Understanding the hair growth cycle is essential for people trying to reverse hair thinning and loss. While there are several different theories on how to decrease hair loss and increase hair growth, one thing is constant: increasing your hair thickness and length requires that you keep your hair in the growing phase of the growth cycle. Yet, many of our behaviors and some hair conditions can shorten or even stop the growth phase, leaving us with thinning heads of hair. Your ultimate guide to hair growth cycles is here to help you better understand how your hair grows so you can have healthier, thicker hair.
The Anatomy of Hair
Knowing the anatomical structure of hair is a great starting point for helping you better understand the hair growth cycle. There are two major components to hair: the hair follicle and the hair shaft.
The hair follicle is what anchors a single hair into the scalp. The follicle is comprised of the papilla and the bulb, which lie beneath the surface of the scalp. The bulb is where new cells grow around the hair follicle to make it longer while the papilla supplies blood to the follicle. Blood supply is crucial to hair growth as it delivers oxygen and nutrients that help hair grow.
The hair shaft is your hair. Essentially, hair is made up of the protein keratin, which is encapsulated in a protective layer called the cuticle. We have thousands of hair shafts on our heads, and they do not all grow at once. Thus, it is normal to lose hair each day (between 50-100) and not notice a significant change in our hair thickness.
Several other structures and processes support hair growth as well. For example, sebaceous glands are oil glands in the skin that play an important role in nourishing and hydrating the hair. And hair growth is not limited to what is happening on and in your scalp: hair growth can be affected by other things in your body, including hormones and stress.
The Hair Growth Cycle
Three phases make up the hair growth cycle: anagen, catagen, and telogen. Generally, each phase lasts a specific amount of time under normal conditions. However, disruptions to the growth cycle can leave you with thinner, shorter, and more brittle strands. Furthermore, each strand of hair is in its own hair growth cycle, meaning that not all of the hairs on your head will fall out at once - phew! Let’s take an in-depth look at each phase of the hair growth cycle.
The Anagen Phase
Anagen is the growing phase of the hair growth cycle. During this phase, cells in the bulb rapidly divide to create new hair growth. This phase lasts anywhere between 2-7 years on average before the follicles become dormant. The longer the phase lasts, and the less your cut your hair, the longer your hair will grow. Most hair shafts can grow between 18-30 inches depending on how well your care for your hair and body. Generally, your genetics, age, overall health, and hair habits determine the length of anagen.
Several things can disrupt the anagen phase. For example, telogen effluvium is a condition that forces many hair follicles out of the anagen phase. In this condition, a stressful event like surgery, loss of a loved one, illness, and childbirth precipitates temporary hair loss. Additionally, conditions like androgenic alopecia shorten and suppress the anagen phase, leaving people with thinning part lines, receding hairlines, and balding crowns.
The Catagen Phase
The growing phase in each hair follicle eventually must stop, as growing new and healthy hair strands is essential. Thus, after the anagen phase, hair follicles switch to catagen, a short transitional phase where growth ceases. Compared to the long anagen phase, catagen lasts only about 2-3 weeks. During this phase, the hair begins to detach itself from the blood supply. At this point, it is called a club hair. Typically, club hairs are your longest hairs as they have finished the growing phase and are preparing to shed. Yet, cellular activity within the bulb keeps the hair intact on your head until new hair eventually pushes the club hair out.
The Telogen Phase
Finally, hair enters the resting phase, or telogen. While this phase is considered a “resting” phase, it is actually a very active phase for the bulb as it is preparing a new hair shaft. Telogen lasts about three months and is the phase where the club hair is essentially waiting to fall out. Once new hair comes through the follicle, it pushes the club hair out, causing shedding. Some hair growth cycles classify the actual shedding event as a fourth phase of the hair growth cycle. Exogen lasts only a day or two and marks the end of the hair growth cycle.
About 10% of your hairs are in telogen at any point in time. However, most people do not notice normal hair shedding because 80-90% of hair is consistently in the anagen phase. Shedding can become noticeable in certain situations, like telogen effluvium. In this condition, some stressful trigger forces more hair than normal into the telogen phase. Thus, people tend to notice a significant increase in hair shedding about three months after a stressful event. While it is normal to lose between 50-100 hairs a day, people with telogen effluvium can lose up to 300 hairs a day. With time, hair eventually goes back to its original thickness after telogen effluvium, but the condition can be startling.
How To Support The Hair Growth Cycle
If you want longer, thicker, healthier hair, the goal is to keep your hair in the anagen phase as long as possible. People with hair loss usually have fewer follicles in the anagen phase, and some conditions even shorten the anagen phase altogether. For example, people with male or female-pattern baldness struggle with hair loss likely related to genetics. In this condition, a form of testosterone called DHT shortens the anagen phase and shrinks the hair follicles, which eventually produce finer, shorter strands of hair. Knowing what is causing your hair loss is a great starting point for figuring out solutions to keep your hair in anagen for as long as possible.
To keep your hair in a long and healthy anagen phase, try to implement the following:
Reduce stress. We have discussed how stress can cause your hair to switch from actively growing to the resting phase. Therefore, keeping your stress levels at a minimum is essential for keeping as many strands as possible in the growing phase. Additionally, stress over long periods of time can lead to chronic inflammation and other health conditions that can indefinitely suppress hair growth.
Eat a healthy diet. The foods we eat impact every cell in our bodies, including our hair. Make sure your diet is rich in proteins, healthy fats, vitamins, minerals, and antioxidants.
Take a hair growth supplement. A supplement specifically designed for hair health can ensure you get the nutrients your hair needs to grow.
Be kind to your hair. Harsh styling treatments and chemicals can take a toll on hair in the anagen phase. Try to avoid using chemicals, hot styling tools, and hairstyles that pull on your follicles.
- Use products that fight hair loss. Technology has rendered incredible new products that suppress DHT's effects in people with androgenic alopecia and prevents hair loss from telogen effluvium.
If you are struggling with hair loss, shop the entire line at DS Laboratories for products that will prolong the anagen phase of the hair growth cycle.