“What Are the Key Phases of the Hair Growth Cycle?”

Understanding the hair growth cycle can make a significant difference in maintaining healthy hair. The process involves four distinct phases: anagen, catagen, telogen, and exogen. Each stage plays a crucial role in how hair grows and sheds.

Nutrition and overall health significantly impact growth phases. By ensuring proper nutrition and taking steps to maintain health, one can support a healthy hair growth cycle. Age and lifestyle choices can also affect this timeline, making it essential to understand how to prevent and treat potential premature hair loss.

Regularly reading about hair care can help you learn more about effective ways to support your twisty treasure growth and activity.

What Are the Stages of Hair Growth?

The Growing Phase: Anagen

The anagen phase is the longest stage in the hair growth cycle, often lasting several years. During this time, hairs on your head can continue growing for up to seven years. This phase varies by types of hair, with eyebrow and pubic hairs having a much shorter anagen phase compared to scalp hairs.

In the anagen phase, follicles are pushing out new hairs, which will grow until they are cut or reach the end of their lifespan and fall out. Around 90 percent of your hairs are in this active phase. The hair follicle takes on an onion-like shape and works to produce the hair fiber. 

The anagen phase is broken down into Proanagen and Metanagen phases, 

• In Proanagen phase, the follicle proliferates progenitor cells and begins the differentiation process. 
• The new hair shaft appears on the skin’s surface during the Metanagen phase.

How Much Does Your Hair Grow?

During the anagen phase, your hair grows about half an inch a month, or roughly 6 inches a year. Interestingly, hair tends to grow faster in the summer than in the winter. This variation can be due to several factors, including increased blood circulation to the scalp during warmer months.

The Transition Phase: Catagen

The catagen phase starts when the anagen phase ends and lasts about 10 days. During this time, hair follicles shrink, and growth slows. Hair separates from the bottom of the follicle but stays in place during its final days of growing. Only about 5 percent of hairs on your head are in this phase at any given time.

The catagen phase is characterized by a transition into quiescence and can last a few weeks. The follicle undergoes apoptosis-driven regression, reducing its diameter. During this phase, a club hair forms, which is a key prognostic indicator for assessing hair pathology. If many hairs form club hair and shed simultaneously, it can cause thinning.

This can occur due to conditions like hypothyroidism, hyperthyroidism, stress, vitamin deficiencies, and post-childbirth. The hair cycle enters this short transitional phase, which signals the end of active growth and cuts the hair off from the blood supply and the cells that produce new hair.

How long does the Catagen Stage last?

At about 10 days.

The Resting Phase: Telogen

The telogen phase is the resting phase in the hair growth cycle and typically lasts around 3 months. During this time, an estimated 10 to 15 percent of your scalp hairs are in this phase. Hairs don’t grow during telogen, but they usually don’t fall out either. New hairs start to form in the follicles that have just released hairs during the catagen phase.

Some health experts consider the telogen phase as part of the shedding phase, while scientists have divided it into two stages: telogen and exogen. In the telogen phase, the hair follicle is dormant, and growth of the hair shaft does not occur. About 10 to 15% of all hairs on the body are in this state at any given time.

This phase can vary depending on the location of the hair, lasting a few weeks for eyelashes to nearly one year for scalp hair. The exact mechanism that controls the passage from one phase to the next is not fully known.

How long does the Telogen Stage last?

It usually lasts about 3 months or 100 days.

The Shedding Phase: Exogen

The exogen phase is an extension of the telogen stage in the hair growth cycle. During this phase, hair is shed from the scalp, often helped by washing and brushing. It’s normal to lose 50 to 100 hairs per day during this time. As old hairs fall away, new hairs are growing in the follicles.

In this phase, individual hair strands are released from their follicles and fall out. This shedding is part of the natural cycle, allowing the whole process to begin again.

How long does the Exogen Stage last?

It usually lasts for 2 to 5 months.

What Happens When the Hair Growth Cycle is Disrupted?

Each hair follicle is independent and goes through the growth cycle at different times. Otherwise, all your hair would fall out at once! Typically, you shed a certain number of hairs each day — about 80 to 100 hairs on a healthy head of hair. However, hair loss, thinning, and other problems can occur when this cycle is disrupted.

This disruption can be triggered by conditions like metabolic imbalances, illness, or improper nutrition. For instance, about 12 weeks after restrictive dieting or a high fever, you might experience telogen effluvium (sudden diffuse hair fall).

Here, the anagen phase is cut short, causing many hairs to enter the telogen (resting) phase simultaneously, resulting in increased hair fall after 3 months during the exogen (shedding) phase. If this constantly happens and isn’t supported with good nutrition, your hair may not grow as long as it used to.

How to Maintain Hair Health During All Four Stages?

Healthy, fuller hair depends on genetics and hormone levels, which are often beyond your control. However, manageable factors like a good lifestyle and proper hair care are essential. Some of the best strategies work across all stages of hair growth are

Balanced Nutrition

Hair is mostly made of protein, so maintaining a good intake of healthy proteins is crucial. This includes lean meats, fish, beans, legumes, and low-fat dairy products. A study in the journal Dermatology and Therapy found that nutrients like Vitamin D, Vitamin C, Iron (especially for women), Zinc, folic acid, and vitamin B12 are all associated with promoting healthy hair growth.

Manage Stress

The Mayo Clinic reports three premature hair-loss conditions related to high stress levels. These include Telogen effluvium, which accelerates hair from the anagen phase into telogen and exogen, doubling or tripling normal daily hair loss. Trichotillomania is a psychological condition causing an irresistible urge to pull hair from your scalp or other parts of your body.

Alopecia areata occurs when the body’s immune system attacks healthy follicles. Learning to de-stress with yoga, meditation, breathing techniques, counseling, and avoiding daily stressors can reduce stress, bringing many positive health benefits.

Appropriate Hair Care

Healthy hair care starts with choosing the right shampoo. Look for products designed for your type of hair, whether it’s oily, dry, fine, color-treated, straight, wavy, curly, or coily. The right conditioner also makes a difference, but finding it might take some trial and error.

Pay attention to how your hair responds to various shampoos and conditioners. Treating your hair gently is key to promoting growth. Avoid hot water when you shampoo and use microfiber towel to dry your hair gently. Hair is more vulnerable to damage when it’s wet, so turning down the heat when drying helps.

Conclusion

The four phases of hair growth include anagen, catagen, telogen, and exogen. Each phase lasts for a different length of time. Maintaining a healthy lifestyle with low stress, a proper diet, and gentle hair care can promote healthy hair for a long time.

If you are losing hair faster than usual, consult a doctor as an underlying condition may be disrupting the stages of hair growth, and treating it promptly can help slow hair loss and preserve the healthy hair you have left.

FAQs

How long is the hair growth cycle?

The duration of the anagen growth phase for the upper lip is typically 16 weeks, while catagen lasts 1 week and telogen lasts 6 weeks. On the scalp, the anagen phase is generally 150 weeks, catagen is 1-3 weeks, and telogen lasts 12 weeks.

How long does a hair shedding cycle last?

The hair shedding (exogen phase) can last about 2 to 5 months. During this time, new hairs are growing in the follicles as old hairs fall away.

What is the 7 year hair cycle?

The most notable growth phase is known as anagen, where individual hair follicles grow for roughly seven years. This period allows the hair to reach its maximum length.

How long is the cell cycle for hair?

Histologically, anagen follicles are long and straight, but angled to permit the hair to lie flat along the body surface. The proliferating matrix cells have a cell-cycle length of approximately 18 hours.