The hair growth cycle Copy

Hair Growth Cycle

Hair follicles grow in repeated cycles. One cycle consists of three phases:

Each hair passes through the phases independent of neighbouring hairs.

Hair Growth Facts:

• The average person loses around 100 hairs a day as part of their growth cycle.
• Can be affected by medical conditions (e.g. serious illness)
• Hair can stop growing during illness and may become weaker in structure
• Is changed during pregnancy no hair goes into the catagen stage of the cycle.
• Hair grows on average 1.25cms a month
• Hair, on the head, has a life cycle of between 2 and 7 years
• Individual characteristics are often hereditary
• Hair is elastic and can stretch 1.5 times its own length when wet
• A single hair can support a weight of 50 to 80gms
• People with fine hair tend to have a less than average growth rate and a shorter life cycle
• People with coarse hair tend to have a more than average growth rate and a longer life cycle

Anagen Phase

Approximately 85% of all hairs are in the growing phase at any time. This growth phase can vary from 2 years to six years. Hair will grow approximately 10cm per year, and any individual hair is unlikely to grow more than one meter long.

In the anagen stage, the hair receives nourishment from the blood supply from the dermal papilla. This enables the cells to reproduce. Cells move upwards to form the different structures of the hair shaft. Melanin is also produced to form the hair colour.

Catagen Phase

This is the transitional phase that follows the growth phase. The catagen phase lasts around one to two weeks. During the catagen phase, the hair follicle shrinks to about 1/6 of the normal length. The lower part is destroyed, and the dermal papilla breaks away to rest below.

This is the inactive or resting stage of hair growth. In this stage, the dermal papilla breaks away to make the lower end of the hair become loose from the base of the follicle. The hair is still being fed from the follicle wall and is sometimes known as club-ended hair. The hair starts to become drier and continues to move up to just below the sebaceous gland. At this stage, it can be easily brushed out.

Telogen Phase

This resting phase follows the catagen phase and lasts around five to six weeks. During this time, the hair does not grow but stays attached to the follicle whilst the dermal papilla stays in a resting phase below. Around 10-15% of hairs are in this phase at any time.

The hair follicle re-enters the anagen phase. The dermal papilla and the base of the follicle join together again, and a new hair begins to form. If the old hair has not yet been shed, the new hair pushes the old one out, and the growth cycle starts over again.

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