How Scalp Hair Growth Cycle Works And Its Phases

How Scalp Hair Growth Cycle Works 

Hair Growth Cycle

A lot of peoples are suffering from Hair Fall and there are so many Hair fall causes behind it, which we have to understand. Hair regrowth and Hair fall is a complex subject than it looks on the surface. Before going deep into this topic, we need to understand the basic hair growth cycle so encountering these hairs fall causes & finding out solution will be much easier.

What is Hair Follicle?

It is the inner root of the scalp where the hair starts developing and into which sebaceous gland opens.

Each and every hair is having its own life cycle, it is the complete independent process i.e. from hair regrowth to hair fall.

So first of all, we will understand the basic Hair structure then we will go through their different phases.

Hair Structure consists of two parts

1. Hair Follicle

  • It is the base of the hair shaft which originates and resides into scalp skin i.e. which we also call as Hair Root.
  • The base of the follicle is papilla which contains tiny blood vessels that nourish the hair root cells for its growth.

2. Hair Shaft

  • The hair shaft is actually hair which is visible on the scalp.
  • Hair which we see is not a living structure and it is made from a protein called Keratin.
  • Hair shaft formed consist three layers
  1. The inner layer is called as Medulla and it can be only seen in think hair.
  2. The middle layer is Cortex which makes most of the hair shafts and provides a strength and texture to hair.
  3. The outer layer is Cuticle formed with a tight structure which is thin and colorless.
  • Our hair color which we see is just cortex and the medulla that holds the hair’s pigment.
  • Scalp skin having several functions according to its sheath layers.

Internal sheath

  • The internal sheath follows the hair shaft and ends below the opening of a sebaceous (oil) gland.

External sheath.

  • The external or outer sheath follows all the way up to the gland.
  • Erector pili muscle which attaches below the gland to a fibrous layer around the outer sheath.
  • When this muscle contracts, it causes the hair to stand up which also causes the sebaceous gland to secrete oil.

So now we will go thorough Hair growth cycle

Hair Growth Cycle & its phases

Hair Growth Cycle consists of 3 stages

  1. Anagen
  2. Catagen
  3. Telogen


  • It is growing and active period of a hair follicle.
  • The time span for this stage normally lasts about 3 to 5 years.
  • Sometimes hair Span length decided based on their genetics also.
  • In this stage in a month hair grows takes around half an inch.
  • And we can observe that most of the hair growth will occur in summer season than the winter.
  • So, at any given point of time 80 to 85% of hairs on any person’s head is in the anagen phase.


  • It is the transitional or intermediate period of hair growth.
  • Furthermore, in this phase the deeper portion of the follicle starts getting a shrink and finally detached from the base, which results in nurturing from blood supply will be stopped for those hairs.
  • So, because of this hair growth will not happen.
  • This phase normally remains almost for 7 to 15 days.
  • For any point of time 1 to 3% of hairs are coming at this stage


  • It is resting and shedding phase of the hair cycle.
  • In this stage, the hairs are released and fall out from your scalp.
  • And the same root will be inactive for 1 to 4 months and new hair regrowth will take place depending on the nutrient intake and supply it to the base root.
  • So, at any given point of time, 10-15% of the scalp hairs are into this stage.i.e. 25 to 100 hair falls in a day.


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