4 Most important things to know about hair growth

Being able to grow hair long and healthy from our scalp is something a lot of us strive for and over the years, People have always been gullible to anything concerning hair or hair growth (me especially). From black women being told to use relaxers to make their hair look more beautiful, products promising expeditious hair growth results in a very little amount of time or people taking up “uncertain hair practices” to solve the issue of hair loss. Nowadays, both men and women are willing to pay any amount of money to find out the secret behind healthy hair.

This is my first blog post and today’s topic might not necessarily be the most interesting topic but it’s definitely the most important one for a powerful foundation as you commence your hair journey. It’s a summary 4 things concerning the basics of hair growth that will help us all make more informed choices for our hair such that when we see products promising hair growth we know what it’s all about and not some kind of miracle as I hitherto imagined.

1. Hair grows in phases

Explaining the hair growth cycle in the simplest way possible, hair on our head grows from a root found at the bottom of a follicle beneath our scalp. The follicle serves as an anchor, holding the hair deep into our skin. This root, also known as hair bulb is made up of cells of protein that divide and grow to form our hair shaft. Blood from the blood vessels in our scalp feeds the root and the hair gets pushed up through the skin as the cells grow, passing an oil gland along the way. The oil gland adds oil known as sebum to the hair which keeps it shiny, soft and a little greasy. Hence hair is a non-living structure made up of dead cells of protein called keratin. Hair grows because matrix cells shed as they reach the upper follicle and the shed structure combines with keratins to form hair strands that exit our skin’s surface.

Our hair growth cycle consists of 4 stages namely: anagen, catagen, telogen, and exogen.

i. Anagen:

Also known as the growth phase. It is the phase where the hair bulb still receives nutrient from the blood vessels. This is the phase where our hair physically grows approximately 1 cm per month and It begins in the papilla. The papilla is a connective tissue that connects to the blood and supplies nutrients to growing hair. When one of our hair is in the anagen phase, the cells in the papilla are dividing to produce new hair fibers, and the follicle buries itself deep in the dermal layer of the skin into the blood supply to nourish the hair strand. The time period at which our hair remains in this stage of growth is determined by genetics and the longer our hair stays in this phase, the longer it will grow. About 85% – 90% of the hair on one’s head is in the anagen phase at any given time.

ii. Catagen:

Also known as the transitional phase. At this phase, the hair bulb slowly pulls away from the blood supply. During this time, our hair follicle shrinks due to disintegration causing the papilla to detach from the follicle’s base, thereby cutting the hair strand off from its nourishing blood supply. Signals sent out by the body determine when our hair’s anagen phase ends and when the catagen phase begins for a hair strand at any given time. After our body signals to our hair follicle that the strand it is working on has reached maximum growth, the follicle slowly dries up and stops feeding the hair shaft with new cells. In the catagen phase, the hair still gets pushed further up the shaft for a while, so it appears to get a little longer, but it’s not actually growing.

iii. Telogen:

Also known as the resting phase. At this point, our hair strand receives no nourishment from the blood vessels. During the telogen or resting phase, the follicle remains dormant for a while. The epidermal cells lining the follicle channel continue to grow as normal and may accumulate around the base of the hair, temporarily anchoring the hair shaft in place and preserving it for its future shedding. At some point, the follicle begins to grow again, thereby softening the anchor point of the shaft. The hair shaft later eventually breaks free from the root and the hair is ready to be shed naturally. Within a few weeks, a new hair shaft begins to emerge marking the end of the telogen phase. 10% to 15% percent of the hair on our head is in this phase of growth at any given time.

iv. Exogen:

also as early anagen or shedding phase. Many write-ups do not include it but Exogen is an active, separately controlled phase of the hair growth cycle. This phase consists of the resting hair reaching its terminal position in the follicle, new hair pushes the hair that has stopped growing, up the follicle and the old hair exits the scalp. This hair detaches/sheds allowing for new growth to come through. Every human being sheds about 50 to 150 hair strands per day due to the exogen phase. Roughly 1 % of hair in telogen phase sheds every day and the casual levels of exogen hair is < 7/cm2.

2. Each phase of the hair growth cycle has a given duration

It’s important to know how long each phase lasts on the hair growth cycle 80%of our hair is in its anagen phase. It is the longest phase of hair growth usually lasting several years and how long it lasts varies per individual. Depending on your hair strand and your genes, the anagen phase can last between 2 to 6 yrs.

Why your hair seems to stop growing

The amount of time that the hair spends in this phase is primarily determined by genetics and the longer the hair stays in the anagen phase, the faster and longer it will grow. Some people having difficulty growing their hair beyond a certain length could be because they have a short phase of growth (anagen phase). On the other hand, people with very long hair have a long anagen phase. How long the anagen phase lasts depends on if the cells in your follicle base are continuing to multiply and become hair cells. The hair on the arms, legs, eyelashes, and eyebrows have a very short anagen phase of about 30 to 45 days, reasons why they are so much shorter than scalp hair.

Our scalp hair grows about 0.3 to 0.4 mm/day which sums up to a rate of approximately 0.5 inches (1.25cm) per month or about 6 inches (15cm) per year. Researchers are still looking into what triggers our bodies to “turn on”the anagen phases. But there are steps you can take to promote healthy hair during the anagen phase for maximum hair growth.

