Hair life cycle

The structure and growth of hair are considerably more complex than they appear at first glance. They are tough, yet flexible. Washing and caring for them takes quite a bit of time, but we still adore them. They grow and fall out. Despite this being a repetitive process, in this blog we will try to shed light on how hair actually grows.
The tissues in our body are constantly regenerating, but except in childhood and youth, they no longer grow. In contrast, hair is constantly growing. Just like other tissues in the body, hair is subject to a cycle of growth, hibernation, and death.

How does hair grow?

Hair is essentially a strand of hair on the scalp made of keratin, which forms a hard protein. Hair follicles are located in the hypodermis and dermis, containing protein cells. To simplify, the system of blood vessels supplies these follicles with all the necessary nutrients for hair growth. The hair follicles are also surrounded by sebaceous glands, which provide hair with natural shine and softness.
Hair growth consists of four phases.
The first in the series of phases is the anagen, or growth stage, followed by the catagen phase, or transitional phase, when growth slows down, the third phase is the telogen, or resting/hibernation phase. The last phase is the exogen phase, or shedding phase. These cycles last for several years, and up to 20 hairs grow from each follicle during a lifetime.

1. Anagen phase

The anagen phase is the longest phase of hair growth, lasting from two to up to eight years. Several factors influence it, and these factors also determine the length of the hair strand. During this time, hair proteins and fibers are formed in the follicle. In this phase, hair grows approximately one centimeter per month, and on average, 80-90% of the total hair length grows during this period. As we age, the anagen phase shortens, and consequently, hair growth slows down. Between 75-85% of all hair is in the anagen phase.
The incorrect establishment of the anagen phase can be influenced by possible negative factors such as chemotherapy, oral contraceptives, chronic inflammation, and certain medications and chemicals. In most cases, after therapy or treatment is completed, the anagen phase is re-established.

2. Catagen phase

After the anagen phase, hair growth enters the catagen phase. In this phase, the follicle shrinks to one-sixth of its original size. Despite the hair stopping receiving nutrients and partially detaching from the follicle, it does not fall out. This phase, also called the transitional phase, lasts about 4 to 6 weeks and usually involves approximately 2% of the hair on the scalp in the cycle.

3. Telogen phase

After the catagen phase, the resting phase, or telogen phase, begins. The hair is already completely separated from the hair follicle and consequently from nutrients. In this phase, new hairs begin to emerge from the hair roots, pushing the previously grown hair towards the surface. On average, it lasts 3-5 months. Approximately 15-18% of all hair on the head is in the telogen phase in the entire cycle.
Premature transition to the telogen phase is often influenced by mental or physical stress, hormonal imbalance as a result of pregnancy or menopause, and protein deficiency.

4. Exogen phase