Understanding Hair Growth


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Growth cycles

The three stages of hair growth are the anagen, catagen, and telogen phases. Each strand of hair on the human body is at its own stage of development. Once the cycle is complete, it restarts and a new strand of hair begins to form. The rate or speed of hair growth is about 1.25 centimeters or 0.5 inches per month, or about 15 centimeters or 6 inches per year.

Anagen phase

The anagen phase is known as the growth phase. It begins in the papilla and can last from two to six years. The span at which the hair remains in this stage of growth is determined by genetics. The longer the hair stays in the anagen phase, the faster and longer it will grow. During this phase, the cells in the papilla divide to produce new hair fibers, and the follicle buries itself into the dermal layer of the skin to nourish the strand. About 85% of the hairs on one's head are in the anagen phase at any given time.

Catagen phase

Signals sent out by the body determine when the anagen phase ends and the catagen phase begins. The catagen phase, also known as the transitional phase, allows the follicle to, in a sense, renew itself. During this time, which lasts about two weeks, the hair follicle shrinks due to disintegration and the papilla detaches and "rests," cutting the hair strand off from its nourishing blood supply. Ultimately, the follicle is 1/6 its original length, causing the hair shaft to be pushed upward. While hair is not growing during this phase, the length of the terminal fibers increases when the follicle pushes them upward.

Telogen phase

During the telogen, or resting, phase the follicle remains dormant anywhere from 1–4 months. Ten to fifteen percent of the hairs on one's head are in this phase of growth at any given time. In this phase the epidermal cells lining the follicle channel continue to grow as normal and may accumulate around the base of the hair, temporarily anchoring it in place and preserving the hair for its natural purpose without taxing the body's resources needed during the growth phase.

At some point, the follicle will begin to grow again, softening the anchor point of the shaft initially. The hair base will break free from the root and the hair will be shed. Within two weeks the new hair shaft will begin to emerge.

The anagen phase begins again once the telogen phase is complete. The process results in normal hair loss known as shedding.





Anagen: The Growth Stage

The first stage of hair growth is the Anagen Stage. This is the stage of the cycle where new hair is produced. Approximately 85% of all the hair on the body will be in the growth stage at one time. Since most of the hair on the body is in the Anagen Stage at the same time, it makes it the perfect time in the hair growth cycle to wax.

Catagen: The Regression or Falling Out Stage

The Catagen Stage is the second stage in the hair growth cycle. In this stage, the hair shaft grows upward and detaches itself from the bulb. Once the hair has detached itself from the bulb, its also gets cut off from the blood supply. This means that the hair no longer receives any nutrients or pigment. This is the mean reason why hair in this stage looks dull and unhealthy. Only 2 to 3% of the body's hair will be at this stage at any given time.

Telogen: The Final or Resting Stage

This is the stage in the hair growth cycle when hair is at its fullest size. In this stage, hairs are completely erect in the follicle, allowing the hair to show above the skin's surface. Hair is more likely to either shed or fall out during this stage. Only 15% of the body's hair will be in this stage at any given time.

Fun Fact about Hair Growth: It takes anywhere from 4 to 13 weeks for the hair to grow from the dermal papilla (the base of the hair follicle) to the surface of the skin. Have you ever felt a little leftover stubble after getting waxed? That's because some of the hairs left behind were still in the early Anagen Stage and not long enough to be removed from waxing. With regular waxing every 3 to 4 weeks, you are more than likely to get your hair on the same growing cycle, allowing for optimal waxing results.



Miniaturization is the technical term given to the shortening of the Anagen phase of the hair growth cycle. For many people the length of the Anagen phase shortens every cycle resulting in hair growing slower, becoming weaker and appearing less vibrant.

Many treatments work by increasing the duration of the Anagen phase or reducing the resting phase.

Excessive hair shedding

When the hair enters the resting phase early it results in excess shedding and ultimately noticeably thinning hair. This does not become apparent until approximately 50% of hairs have been shed. This is because each hair is in a different stage of the hair growth cycle which can take years.

It is normal to shed around 100 hairs per day so identifying excessive shedding is difficult. Most people notice more shed hairs than normal when washing their hair, on their pillow in the morning or when brushing their hair.

A wide range of factors can impact on the health of the hair, hair shedding and hair growth. These factors can prevent the body from efficiently absorbing the essential nutrients from food and are often lifestyle related.

What influences healthy hair growth

There are many factors which influence healthy hair growth; these encompass a whole range of medical, emotional and lifestyle conditions which can prevent the body from effectively absorbing the essential nutrients it needs to support healthy hair.



In our twenties and thirties we typically have 615 hair follicles per square centimetre. The number falls to 485 by the time we hit fifty and to 435 at eighty. Each hair also becomes thinner therefore reducing hair volume.


