Understanding the Normal Hair Growth Cycle: A Biological Overview

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Written By harley haircentre
Diagram of the human hair growth cycle showing Anagen, Catagen, and Telogen phases.

Hair Growth Cycle

The average human head has around 90,000 –120,000 hair follicles, growing at an average of 0.5 to 1 centimetre per month. Each hair follicle follows a cycle of growth until it sheds at the end of the cycle. There are 3 main phases in the hair growth cycle:

1. ANAGEN (GROWING) PHASE

  • Growth phase of the hair follicle and new hair is formed.

  • Approximately 85-90% of the hair follicles spend 2 – 5 years in this phase.

  • This is the only phase where laser therapy is effective.

2. CATAGEN (TRANSITION) PHASE

  • Intermediate phase of hair growth.

  • Lasts for 1 – 2 weeks.

  • The dermal papillae - a group of cells that contain blood vessels and nutrients supplying the hair follicle, begins to separate from the hair follicle.

  • Hair follicles slowly transition into the resting phase.

3. TELOGEN (RESTING) PHASE

  • The dermal papilla is completely separated from the hair follicle.

  • Old hairs reach the end of their cycle and falls out.

  • Lasts for 3-4 months.

  • At the end of this phase, new hair growth is initiated.

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Understanding Male Hair Loss: The Role of Genetics and Hormones