The Hair Growth Cycle Explained: Understanding How Your Hair Naturally Grows

Healthy-looking hair doesn't simply appear overnight—it follows a remarkable biological process that repeats throughout our lives. Every strand of hair on your head is at a different stage of growth, rest or shedding, which is why understanding the hair growth cycle is one of the most important steps in building an effective haircare routine.

In this article, we'll explore how the hair growth cycle works, why daily hair shedding is completely normal, and how maintaining a healthy scalp can help support the environment in which healthy-looking hair grows.

What Is the Hair Growth Cycle?

The hair growth cycle is a continuous process that takes place within each individual hair follicle. Unlike many biological processes that occur simultaneously, every follicle operates independently. This means that each hair on your scalp is at its own unique stage of growth or shedding at any given time (Alonso and Fuchs, 2006).

The average human scalp contains approximately 100,000 hair follicles, each capable of producing hair through repeated growth cycles over many years (Sinclair, 2015).

The cycle consists of four main phases:

• Anagen (Growth)

• Catagen (Transition)

• Telogen (Resting)

• Exogen (Shedding)

Phase 1: Anagen – The Growth Phase

The anagen phase is the active period during which hair is continuously growing.

During this stage:

• Cells within the hair bulb divide rapidly.

• The hair shaft lengthens as new cells are produced.

• Blood vessels surrounding the follicle deliver oxygen and nutrients to support growth.

  
  

For scalp hair, the anagen phase typically lasts between 2 and 7 years, although genetics largely determine its duration (Paus and Cotsarelis, 1999).

The longer a hair remains in anagen, the longer it can grow. This is one reason why some individuals naturally grow very long hair while others find their hair reaches a certain length before shedding.

At any given time, approximately 85–90% of scalp hairs are in the anagen phase (Alonso and Fuchs, 2006).

Phase 2: Catagen – The Transition Phase

After the active growth period ends, each follicle enters the catagen phase.

This short transition stage lasts around 2–3 weeks.

During catagen:

• Hair growth stops.

• The lower portion of the follicle shrinks.

• The follicle detaches from its blood supply.

• The hair becomes what is known as a club hair.

  
  

Only around 1–2% of scalp hairs are in catagen at any one time (Paus and Cotsarelis, 1999).

Although little visible change occurs, this phase is an essential step in preparing the follicle for its resting period.

Phase 3: Telogen – The Resting Phase

Following catagen, the follicle enters the telogen phase.

This is often referred to as the resting stage because active hair production temporarily stops.

The telogen phase generally lasts around 2–4 months (Alonso and Fuchs, 2006).

While the follicle is resting:

• The club hair remains anchored within the scalp.

• New growth gradually begins forming beneath the resting hair.

• The follicle prepares for another cycle of active growth.

Approximately 10–15% of scalp hairs are normally in the telogen phase at any one time.

Phase 4: Exogen – The Shedding Phase

The final stage is exogen, during which the old club hair is naturally released from the follicle.

This is the stage most people notice when they see hairs:

• In the shower

• On their hairbrush

• On their pillow

• Caught in clothing

Losing approximately 50–100 hairs per day is considered a normal part of the hair growth cycle in healthy adults (American Academy of Dermatology Association, 2024).

Importantly, shedding a hair does not mean the follicle has stopped functioning. In most cases, a new hair has already begun developing beneath the shed hair and will continue growing during the next anagen phase.

Why Doesn't All of Our Hair Fall Out at Once?

One fascinating feature of human hair biology is that each follicle functions independently.

If every follicle entered the shedding phase simultaneously, we would periodically lose all of our hair.

Instead, follicles cycle asynchronously, ensuring that while some hairs are shedding, the vast majority are actively growing. This independent cycling helps maintain overall hair density throughout life (Paus and Cotsarelis, 1999).

What Can Influence the Hair Growth Cycle?

Although the hair cycle follows a natural biological pattern, several factors can influence its timing and appearance.

These include:

• Genetics

• Ageing

• Hormonal changes

• Nutritional status

• Physical or emotional stress

• Certain illnesses

• Some medications

• Overall scalp health (Sinclair, 2015)

Temporary disruptions to the cycle can increase the proportion of hairs entering the telogen phase, leading to increased shedding several months after the triggering event. This phenomenon is known as telogen effluvium and should be assessed by a healthcare professional if hair shedding is excessive, persistent or accompanied by other symptoms (Harrison and Sinclair, 2002).

Why Scalp Health Matters

While many people focus on caring for the visible hair shaft, healthy-looking hair begins beneath the surface.

The scalp provides the environment in which hair follicles function. Maintaining a clean, comfortable and well-cared-for scalp can help support the conditions needed for healthy-looking hair.

Good scalp care includes:

• Cleansing regularly to remove excess oil, sweat and product build-up.

• Using products appropriate for your hair and scalp type.

• Avoiding excessive mechanical or heat damage to the hair.

• Following a consistent haircare routine.

Although cosmetic products cannot alter the natural biology of the hair growth cycle, they can help maintain the condition of the scalp and hair, improving the overall appearance and manageability of the hair fibre.

Patience Is Part of the Process

Because hair grows relatively slowly—typically around 1 centimetre (approximately 0.4 inches) per month, although this varies between individuals (Sinclair, 2015)—visible improvements in hair appearance take time.

Healthy haircare is built on consistency rather than quick fixes.

Daily habits that support scalp cleanliness, hydration and overall hair condition are more likely to contribute to healthier-looking hair over time than expecting immediate results from any single product.

Key Takeaways

• Hair grows in four distinct stages: Anagen, Catagen, Telogen and Exogen.

• Around 85–90% of scalp hairs are actively growing at any one time.

• Shedding 50–100 hairs each day is considered a normal part of the hair cycle.

• Every hair follicle operates independently, which prevents all hairs from shedding simultaneously.

• Genetics, age, hormones, stress and overall health can all influence the hair growth cycle.

• A healthy scalp provides the foundation for healthy-looking hair, making consistent scalp care an important part of any haircare routine.

Final Thoughts

Understanding the hair growth cycle helps explain why patience and consistency are so important when caring for your hair. Every strand follows its own natural timeline, and daily shedding is simply one part of a healthy cycle. While no cosmetic product can change the biology of hair growth, maintaining a healthy scalp and caring for your hair with a consistent routine can support the environment in which healthy-looking hair grows.

At Bloom & Root, we believe beautiful hair starts where you can't see it—beneath the surface. By combining science-led formulations with thoughtful scalp care, we're committed to helping you build healthy habits that support healthier-looking hair over time.

References

Alonso, L. and Fuchs, E. (2006) 'The hair cycle', Journal of Cell Science, 119(3), pp. 391–393. Available at: https://doi.org/10.1242/jcs.02793

American Academy of Dermatology Association (2024) Do you have hair loss or shedding? Available at: https://www.aad.org/public/diseases/hair-loss/insider/shedding (Accessed: 30 July 2025).

Harrison, S. and Sinclair, R. (2002) 'Telogen effluvium', Clinical and Experimental Dermatology, 27(5), pp. 389–395. Available at: https://doi.org/10.1046/j.1365-2230.2002.01080.x

Paus, R. and Cotsarelis, G. (1999) 'The biology of hair follicles', New England Journal of Medicine, 341(7), pp. 491–497. Available at: https://doi.org/10.1056/NEJM199908123410706

Sinclair, R. (2015) Hair: From Physiology to Pathophysiology. Berlin: Springer.