During which phase does the hair follicle shrink and stop producing hair?

The hair follicle shrinks and stops producing hair during the catagen phase. This phase marks a transitional period in the hair growth cycle where the active growth phase ends, and the hair follicle begins to undergo a process of regression.

During catagen, which lasts a few weeks, the lower part of the hair follicle shrinks and detaches from the dermal papilla, the structure that supplies nutrients and signals for hair growth. This detachment results in the cessation of hair production. As the follicle shrinks, the hair strand can be pushed upwards and eventually comes to rest in the follicle, leading to its eventual shedding.

Understanding the hair growth cycle is essential for those in the barbering profession, especially in providing proper hair care and understanding hair loss patterns. The other phases—anagen, telogen, and exogen—represent different stages in the life of a hair strand, but it is during the catagen phase that the follicle significantly changes and halts hair production.