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From Growth to Loss: The Stages of the Hair Follicle Explained

Hair Follicle Stages
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Written by Andrew Le, MD.
Medically reviewed by
Last updated May 10, 2024

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Ever wondered about the journey your hair takes from root to tip? This article will delve into the stages of the hair follicle to help you maintain healthy hair and even tackle hair loss issues.

Understanding the Hair Growth Cycle

Let's dive deeper into hair growth cycles and the role of the hair follicle in determining scalp health. Understanding how hair grows can help deal with issues such as thinning hair, hair loss, and more complex conditions like androgenetic alopecia.

What Is a Hair Follicle?

A hair follicle is not just a canal in your scalp where strands of hair sprout. Instead, it's a dynamic organ. An average human scalp possesses approximately 100,000 hair follicles, each independently going through its cycle of growth and rest.

Under normal circumstances, it's completely natural to shed 50-100 hair strands daily. This occurrence should not be misinterpreted as a sign of thinning hair or baldness. Frequent shedding is part of the hair follicle's cycle, contributing to your scalp’s overall health.

The Role of Hair Follicles in Scalp Health

The health of your hair depends on the health of your hair follicles. When follicles are functioning properly, they can keep up with the regular hair shedding and regrowth cycle. However, problems may arise when follicles become dormant or damaged.

For instance, certain forms of permanent hair loss, such as androgenetic alopecia, more commonly known as male or female pattern baldness, occur because hair follicles shrink over time. Similarly, cicatricial alopecia, also referred to as scarring alopecia, is a rare form of alopecia where inflammation damages and scars the hair follicle, leading to permanent hair loss.

Loss of hair could also occur due to medical treatments such as radiation therapy for cancer. The effects of therapy can cause temporary to permanent hair loss, depending on the treatment's intensity.

The Anagen Phase: Active Hair Growth

One of the stages of hair growth is called the anagen phase, or the active growth phase.

Duration and Characteristics of the Anagen Phase

The anagen phase is the period where our hair follicles are busy at work. They're actively producing new cells that push up the older, dead cells through the scalp, leading to the growth of hair. Primarily, the hair you see is a string of dead keratin cells.

The length of this phase is genetic and typically ranges from two to seven years. The longer the anagen phase, the longer your hair grows. At any given time, about 90% of the hair on a healthy scalp is in the anagen phase.

Conditions such as androgenetic alopecia or male pattern baldness can affect this phase. They lead to hair follicle shrinking, which results in shorter and thinner hair strands.

How to Support Hair During the Anagen Phase

Hair during the anagen phase loves nourishment! Feeding your hair follicles with vitamins, especially vitamin A may help hair health. Vitamin A aids in the production of sebum (oil), keeping the scalp moisturized.

Eat a balanced diet, and avoid any unnecessary stress on the hair from aggressive styling or high-heat tools.

Whether you're dealing with hair thinning, excessive hair loss or even bald spots, identifying and supporting your hair during its active growth phase can be a game changer.

The Catagen Phase: Transition and Regression

After the anagen phase, the hair follicle enters the short-lived catagen phase. This stage, sandwiched between the active growth phase and the resting one, is the period of transition and regression. Understanding this phase can shed light on conditions like thinning hair.

Understanding the Short-Lived Catagen Phase

This phase typically lasts for about 2-3 weeks and is the briefest stage. Despite its short duration, this phase plays a critical role in preparing the hair for its next growth cycle.

This transitional phase signals the end of active hair growth from the anagen phase. It's in this phase where hair follicles start to shrink, and hair strands effectively disconnect from the blood supply. The catagen phase contributes to hair thinning or alopecia, as it's the phase that regulates how often and when your hair follicles should replenish your strands.

The Biological Processes of Hair Transition

During the catagen phase, the lower two-thirds of the hair follicle starts to disintegrate, triggered by internal signals within the body. This process causes a gradual shrinkage known as follicle miniaturization. The level of follicle miniaturization can vary from one person to another, and excessive shrinkage can potentially lead to male or female pattern baldness.

However, at the same time, a protective layer known as the dermal sheath starts to form around the part of the hair follicle that remains intact. This sheath sets the stage for the telogen phase.

The Telogen Phase: Rest and Renewal

After the transitional catagen phase, hair follicles enter the telogen, or resting, phase. This phase typically lasts between three and four months. During telogen, the follicle is in a state of rest and no active hair growth occurs. The telogen phase might be a resting period, but it's far from being a dormant phase. It acts as a reset for your hair follicles.