Believe it or not, the cliché about stress leading to hair problems is actually true. In extreme stress, the adrenal gland goes into overdrive, and the resultant increase in adrenaline sometimes leads to a consequent increase in the production of testosterone and dihydrotestosterone which, without enough estrogen to counterbalance it, can lead to hair not being as healthy as it should be.

For some people being stressed can seriously affect the condition of their hair and it can turn into a vicious circle: stress affects the hair cycle and the impact of this can cause a lot of stress for the sufferer.

Hair can suffer between four and sixteen weeks after the stress trigger has occurred. It can be difficult to pinpoint a specific stress episode as the reason why hair becomes unhealthy but it is often acute and chronic stress that will bring on conditions such as telogen effuvium (hair shedding) and alopecia areata (patchy hair loss).

For many, it is a soul destroying experience intruding into every part of daily life and leading to anxiety, distress and a dramatic loss of self–esteem. So it is important to do all you can to help alleviate the problem. Try to include these simple and effective ways to reduce stress in your life; exercise, think positively, stay flexible with your plans and get enough sleep.


In some instances medicines may have side effects which impact on healthy hair growth.

Poor diet

A diet rich in protein, vitamins and minerals is essential for healthy hair and hair growth. A diet low in protein is often the reason why someone will experience hair loss, as a poor diet affects new growth. The hair follicle is a non essential tissue and, therefore, one of the last tissues to receive nutritional substances. Any long-term deficiencies may lead to premature hair problems.

Diet tips: Eat at least 5 ounces (approximately 150 grams) of protein a day. Foods high in protein are meat, chicken, fish, beans, eggs, cheese and tofu. Because hair is made of 80% to 95% protein, this is an important area of your diet. Iron deficiency is a major cause of hair loss especially in women or men who are vegetarian. If you are iron deficient or anaemic, then taking iron could be helpful for your hair. Other important minerals for healthy hair functioning are: zinc found in seafood and cereals, silica found in potatoes, red and green peppers and bean sprouts, magnesium found in green vegetables and nuts and essential fatty acids such omega fatty acids found in fish.

Hormonal change

Hormonal changes associated with menopause can affect the healthy hair growth cycle. While this menopausal side effect is relatively rare, it has been known to occur in some cases. Other hormonal changes in the body - notably thyroid issues and hormonal responses to changes in the autoimmune system have been known to affect hair growth in some women. Women can experience problems with their hair due to a hormone imbalance and increased sensitivity to the male hormones we all have.

Post pregnancy

While a beautiful and natural process, pregnancy is nonetheless stressful for the body. Consequently, it is common for post-partum hair shedding or even bald patches to occur as hormone levels get back to normal. This is usually a temporary and reversible condition, but If hair health is still an issue a few months after the pregnancy is over, it is likely that the hair condition is attributed to something other than the pregnancy.

Birth control

The pill is the most common form of contraception in women; a mixture of progesterin and estrogen carries an occasional side-effect which affects healthy hair growth in those who have a hereditary medical history of hair growth problems.


Aerosol sprays, hair dyes, straightening irons, and curlers might seem to be essential to hair beauty in the short term, but excessive use of may result in damaging hair in the long run. Women who find their hair healthy is being affected may also want to consider what they’re putting onto their hair and scalp on a daily basis and consider other cosmetic methods and nutritional supplements.


Smoking affects healthy hair growth. Cigarette smoking has been shown to cause poor circulation, which can affect the amount of blood flow available to the hair follicles of the scalp.


Poor hair health commonly takes one of the following forms:

Telogen Effluvium is the name given to temporary hair thinning from any area of the scalp and is common post pregnancy, after a period of stress or hormonal changes or as a result of poor diet. The hair follicles are interrupted, go into a resting phase and stay that way for months. After that hair tends to fall out in chunks, which is frightening to many people. The good news is that in most cases telogen effluvium is temporary and the hair growth will eventually return to normal. Women suffer from this more than men because one of the causes are the hormonal changes of childbirth or hormonal changes that result from stopping oral contraceptives. Some women may find that their hair drops out three months after giving birth, but usually returns to normal about a year later. Other causes of telogen effluvium can be major surgery, crash diets, hypo or hyper thyroidism, infections or other physical or mental traumas like being involved in an accident, the death of a loved one or even divorce. Medications that cause telogen effluvium are often blood thinners or drugs that treat high cholesterol.

Traction Alopecia is caused by excessive pulling or stressing of the hair strand at the root and is often seen in women with tight braiding.

Trichotillomania is an anxiety disorder where sufferers pull out their hair. When the need to pull becomes too great the sufferer will pull on the hair strand until the hair is tugged out at the root. It’s seen often in children, girls and women, who pull out hair from specific places on their scalp. Sometimes sufferers will also pluck out the hair of their eyebrows and their eyelashes.