Hair Growth Cycle: Structure of Hair & 3 Stages Explained

Do you feel alarmed every time you notice hair fall? Are you aware that hair shedding is a regular part of the hair growth cycle? Well, losing 50-100 strands a day is normal, and you need not panic. Keep reading to know all about the hair growth cycle and get answers to all your queries related to hair fall and renewal.

What Is The Structure Of The Human Hair?

Hair consists of two major parts – hair follicle and hair shaft. The hair follicle is responsible for anchoring the hair into the scalp. Each hair follicle has a hair bulb located at the base that contains actively growing hair cells. The blood vessels in the hair bulb supply hormones that affect the growth and structure of hair throughout life. The melanocytes present in the hair bulb produce melanin that makes the hair black.

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The hair shaft is the visible part of the hair that grows out of the hair follicle. It comprises of a hard protein called keratin and a protective layer known as the cuticle. The cuticle consists of overlapping cells that are responsible for the strength, flexibility and shine of the hair. Cortex is the most important layer of the hair shaft as it forms 75 to 90% of its volume and is responsible for its elasticity and colour. The spongy core of the hair shaft or medulla is responsible for supplying it with nutrients and removing the waste.

What Is The Hair Growth Cycle?

Hair growth is cyclical in nature and consists of three distinct stages.  Each of them is responsible for a change in the texture and appearance of hair. Check out the video below to gain insight into  the hair growth cycle:

What Are The Three Stages Of Hair Growth Cycle?

Hair growth cycle consists of the following stages:

• The Anagen or Growth Stage: The hair grows and thickens in the anagen stage as the cells in the hair bulb proliferate rapidly. It lasts for about three to five years before hair follicles become dormant.
• The Catagen or Intermediate Stage: It is the transition phase when the hair follicles prepare themselves after active growth for the resting stage, and it lasts around one to three weeks. The appearance of club hair characterises this intermediate phase when the hair shaft separates from its roots. The hair follicles shrink and lose about 15% of its diameter as their deeper portions collapse.
• The Telogen or Shedding Stage: It is the final stage of the hair growth cycle that starts with resting and then shedding of hair. The hair follicle remains dormant, and the hair shaft stops growing. Up to 15% of our body hair is in this stage at any point in time. It usually lasts for about three to four months during which the resting club hairs fall out and allow new hair growth to occur. Around 75-100 hairs are shed each day during the telogen phase.

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For optimum and healthy hair growth, hair needs to stay as long as possible in the anagen stage. Around 85% of hair follicles remain in the anagen stage in a healthy adult. Typically, there are over 1,00,000 hair follicles on the scalp, which is why it is normal to lose over 100 hairs in a day.

Why Does Hair Fall?

Now you know that hair shedding is a normal part of the hair growth cycle, and it paves the way for new hair growth. However, any disruption of the hair growth cycle may result in acute hair fall and hair thinning. Some of the significant factors that trigger hair loss and lead to excessive hair shedding include genetic predisposition, hormonal fluctuations, high-stress levels, poor lifestyle habits, nutritional deficiency and side-effects of certain medications like chemotherapy. Excessive heat styling and chemical treatment, auto-immune disorders, allergic reactions to hair-care products and scalp conditions like Seborrheic dermatitis or Psoriasis too may result in increased hair fall.

What Can You Do To Maintain Healthy Hair Growth?

Here are a few simple tips for maintaining healthy hair growth:

• Follow A Regular Hair-care Routine: Maintain hair hygiene by using a mild shampoo and conditioner suitable for your hair type. Ask your dermatologist to recommend the right hair-care products for you to keep your hair healthy and scalp clean.
• Consume A Healthy Diet: Opt for a balanced diet comprising of the right amount of proteins, carbohydrates and fats, along with essential vitamins and minerals such as biotin, Vitamin B12 and B6, iron and zinc.
• Opt For Safe Hair Regrowth Treatments: Go for platelet-rich plasma therapy or PRP. It is an effective non-surgical treatment for reversing hair thinning, restoring hairline and promoting hair regrowth naturally.

A word of advice, consult an experienced dermato-trichologist immediately if you notice excessive hair shedding for accurate diagnosis of the underlying cause and suitable treatment. Timely action can help you restore healthy hair growth and prevent irreversible hair loss.