Hair Growth Cycle

What is a hair graft and follicle?

Hair is made up of 2 parts: the hair follicle and the hair shaft. The hair follicle anchors the hair into the scalp and is made up of the papilla and bulb, which are located beneath the scalp. The bulb can be found at the bottom of each strand containing the active cells which grow the hair around the papilla. The papilla provides the blood supply to the hair follicle to encourage healthy hair growth.

The hair shaft is the visible hair that grows out from the follicle which is made up of a hard protein called Keratin and a protective layer called the cuticle. There over 100,000 hair follicles on a full head of hair. Hair grows in cycles and it is common for people to lose up to dozens of hairs each day.

What is the hair growth cycle?

The hair growth cycle consists of four distinct stages: anagen, catagen, telogen and exogen

  • Anagen Phase: The period of hair growth. Hair grows around half an inch a month, and faster in the summer than in winter. The growth phase, lasts an average of 3-5 years. This phase is generally longer in Asian people and can last up to 7 years i.e. their hair can grow to 3 feet long!
  • Catagen Phase: Begins at the end of the anagen phase. Hair stops growing as much and this transitional phase lasts up to 10 days.
  • Telogen Phase: This is a resting period of around 3 months. Hair strands remain in their follicles but are not actively growing. 
  • Exogen Phase: the final stage where strands are released from their follicles and fall out. The growth cycle then begins again.

Hair loss, hair thinning and problems with hair growth may occur when the growth cycle is disrupted. This is usually caused by genetics, metabolic imbalances, illness or improper nutrition.