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Understanding the 4 Stages of Hair Growth

At any given moment, our hair is going through 1 of 4 stages of hair growth. In this article, we break down the science of hair growth.

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At any given moment, our hair is going through 1 of 4 stages of hair growth.

Each follicle goes through these phases independently. If all of our hair follicles went through the same growth stage at once, we’d all go through temporary periods of baldness!

Thankfully though, when some of our hair is in the growth period, other parts of the hair remain in a dormant state. To better understand hair loss and how to encourage hair growth, we first need to understand the natural cycles our hair goes through. In this article, we break down the science of hair growth.

Hair Structure

First up, let’s quickly pin down the overall structure of the hair. Our hair is primarily made up of two important parts: the hair follicle and the hair shaft.

More than 100,000 hair follicles anchor our hair deep into the scalp. The papilla, which lays beneath the hair follicle, offers blood supply to the hair follicle to encourage healthy hair growth. As the hair advances through the hair growth cycle, the star of the show is the hair follicle. This is where all the action happens!

The hair shaft is the visible part of the hair follicle. This is where you see the hair poking up from the scalp. This part of the scalp is mostly made up of a protein called Keratin and serves as a protective layer called a cuticle. The hair cuticle layer protects the hair shaft. (This layer, if it’s healthy, also offers a beautiful hair sheen!)

The 4 Stages of the Hair Growth Cycle

The average human head has about 100,000 hairs. At any given time, each one of these 100,000 hairs could be in 1 of 4 stages of hair growth.

Each hair operates independently and is on its own cycle trajectory. This is why it’s common to lose 100 to 150 hair strands a day, as a small percentage of hair is always going through the shedding (exogen) process. (Don’t worry though, a healthy regrowth cycle begins right after shedding!)Let’s break down the four hair growth phases

  • Anagen: growth
  • Catagen: transition
  • Telogen: resting
  • Exogen: shedding
stages of hair growth

#1 The Anagen Phase- Growth

Lasts 2 - 7 years

The first phase of hair growth begins with the anagen phase. During this phase, hair is in a state of continuous growth, for anywhere between 2 and 7 years. Interestingly, this phase determines the maximum length of your hair. If your hair only grows to a certain length, it might be due to a shorter anagen phase. During this phase, hair can grow between 18 to 30 inches in length. On average, hair grows about 1 cm every 28 days.

On average, 80-90% of your hair is actively growing in the anagen phase. However, many things can disrupt hair growth, resulting in a smaller percentage of hair sustaining the anagen growth phase.

#2 The Catagen Phase- Transition

Lasts around 10 days

During this short phase, the hair begins a transition from growth to dormancy. This phase is characterized by the hair follicle detaching itself from the blood supply.  While this may sound like the hair preparing to fall out, it’s not. In fact, the hair is simply preparing to stop any further growth. Even once the hair has detached from the blood supply, the hair follicle still holds it firmly in place during the resting phase that is to follow. At any given time, about 3% of all hairs are in this transitional phase.

#3 The Telogen Phase- Resting

Lasts around 3 months

After the hair follicle detaches from the blood supply and ceases its growth period, the hair goes into a state of resting; neither growing nor shedding. This period can last around 100 days.  As a result of detaching from the blood supply (the catagen phase), the hair that remains is what is known as “club hairs”. There is a “club-shaped knob” at the base of the hair which is what keeps the "club hairs" in place during the resting period. An average of 15% of the hairs on your head at any one time are club hairs.

#4 The Exogen Phase- Shedding

Technically a part of the telogen phase, the exogen phase is characterized by the shedding of resting “club hair”. While the shedding of hair might sound super scary, it’s actually a totally normal and healthy part of the hair growth cycle. During this phase, the “club hairs” are pushed out from the follicle as new anagen hair growth takes its place. Thus the cycle begins again. However, this shedding phase does not occur during every cycle, so club hairs might stick around for a longer period of time.  Because a small percentage of all hair is going through this exogen shedding process, it’s common to shed 100 to 150 strands of hair a day. Yet, there is a point where the rate of hair shedding is considered abnormal. There are health conditions that can disrupt the hair growth cycle and cause excessive hair shedding. Hair damage from chemical treatments and heat styling can also cause hair shedding.

Read related: How Many Hairs Do You Lose in a Day? Is Shedding Normal?

If your hair growth/shedding seems abnormal

If your hair shedding feels like it might be outside of the everyday shedding process, or you feel your hair is not growing at the rate it used to, you might be experiencing a form of excess hair shedding or hair loss. There are topical and medication treatment solutions.

For female hair loss

For male hair loss

Related: How to make your hair grow faster: 10 easy tips

Worried about hair loss? Strut Health can help

If you are dealing with hair loss or excessive hair shedding, there are treatments available to help aid the hair growth process. Our medical team is available for free 1:1 hair loss consultations. If our doctors find you are a good match for our prescription hair loss formulas, we can ship them directly to your door. Hair loss can be treatable, and Strut is here to help you get your locks back!

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