Identifying Signs of the Telogen Phase

This is the stage that affects hair thinning or hair loss. Experiencing thinning hair or hair loss in this phase is typically a sign of telogen effluvium, a condition often triggered by severe stress, malnutrition, or a major life event, like childbirth. Isolated bald spots or patchy hair loss might indicate conditions such as cicatricial alopecia or traction alopecia.

The Importance of the Telogen Phase in Hair Renewal

Many factors such as age, genetic predispositions like androgenetic alopecia (male or female pattern baldness), scalp health, and even lifestyle choices can all impact the duration and effects of the telogen phase.

Management and treatment for hair thinning and loss associated with the telogen phase typically target the underlying issues. Options range from hair replacement, and hair transplantation to medications.

Factors Influencing Hair Growth and Loss

There are numerous factors that can affect the health of your hair, potentially leading to conditions like hair thinning, alopecia, and even baldness in both males and females.

Genetic Factors vs. Environmental Factors

Conditions like androgenetic alopecia, also known as male pattern baldness and female pattern baldness, are predominantly driven by your genes. If you've relatives who've experienced hair loss, you're more likely to experience it too.

In some cases hair loss can be triggered by illness or treatments. Take for instance cancer treatments. Both chemotherapy and radiation therapy can lead to temporary or even permanent hair loss. Likewise, excessive hair loss can be a side effect of some medications.

Stress can also cause hair loss, such as with telogen effluvium, where more hair follicles enter the telogen phase, leading to thinning hair or excessive hair loss.

The Impact of Diet and Nutrition on Hair Health

Your diet and nutrition can affect hair health.

Deficiencies in certain nutrients, specifically vitamin A, can push more follicles into the telogen phase. This causes thinning hair or even excessive loss.

Studies have shown that diets rich in iron, protein, and omega-3 fatty acids can encourage hair regrowth. Supplements, such as biotin, are also commonly suggested for hair health, especially for those with bald spots or pattern baldness.

Common Misconceptions About Hair Growth and Loss

There's a lot of misinformation about hair growth and loss, some of it perpetuated by old wives' tales, some by misleading marketing.

Debunking Hair Growth Myths

  1. Myth: Cutting hair makes it grow faster. Not true. Your hair's growth rate is determined by the hair follicle and trimming your hair doesn't affect the follicle. This belief may stem from the fact that trimming can eliminate split ends and reduce breakage, giving the impression of thicker, healthier hair.
  2. Myth: Male and female pattern baldness comes from the maternal side of the family. In reality, genetics from both parents play a role in the likelihood of developing this type of baldness.

Realities of Hair Loss and Regrowth

One misconception is that stress can lead to permanent hair loss. While stress can push more hair follicles into the telogen phase (known as telogen effluvium) causing temporary hair thinning, it's rare that this would lead to permanent damage. Generally, hair starts to regrow once the stressful event or period has passed.

One common belief that is true is that tightly pulled hairstyles damage hair follicles and can lead to permanent hair loss. That’s called traction alopecia. However, it's often misconstrued that any tension on the scalp will cause hair loss. In fact, it takes a persistent pulling force to cause traction alopecia, so your regular ponytail or bun is unlikely to do harm unless it's causing discomfort.

Frequently Asked Questions

Does cutting hair make it grow faster?

No, this is a common myth. Hair growth is determined at the root, not by how often the ends are trimmed.

Is pattern baldness only inherited from the maternal side?

That's a misconception. While genes from the maternal side can influence this, baldness is actually a trait that can be inherited from both parents.

Can stress cause hair thinning?

Yes, temporary hair thinning may occur from high stress. Stress can shock the hair cycle, prompting more hair to shift into the shedding phase. This condition, though, is often reversible.

Do tightly pulled hairstyles cause hair loss?

Yes, traction alopecia is hair loss caused due to tension on the hair from tightly pulled hairstyles. It can be prevented by avoiding hairstyles that pull tightly on the hair.

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Jeff brings to Buoy over 20 years of clinical experience as a physician assistant in urgent care and internal medicine. He also has extensive experience in healthcare administration, most recently as developer and director of an urgent care center. While completing his doctorate in Health Sciences at A.T. Still University, Jeff studied population health, healthcare systems, and evidence-based medi...
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