Have you ever wondered why your hair grows, stops growing, and eventually falls out?

Hair growth is a continuous process that happens beneath the surface of your scalp. Every strand goes through its own natural cycle of growth, transition, rest, and shedding.

Understanding how this process works can help you better understand normal hair shedding, changes in hair thickness, and why certain factors can affect the appearance of your hair.

Let's take a closer look at the structure of your hair and the four main stages of the hair-growth cycle.

Understanding the Structure of Hair

What you see above your scalp is only one part of a hair. Each strand is connected to structures beneath the skin that support its growth.

The Hair Bulb

At the bottom of each hair follicle is the hair bulb, where new hair cells are produced.

Cells within the bulb continually divide and develop, eventually pushing older cells upward and out through the scalp. This process is what allows your hair to grow.

The hair bulb also contains melanocytes, which produce the pigment responsible for your natural hair color.

The shape of the follicle can also influence the characteristics of the hair that grows from it, including whether the strand appears straight, wavy, or curly.

The Hair Root

The hair root is the portion of the hair located underneath the skin.

It sits inside the hair follicle and connects with structures that support hair growth, including blood vessels, nerves, muscles, and sebaceous (oil) glands.

The follicle provides the environment needed for the hair-producing cells to receive nutrients and continue developing.

The Hair Shaft

The hair shaft is the visible portion of your hair — everything that extends above the surface of the scalp.

It is primarily made from keratin, a strong structural protein that is also found in nails.

The shaft has several layers:

Cuticle:
The outer protective layer. It consists of overlapping cells that help protect the inner portions of the strand and influence smoothness and shine.

Cortex:
The main structural layer of the hair. It contains keratin fibers and much of the pigment that gives your hair its color. The condition of the cortex has a major influence on the strength and appearance of the strand.

Medulla:
The innermost layer. It is more commonly found in thicker or coarser hair and may be absent in some fine hair types.

Together, these structures determine many of the physical characteristics of your hair.

The Four Stages of the Hair Growth Cycle

Your hair isn't continuously growing at the same rate. Instead, individual hairs move through a repeating cycle.

The four commonly described stages are anagen, catagen, telogen, and exogen.

1. Anagen — The Growth Stage

Anagen is the active growth phase of the hair cycle.

During this stage, cells within the hair follicle are rapidly producing new hair. As new cells form, older cells are pushed upward, allowing the hair shaft to extend beyond the scalp.

This is typically the longest stage of the cycle and can last for several years.

At any given time, most of the hairs on your scalp are normally in this active growth phase.

How long a person's anagen phase lasts can vary considerably and is one reason why hair-growth length differs from person to person.

2. Catagen — The Transition Stage

After the active growth period, the follicle enters a short transitional phase known as catagen.

During this stage, hair growth slows and the follicle begins to shrink. The hair becomes separated from the active growth structures within the follicle but generally remains attached to the scalp.

Catagen is relatively brief compared with the other stages and usually lasts only a few weeks or less.

3. Telogen — The Resting Stage

Telogen is the resting phase of the hair cycle.

During this period, the follicle is relatively inactive while it prepares for the next growth cycle. The existing hair remains in place while a new hair begins developing within the follicle.

This stage generally lasts for several months.

Because individual hairs don't all enter telogen at the same time, your entire scalp doesn't stop growing hair at once.

4. Exogen — The Shedding Stage

Exogen is the stage in which an older hair is released and eventually falls from the scalp.

Some daily shedding is completely normal. Many people naturally lose dozens of hairs throughout the day, particularly while washing, brushing, or styling their hair.

At the same time that an old hair is being shed, a new hair may already be developing within the same follicle, allowing the cycle to begin again.

Why Does the Hair Growth Cycle Matter?

The hair-growth cycle is a natural process, but it can be influenced by a variety of factors.

Stress, illness, nutrition, hormonal changes, genetics, certain medications, and some scalp or medical conditions can affect how the cycle functions.

For example, a greater number of hairs entering the resting or shedding stages at the same time can result in noticeably increased hair shedding.

Changes in the growth cycle can also contribute to the appearance of thinning hair.

Supporting a Healthy Hair-Growth Cycle

While you can't control every factor that affects your hair, maintaining healthy everyday habits can help support your overall hair and scalp health.

Consider:

• Eating a balanced, nutrient-rich diet

• Getting adequate sleep

• Managing ongoing stress

• Avoiding excessive heat styling

• Limiting harsh chemical treatments

• Being gentle when brushing and washing

• Avoiding hairstyles that place excessive tension on the hair

• Keeping your scalp clean and cared for

• Choosing hair-care products suited to your hair type

For people experiencing persistent thinning or pattern-related hair loss, treatments containing clinically studied ingredients such as minoxidil may also be an option worth discussing with a healthcare professional.

Your Hair Is Always Changing

Hair growth isn't a straight-line process. Every strand on your scalp is moving through its own individual cycle, which means some hairs are growing while others are resting or shedding.

A certain amount of daily shedding is therefore a normal part of maintaining your hair.

However, significant changes in shedding, noticeable thinning, receding areas, or bald patches may indicate that something is affecting the normal hair cycle.

At Hair Grow Australia, we believe understanding how your hair works is an important part of taking better care of it.

Learn how your hair grows, look after your scalp, and build healthy habits that support your hair from root to tip.

This article is provided for general educational purposes and is not intended to diagnose or treat hair loss or any medical condition. If you experience sudden, severe, or unexplained hair loss, consult a qualified healthcare professional.