagen (regression), and telogen (rest)—is essential for diagnosing and treating common hair loss conditions. The duration of the anagen phase dictates the maximum length a hair can achieve.