What is Hair and How Does it Grow? For Real


What is Hair and How Does it Grow? For Real

Let's set the record straight!

It can be pretty easy to gloss over the importance of the science behind something we feel we’ve spent our entire lives getting to know in our own way. But, if you can put up with some technical jargon for a whole post, we thought it would be helpful (and, maybe even a little fun) to go through the basic fundamentals of what our hair is, so you’re at least a little armed with the facts next time someone try’s to sell you about the latest "miracle" product.

What is hair?

It’s important to distinguish between the hair shaft that starts at the surface of the epidermis of the scalp and grows upwards vs. the dermal components of your hair, including the hair follicle/bulb, with its stem cells, blood supply, sebaceous (oil) glands and the inner and outer root sheath, as shown in the diagram above.

The hair shaft is made up of 3 layers- cuticle, cortex and medulla. The cuticle is the most outer layer of the shaft, hence the most susceptible to environmental and physical damage. It’s formed from dead cells composed of a protein called keratin. Yes, you read that right hair is DEAD. The cuticle protects the underlying cortex by providing a barrier to water and chemicals. Although the chemical composition of the cuticle is similar in all hair types there is decreasing thickness among cuticular layers depending on your ethnic background.

Majority of the mass and tensile strength of the hair shaft (what most of us can see everyday growing out of our scalps) can be attributed to the cortex. The cortex comprises keratin filament and melanin granules, which determine hair’s colour. While the medulla forms the porous, empty center of the hair fiber.

So, how does it grow?

Human hair follicle grows in a continuous cyclical pattern of 3 phases: anagen, catagen and telogen (bit of a mouthful).

  • The anagen phase, also known as the growth phase, is when blood from the blood vessels in your scalp feeds the hair bulb causing hair to be pushed out; this can last for 1-10 years.
  • Next is the catagen phase i.e. the transitory phase, lasting for usually 3 weeks, where the hair follicle detaches from nourishing blood supply.
  • And finally, the telogen phase lasts around 3 months. All growth stops, the bulb of the hair atrophies, the hair sheds and the growth cycle restarts.

At any given time, approximately 90% of the hairs on the scalp are in the anagen phase and 10-15% are in the telogen phase.

Why do things like growth oils not work?

Based on our explanation above, it’s clear hair growth is almost an entirely internal process. So, unless said ingredients are able to penetrate the epidermis, reduce the rate of follicle detachment or increase the blood circulation (e.g. like minoxidil) that product simply cannot impact your hair’s ability to grow.

Don’t be dissuaded by before and after photos because the truth is, most hair loss, especially in young people, is temporary. Unless there is a more serious underlying health condition and the hair follicle is not dead - the hair will likely grow back with healthy practices, troubleshooting the initial cause of  hair loss and patience. So just like we were taught in school - don’t confuse correlation with causation and save your coins!

Epidermis - outer layer of the skin