Your hair may be made of a lot of dead cells – but it’s more alive than you think. Like the other parts of your body, it undergoes several growth cycles. Because of these, your strands grow as much as 0.3 to 0.4 millimeters a day – which corresponds to about 6 inches a year.
The Hair Follicle
Hair is indeed more than skin deep, as it originates from the follicle. Also known as the hair root, its shape determines the pattern of your hair. If you have straight hair, then you have a cylindrical-shaped follicle. If you have curly hair, then your follicle bears a twisty shape.
Apart from shaping your hair literally, the hair follicle also undergoes cycles of regeneration. As such, this mini-organ is actually responsible for the hair growth cycle, which is comprised of the following:
Otherwise known as the hair growth phase, the anagen cycle is the time when cells divide rapidly – resulting in more new hair cells. In fact, most of your hairs – 80% of them – are undergoing anagen right now.
What you see on your head (and other parts) of your body are older cells that are pushed upward by the new cells developing near the root.
A third of each hair strand is made up of dead cells. These are keratinized, meaning they are filled with protein filaments. The same thing occurs with your nails. Thanks to this process, hair (and nails too) become tough and resistant.
As the hair cells emerge out of the follicle, these change in shape – giving rise to the hair strands that you see.
The growth phase lasts anywhere from 2 to 8 years. During this cycle, you grow as much as 1 centimeter of head hair every 28 days.
The phase is slower for your eyebrows, eyelashes, arm hair, and leg hair, which would explain their small sizes. In these hairs, the anagen phase only lasts for 30 to 45 days.
Also known as involution or transition, catagen signifies the end of the growth phase. This stage lasts anywhere from 10 to 14 days. It affects 3% of all of your hair at any given time.
When the hair enters the transition stage, the strands detach from the hair follicles – resulting in a structure known as a club hair. The bulb begins to break down, while the hair follicles gradually become shorter.
The telogen cycle, also known as the resting phase, lasts from 90 to 100 days for head hair. It’s even much longer for the eyebrows, eyelashes, arm, and leg hair.
On average, 14% of all of your hairs are undergoing the telogen phase.
If you pull out a strand and see a hard, dry white material on the root part, it means that this hair is currently ‘resting’.
After the telogen phase, the secondary or root germ, which is the remaining root sheath, begins to form hair anew. The anagen or growth phase begins again.
What Disrupts the Hair Growth Cycle?
On any given day, you can shed about 50 to 100 hair strands a day. Should there be more, it might mean that you are suffering from alopecia or hair loss.
While hair growth is a synchronized and timely process in the body, some factors may disrupt it. As a result, your hair may shed faster than usual. It may also become thinner and more brittle.
Here are the factors that may lead to such hair problems:
With aging comes hair loss. Not only is hair growth slowed, but the strands become smaller and less pigmented as well.
In men, typically hair loss starts at age 30, with some getting completely bald by age 60.
The baldness gene is found in the X chromosome, which men get from their mothers. While baldness among maternal relatives play a bigger role, having a balding father puts you at risk of hair loss as well.
Lack of certain nutrients, including Vitamin B6, B12, folic acid, protein, iron, zinc, magnesium, and essential fatty acids may affect the normal hair growth process.
Thyroid and autoimmune diseases are some conditions that may bring about hair loss.
Dihydrotestosterone, also known as DHT, is a derivative of the male hormone testosterone. It works by binding to your hair follicles, shrinking them in the process. As a result, healthy hair is no longer able to grow from these roots.
DHT is responsible for androgenetic alopecia, also known as male or female-pattern baldness.
Men with this condition usually develop M-shaped baldness. As for females, DHT can lead to less dense hair and a more visible scalp.
Stress is related to a variety of hair loss conditions, the most notable of which is telogen effluvium. Stress can prod the hairs on your body to enter the resting phase, which could last for 100 days. Profound hair loss, which materializes after combing or washing your hair, can occur in a few months.
Anti-cancer drugs are good examples of medications that affect hair growth. These drugs cannot differentiate healthy, rapidly growing cells (hair) from the harmful ones (cancer cells). They end up disrupting the oxygen supply of these cells – forcing the hair to enter the transitional phase.
More Hair Growth FAQs
A person who manages to grow long locks owes it to his/her longer active phase of growth. Asians are said to have a longer anagen phase, and as such can grow hair for as long as 0.5 meters.
Some people, unfortunately, may have a shorter active phase of growth. This would lead to strands not growing beyond a certain length.
Yes. The transitional and resting phase last for 3 to 4 months, which would explain why you don’t see the effects right away. As such, you could only see the results when the hair begins to enter the growth phase – which occurs several months after.
Hair growth is composed of three phases: anagen, catagen, and telogen. While these occur routinely, several factors may disrupt the process. With that being said, you need to avoid such stressors if you want to keep your hair long, strong, and healthy.