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Hair Growth Cycles

The Structure of Hair

Hair contains two recognizable parts – the follicle and the shaft. The follicle is the region of hair growing from within the scalp while the shaft is the part visible outside the scalp.

The Follicle

There are various layers within the follicle, each with a different function. The papilla is composed of capillaries (the thinnest blood vessels in the body), which are found at the bottom of the tissue. In addition to maintaining the health of living cells surrounding the papilla, these blood vessels also provide oxygen to them. A bulb in the hair is a living part that has cells that multiply exceptionally quickly compared to any other part of the body.

Sebaceous glands are directly beneath follicle muscles. Muscle contractions produce sebum (natural skin oil). The sebum secreted by this gland ensures healthy hair growth and prevents hair loss, making it a vital part of the hair follicle.

The Shaft

The shaft is made of keratin, a protein, and contains 3 separate parts namely the inner, middle and outer layers. The visible part of the hair is made up of dead cells, which is why keratin is a derivative of dead cells. A medulla is a component of the inner layer, a cortex is a component of the middle layer, and a cuticle is a component of the outer layer. Cortex and medulla pigments impart color to hair.

What are the Different Stages of Hair Growth?

Hair growth is a complex process that involves the cyclic activity of hair follicles. The hair growth cycle consists of three phases: anagen, catagen, and telogen.

Anagen Phase

The anagen phase is the active growth phase of the hair follicle. During this phase, the hair grows rapidly (approximately half an inch per month), and the follicle is nourished by blood vessels. The length of the anagen phase varies depending on the location of the hair on the body, with scalp hairs having the longest anagen phase lasting up to 6 years.

Catagen Phase

The catagen phase is the transition phase between the anagen and telogen phases. During this phase, the hair follicle shrinks, and the hair stops growing. This phase lasts for about two weeks.

Telogen Phase

The telogen phase is the resting phase of the hair follicle. During this phase, the hair is released from the follicle and falls out, causing hair loss. This phase of hair loss lasts for about three months before the hair cycle restarts again.

The hair growth cycle is influenced by various factors, including genetics, age, hormonal changes, and environmental factors. Understanding the hair growth cycle can help in the development of hair loss treatments and hair restoration techniques.

Why Does the Hair Cycle Get Disrupted?

The hair cycle gets disrupted, causing damaged hair and hair loss due to the following:

Poor Diet and Nutrition

An inconsistent and unbalanced diet can cause disruptions to the hair cycle and aggravate hair loss. In order to solve this issue, it is recommended that you keep a consistent and healthy balanced diet with sufficient nutrients such as vitamins, iron, fiber and proteins. If you feel that this is not enough, you can also consider adding supplements containing these nutrients.


The buildup of stress can increase the periods of time in the hair cycle where new hair is not growing, increasing the overall hair loss during these periods. Managing and dealing with stress ensures the growth of hair and reduces the risk of hair loss.

Why Does Hair Loss Occur?

There are various reasons why hair loss can occur.

One of the most common causes of hair loss is genetics. Male and female-pattern baldness, also known as androgenetic alopecia, is an inherited condition that affects many people. According to a study published in the Journal of Investigative Dermatology, androgenetic alopecia is caused by a combination of genetic and environmental factors.

Another reason for hair loss could be hormonal changes. Pregnancy, menopause, and thyroid disorders are some examples of hormonal imbalances that can lead to hair loss. The hormone dihydrotestosterone (DHT) is also known to cause hair loss in individuals with a genetic predisposition to androgenetic alopecia.

Certain medical conditions may contribute to hair loss. Autoimmune diseases such as alopecia areata and lupus can cause hair loss. Scalp infections, such as ringworm, can also lead to hair loss. Chemotherapy and radiation therapy used to treat cancer may be another cause, as the drugs damage hair follicles.

Lastly, we can factor in possible nutritional deficiencies that lead to hair loss. Iron deficiency anemia, for example, can cause hair loss. A study published in the Journal of Korean Medical Science found that low levels of vitamin D are associated with hair loss in women.

How can we ensure hair growth and overcome hair loss?

Hair loss can be a frustrating and distressing experience, but there are ways to promote hair growth and reduce hair loss. Here are some tips:

Maintain a healthy diet

In order to prevent hair loss, it is important to consume a well-balanced diet that is high in proteins, vitamins, and minerals. Foods like eggs, nuts, salmon, spinach, and sweet potatoes are all excellent options for preventing hair loss.

Use hair growth products

You can find a variety of hair growth products available on the market today such as shampoos, conditioners, and serums that will enhance the growth of your hair. Look for products that contain ingredients such as biotin, keratin, and caffeine, which are known for their hair loss prevention properties.

Massage your scalp

Taking a few minutes every day to gently massage your scalp can help increase blood flow to your scalp, which can promote hair growth and reduce the risk of losing your hair. Use your fingertips to gently massage your scalp for a few minutes at a time each day.

Manage stress

It is important to manage stress levels in order to prevent hair loss, so it's important that you exercise, meditate, and breathe deeply in order to reduce the levels of stress you are under.

Consult a Scalp Specialist

If you're experiencing significant hair loss, it's a good idea to consult an established scalp specialist who can identify the underlying cause of your hair loss and recommend appropriate treatments.

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