What Are the 4 Stages of the Hair Growth Cycle?

Ever wondered about the common hair issues you’ve encountered but couldn’t quite pinpoint their causes? To truly understand these issues, it’s essential to delve into the basics: the stages of the hair growth cycle. 

This cycle is a dynamic process that every strand of hair undergoes, influencing its length, strength, and overall health. By comprehending these stages—from active growth to shedding—you’re bound to uncover the key factors that affect our hair’s appearance and health. 

So, what are the different phases of this intricate journey that your hair undergoes to maintain its vitality and resilience?

1. Anagen Phase: The Growing Phase

The Anagen Phase marks the beginning of the hair growth cycle, known as the “Growing Phase” or “Active Phase.” During this stage, hair follicles are at their most active, with cells in the hair root rapidly dividing to produce new hair cells. This phase is crucial as it determines the length and strength of our hair strands.

• Definition and Duration of the Anagen Phase: The Anagen Phase varies in duration depending on factors such as genetics, age, and overall health. Typically, scalp hair remains in the Anagen Phase for about two to eight years, although some individuals may experience longer or shorter phases. However, when it comes to hair follicles residing in other areas of the body, like the eyebrow, they tend to have a much shorter Anagen Phase, lasting only for a couple of months, around two to three to be more specific.
• Activities of Hair Follicles During This Phase: During the Anagen phase, hair follicles are actively producing hair shafts that continue to grow until they are either cut or naturally shed. The rapid cell division in the hair root results in visible hair growth from the scalp or other parts of the body where hair is present.
• Percentage of Hairs in the Anagen Phase at Any Given Time: Approximately 90% of the hair on your scalp is in the Anagen Phase at any given time. This high percentage underscores the active growth state that our hair follicles are typically in, ensuring continuous hair growth and renewal.

2. Catagen Phase: The Transition Phase

Right after the Anagen Phase is the Catagen Phase in the hair growth cycle, representing a transitional period between active growth and rest. During this phase, significant changes occur within the hair follicles as they prepare for the next stage of the cycle.

• Definition and Duration of the Catagen Phase: The Catagen Phase is a brief stage lasting about two weeks. Marking the transition from active hair growth to a resting state, during this time, the hair follicle undergoes structural changes and separates from the dermal papilla, which supplies nutrients necessary for hair growth.
• Changes in Hair Follicles During This Phase: Hair follicles in the Catagen Phase regress and shrink. This process involves apoptosis, or programmed cell death, in the lower part of the hair follicle. The detachment from the dermal papilla disrupts the hair’s nutrient supply, leading to the formation of what is known as a club hair.
• Percentage of Hairs in the Catagen Phase at Any Given Time: Only about 3% to 5% of all hairs tend to be in the Catagen Phase at any given time. This small percentage reflects the relatively short duration of this phase compared to the Anagen Phase, where the majority of hair follicles are actively growing.

3. Telogen Phase: The Resting Phase

The Telogen Phase is the third stage of the hair growth cycle, commonly referred to as the “Resting Phase.” During this period, hair follicles are in a state of dormancy, where hair growth ceases temporarily before the cycle recommences.

• Definition and Duration of the Telogen Phase: The Telogen Phase typically lasts around two to three months. Since this phase is characterised by hair follicles being in a resting state, it basically means that there is no active growth occurring during this time. Instead, old hairs remain in place while new hairs begin to form at the base of the follicle.
• Characteristics of Hair Growth During This Phase: Since hair growth is dormant during this phase, the focus shifts from active production to maintaining the hair in its current state. This phase allows the follicles to rejuvenate and prepare for the next cycle of growth. Plus, hair shafts that enter the Telogen Phase are at the end of their lifespan and will eventually be shed to make way for new hair growth.
• Percentage of Hairs in the Telogen Phase at Any Given Time: Approximately 9 to 15% of scalp hairs are in the Telogen Phase at any given time. 

4. Exogen Phase: The Shedding Phase

The Exogen Phase represents the final stage of the hair growth cycle, often referred to as the “Shedding Phase.” During this period, individual hair strands are naturally released from the hair follicles to make way for new growth.

• Definition and Duration of the Exogen Phase: The Exogen Phase is where hair shedding occurs as old hairs are actively released. This phase typically lasts between two to five months, allowing new hairs to begin growing in the follicles that have shed their old hairs.
• Process of Hair Shedding During This Phase: Hair shedding during the Exogen Phase is a natural process where individual hairs detach from the hair follicles. This shedding process is essential for the renewal of the hair growth cycle.
• Normal Rate of Hair Loss During the Exogen Phase: Not to be confused with hair loss, hair shedding would be considered normal to shed or lose between an average of 50 and 100 hairs daily during this phase. Besides that, factors such as regular hair care practices, including brushing and washing, can influence the rate of shedding.

Factors Affecting Hair Growth

• Genetic and Hormonal Influences: Genetics play a significant role in determining hair growth patterns, including hair texture, colour, and susceptibility to conditions like pattern baldness. Fluctuations in hormones, such as those occurring during puberty, also impact hair growth cycles by affecting follicle activity.
• Lifestyle Factors Such as Nutrition and Stress Levels: Nutrition rich in essential vitamins, minerals, and proteins supports healthy hair growth. Conversely, poor diet choices can lead to hair thinning and loss. Stress, both physical and emotional, can disrupt hair growth cycles, leading to temporary shedding or even prolonged hair loss conditions.
• Importance of Proper Hair Care in Maintaining Healthy Hair Growth: Effective hair care practices, including regular washing with suitable products, conditioning, and avoiding excessive heat or chemical treatments, are vital for maintaining hair health. Proper care nourishes the scalp and follicles, promoting optimal conditions for hair growth and minimising damage that can lead to breakage or loss.

Understanding the root causes of hair loss and adopting proper hair care practices are crucial steps towards maintaining healthy hair growth. So, whether you’re considering hair transplant options or exploring non-invasive hair growth treatments, consulting with a qualified hair specialist can provide invaluable insights and guidance on the most suitable path forward for your hair health journey.