The Science Behind Hair Growth & Hair Loss

Hair Growth & Hair Loss

Hair Loss

Hair Beginnings 

Cycle of Hair Growth 

Take Away 

Hair is significantly more complicated than it appears at first glance. Almost all know that it not only affects men's and women's appearances, but it also aids in the transmission of sensory information and gender identity. 

Hair Beginnings 

A growing embryo has all of its hair follicles produced by week 22. There are around 5 million hair follicles on the body at this age. A total of one million follicles exist on the head, with one hundred thousand of them located on the scalp. Because we do not develop new hair follicles during our lives, this is the largest number of hair follicles a person will ever have. 

Most people will note that as they grow older, the density of their scalp hair decreases. The reason for this is because our scalps enlarge as we age. 

Follicles (hair follicles) 

The follicle, which is found in the skin, and the shaft, which is visible above the scalp, are the two separate structures of hair. 

The hair follicle is a tunnel-like epidermal segment that extends into the dermis. T The structure is made up of various levels, each of which serves a distinct purpose. Capillaries, or small blood veins, supply the cells of the papilla that are found at the root of the follicle. The bulb, which surrounds the papilla and is the living component of the hair, is the very lowest part of the hair. The bulb's cells divide every 23 to 72 hours, which is much quicker than every cell in the body. 

The follicle is surrounded by two sheaths: an inner and an outer sheath. The growing hair shaft is protected and formed by these structures. The hair shaft is followed by the inner sheath, which finishes below the orifice of a sebaceous (oil) gland and, in certain cases, an apocrine (scent) gland. All the upwards from to the gland, the outer sheath is still present. The arrector pili muscle joins to a fibrous layer around the outer sheath below the gland. When this muscle contracts, the hair stands up, causing the sebaceous gland to exude oil as well. 

The sebaceous gland is important because it generates sebum, which keeps hair and skin moisturised. During adolescence, our bodies produce more sebum, yet as we all get older, we generate less. Women produce much less oil than men as they mature. 

Shafts of Hair 

The hair shaft is composed of three layers of keratin, which is a rigid protein. Because this protein is no longer alive, the hair you perceive is not a living structure. The medulla is the innermost layer. The cortex is the second layer, and the cuticle is the outer layer. The majority of the hair shaft is made up of the cortex. The cuticle is a shingle-like structure made up of overlapping scales. The pigment that gives the hair its colour is held in both the cortex and the medulla. 

Cycle of Hair Growth 

Hair on the scalp grows at a rate of roughly.3 to.4 millimetres per day, or about 6 inches each year. Human hair growth and shedding, unlike that of other mammals, is unpredictable and not seasonal or cyclical. A pseudo-random of hairs will be in one of three stages of development and shedding at any one time: anagen, catagen, or telogen. 


The active form of hair is anagen. The cells in the hair's root are quickly dividing. A new hair grows in the follicle, pushing the club hair (a hair which has stopped developing or is no more in the anagen phase) up and out. 

Hair grows roughly 1 centimetre every 28 days during this phase. On the scalp, this active form of hair growth will last 2 to 6 years. 

Because they have a brief active period of growth, some people have difficulties developing their hair beyond just a specific length. People with exceptionally long hair, on the other hand, have a long active growth period. The active development phase of hair on the arms, thighs, lashes, and eyebrows is roughly 30 to 45 days, which explains why they are so considerably shorter than scalp hair. 


The catagen phase is a transitory stage in which around 3% of all hairs are at any given time. This phase typically lasts two to three weeks. The outer root sheath shrinks and adheres to the hair root, halting growth. The creation of a club hair can be seen here. 


Telogen is the dormant phase of hair growth, accounting for about 6% to 8% of any and all hairs. For hairs on the scalp, this phase lasts about 100 days, while it lasts longer for hairs on the eyebrow, eyelid, arm, and leg. The follicle is fully at rest during this phase, and the club hair is fully created. When you pull a hair out at this period, you'll find a firm, hard, dried, white substance at the root. About 25 to 100 telogen hair are lost each day.  

How to grow hair faster

Choosing the appropriate shampoo is the first step toward maintaining healthy hair. Look for products made specifically for your hair type, whether it's oily, dry, fine, colour-treated, or otherwise. 

Finding the appropriate conditioner also can create a change, although it may take some trial and error to locate the right products. Pay attention to how different shampoos and conditioners affect your hair. 

It's also crucial to treat your hair gently in order to promote healthy growth. When shampooing, avoid using excessively hot water and gently towel-dry your hair afterward. When hair is damp, it is more susceptible to damage. It's also possible that lowering the heat on your hair dryer will help. 

Take Away 

Anagen, catagen, telogen, and exogen are the four stages of hair development. Every phase lasts a set number of minutes. 

A stress-free lifestyle, a balanced diet, and careful hair care should all contribute to long-term hair development. 

Consult a doctor if you notice that you're shedding your hair at a quicker rate than usual. An underlying ailment that disrupts hair growth phases could be to blame, and addressing it quickly could help decrease hair loss and maintain the fine hair you still have. 

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