Understanding the Hair Growth Cycle

Your hair is more than just a feature that contributes to your overall look—it's a dynamic part of your body that goes through a complex cycle of growth and rest. Understanding the hair growth cycle can give you insights into the nature of hair health and loss.

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The Four Stages of Hair Growth

The hair growth cycle is divided into four distinct stages: Anagen, Catagen, Telogen, and Exogen.

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Anagen (Growth Phase)

During this phase, your hair follicles are actively producing new cells that make up the hair shaft. This phase lasts on average 2-6 years, during which your hair can grow up to half an inch per month. The length of this phase determines the maximum length of your hair.

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Catagen (Transitional Phase)

This short phase, lasting around two weeks, signals the end of the active growth stage. During catagen, the hair follicle shrinks and detaches from the dermal papilla, which supplies nutrients to the hair.

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Telogen (Resting Phase)

During the telogen phase, which lasts about 1-4 months, the hair follicle is inactive and the hair, now termed a 'club hair,' is no longer growing. Around 10-15% of all hairs on your scalp are in this phase at any given time.

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Exogen (Shedding Phase)

This is the phase during which hairs are released and fall out, and new hairs begin to form. It's normal to shed 50-100 hairs per day in this phase.

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The Hair Growth Cycle and Hair Loss

Hair loss can occur when the growth cycle is disrupted. Factors such as stress, hormonal changes, illness, or certain medications can shorten the anagen phase and push more hairs into the telogen phase. The result is a condition known as telogen effluvium, which causes temporary hair shedding.

In contrast, in androgenetic alopecia (commonly known as male or female pattern baldness), the hair follicle's sensitivity to hormones like DHT can cause the anagen phase to shorten over time. This leads to progressively shorter and thinner hairs, and eventually, the follicle may stop producing new hairs altogether.

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Maintaining Healthy Hair Growth

Maintaining a balanced diet rich in proteins, vitamins, and minerals can support healthy hair growth. Key nutrients include iron, vitamin D, biotin, and zinc. Avoiding harsh hair care products and high-stress levels can also help keep your hair growth cycle in balance.

Understanding the hair growth cycle offers a foundation for better hair care and can provide insights into the causes and potential treatments for hair loss. Remember, using tools like the Hairly app can help monitor your hair's progress and health over time.