How long each phase lasts

As long as the anagen phase lasts, your hair will keep growing longer, unless you trim or break it. On the other hand about 3% of our hair is in the catagen phase at any given time. This phase lasts approximately 10 to 20 days, which is about two to three weeks. Growth stops, the outer root sheath begins to shrink and attach to the root of the hair leading to the formation of what is commonly known as a club hair. Telogen is the resting phase and usually accounts for 6% to 8% of all hairs. This phase lasts for about 100 days for hairs on the scalp which is approximately 3 months. This phase lasts longer for hair on the eyebrow, eyelash, arm, and leg. During this phase, the hair follicle is completely at rest and club hair is completely formed. Pulling out a hair in this phase will reveal a solid, hard, dry, white material at the root of the strand. About 50 to 150 telogen hairs shed normally each day  

3. Each hair strand grows how it chooses irrespective of neighboring strands.

Each hair follicle is independent of the others and undergoes its own hair growth cycle at different times from each other. This is what prevents our hair from falling out all at once. Unlike in animals, our hair growth and shedding is random and not seasonal or cyclical. At any given time, a random number of hair will be in one of four stages of growth and shedding: anagen, catagen, telogen and exogen.

Each hair follicle goes through its own phase at its own pace regardless of the hair around it and follows its own growth cycle independent of the hair that surrounds it. Each strand of hair on the human body is at its own stage of development. Reasons why for some of us, hair on our edges seem to grow at a slower pace than hair on the rest of our head. Hairs on the perimeter of our head tend to have shorter anagen phases but the same strand of hair can change it’s growth rate through out it’s life time. So do not be scared if all your hair doesn’t reach a given length at the same time even when you do all the right things, it’s just because each hair strand does it’s own thing, you can’t be in control of everything so relax.

4. How Genes and Hormones affect Hair growth

Like the rest of our body tissues, the state of our hair is related to our overall health as well as our individual physical characteristics. The rate at which our hair grows can be affected by our genes and hormones. From the book Science of Black Hair, the author refers to genes as the climate and our hormones are the weather. The climate sets the pace of what type of weather is possible, in other words, our genes set the pace of what type of hair growth is possible. Our genes determine how long we can spend in each phase, setting the limits and the baselines of what growth we can achieve. Meanwhile, our hormones vary based on the genetic limits and are affected by the environment around us. Our diet, age, health and even the products we use can affect our hormones.

The role hormones play

A typical depiction of the role hormones play can be seen in the case of pregnancy. During pregnancy, antenatal hormones set the body into growing phase causing most hair strands to kick-start the anagen phase and after pregnancy they quickly usher you into resting phases causing postpartum shedding. Most of the hair goes into telophase reasons why women shed a lot of hair after pregnancy. Hormones also trigger rapid hair growth during puberty and hair loss or thinning as we age. Hair strands begin to change during puberty when large amounts of male and female hormones arrive in the blood.

The hair growth cycle is determined by the influence of these hormones produced by the endocrine gland and transported in the blood. These hormones then bond to target cells, which in this case is the roots of the hair. The roots of the hair capture the hormone’s signal from the blood and reacts as a result of the blood’s constitution. As we might have already guessed, hormones not only stimulate hair growth but also hair loss. Hence, understanding the interplay between our hormonal balance and diet can help speed up hair growth and prevent the most distressing aspects of hair loss.

How male and female hormones influence hair growth

There are 2 types of hormones: male or androgenic hormones, such as testosterone, and female or estrogen hormones such as progesterone. These hormones play a role in the body and particularly in the hair cycle. Female or estrogen hormones participate in hair growth by slowing down growth and prolonging the anagen phase. Inversely, male or androgenic hormones accelerate the hair cycle. Strictly speaking, androgens alone do not trigger hair loss. This is, in fact, the result of a chemical reaction, DHT, which is triggered by the combination of androgens and alpha reductase, an enzyme found in the scalp. DHT accelerates the hair growth cycle to such an extent that the hair follicles become saturated and begin producing shorter and shorter hairs until they are worn out. They are then able to produce only a fine layer of “fuzz”, and then nothing at all. These inactive follicles retract into the dermis and the skin becomes smoother (a typical balding process).

Men and women secrete male and female hormones but in different quantities. Women also produce androgens but in quantities 20 times less than men. This is why women never go bald, except in cases of disease or particular hormone disorders. However, they can experience increased hair loss or a modification in hair texture caused by a drop in female hormone production during menopause.

In conclusion

I can’t stress enough how important it is to know these details as a foundation for a better hair journey experience. Hair care can be challenging whether you have relaxed, texlaxed or natural hair, the curlier the harder. Sometimes I get frustrated wondering why my hair seemingly does not grow or doesn’t react well to hair treatments. It’s like no matter what I do, I still keep losing hair, my edges keep falling out, my hair won’t grow past my shoulders, how do I achieve volume. Ofcourse this is not an exhaustive list of everything you must know but it’s definitely a good basic to start from for better understanding of hair health and the mechanisms at the back of it.

Over the years, I’ve learned that there are several factors that influence our hair growth rate like age, diet, exercise, illness, stress etc. But most times, it all narrows down to our genes and hormones. Since we have no control over what genes we get and we have very limited control over our hormones, or hair growth phases, our primary aim should be giving our 100% best at what we can control which is keeping our hair healthy and length retention.

To help your hair attain its full-length potential, check out my next post on length retention.