Hair is composed of Keratin, a special protein that also produces our fingernails and toenails the nails and forms the protective outer layer of our skin. Each strand of hair consists of three concentric layers, the cuticle, the cortex and the medulla.

The outer layer is called the cuticle and is thin and colorless, its job is to protect the thicker cortex which contains the melanin. Melanin is responsible for the color of your hair and the actual color depends on what kind of melanin you have . There are two kinds, eumelanin which creates brown or black hair, and pheomelanin which makes hair appear red. Blonde hair is a result of very low amounts of melanin, the shade of the blonde again depends upon which type of melanin you have. Gray hair is a result of a lack of melanin which is often caused by age but can also be caused by stress and illness.

The innermost layer of hair is called the medulla and reflects light giving hair the various color tones it has. That's why hair color looks a lot different in sunlight than it does in the shade.

Whether you have straight or curly hair depends on the shape of the cortex. If the cross section of the cortex is round you will have straight hair, if the cortex is oval shaped you will have curly or wavy hair.

The physical thickness and length of hair depends on what type of hair it is. Vellus hair is the fine fuzz type of hair that's often called peach fuzz. Its very fine and colorless and often almost invisible to the naked eye.

Hair that is dark and very visible is known as Terminal hair. Terminal hair is the hair that we refer to when talk about hair. Whether a hair is a fine vellus hair or a thick dark hair depends entirely on the follicle that is producing the hair. In balding men thick terminal hair is often replaced by fine vellus hair. This is a result of the hair producing equipment, the follicle, suffering physical damage and being unable to produce terminal hair.

The average Caucasian person has 5 million hairs of which 100,000 - 150,000 are on the head. Blondes not only have more fun, they also have more hair, about 140,000 more than average, Brunettes have slightly higher than average hair about 105,000 hairs, and redheads have a little less than average about 90,000 hairs.

Hair grows in a cycle that consists of three phases: Anagen, Catagen and Telogen

Anagen - This is the growth phase that lasts between two and eight years. During the anagen phase the growth cells in the papilla rapidly divide and produce the hair shaft which becomes keratinized as it pushes up and out of the follicle into the pore. At the same time, the follicle grows down into the deeper levels of the dermis (skin) to get nourishment. People who have long anagen growth rates are able to grow very long hair and others have short growth phases and cannot grow very long hair. Hair grows at a rate of about a ½ inch per month, so a hair left uncut will grow to a length of between 12 inches and 48 inches.

Catagen - The Anagen phase is followed by a brief two to four week Catagen phase or transitional phase. This is part of a renewal process where the follicle is literally degraded and the hair stops growing but does not fall out. During the Catagen phase the hair follicle shrinks to about 1/6 of the normal length. The lower part is destroyed, the dermal papilla breaks away, the bulb detaches from the blood supply and the hair shaft eventually is pushed up as the follicle disintegrates.

Telogen - The follicle then goes into the Telogen or resting phase for two to four months, during this time the hair still does not grow but remains attached to the follicle while the dermal papilla is in a resting phase below. Approximately 10-15 percent of all hairs are in this phase at any one time.

After the Telogen phase the cycle is complete and the hair goes back into the Anagen phase. It is at this time when the new hair shaft is forming that the old hair is pushed out and lost.

On average 50-100 hairs are lost due to this natural growth process every day. This is normal hair loss and accounts for the hair loss seen every day in the shower and with hair combing. In healthy follicles these hairs will soon be replaced by new hair.

A variety of factors can alter the normal hair growth cycle and cause temporary or permanent hair loss including medication, radiation, chemotherapy, exposure to chemicals, hormonal and nutritional factors, thyroid disease, generalized or local skin disease, and stress.

WHAT CAUSES HAIR LOSS?
 

It is normal to lose between 50-100 hairs a day, this is part of the hair renewal process. However most people suffer from excessive hair loss at one time in their life. There are many reasons for this including medication, radiation, chemotherapy, exposure to chemicals, hormonal and nutritional factors, thyroid disease, generalized or local skin disease, and stress.

Many of these causes are temporary and a few are permanent. These are some of the more common reason for hair loss.

HORMONAL

Since hormones both stimulate hair growth and cause hair loss, hormonal changes by far have the biggest impact on hair loss. These can affect both men and women in the following ways:

This is the most common cause of thinning and affects both men and women. Men generally have hair loss concentrated in a specific pattern from the front through to the crown. Women tend to have thinning throughout their head without being in any specific pattern. This type of hair loss is caused by the androgen DHT, or Dihydrotestosterone. Since everyone has DHT that is produced by their bodies and only some people suffer from hair loss there has to be another factor involved. This other factor is having follicles that have a greater number of Androgen receptors for the DHT to attach to. This is the component that is inherited through the genes. To date the most effective preventative treatments are anti androgens, drugs that prevent the creation of DHT. In the future gene therapy will one day be able to alter the genes to prevent the follicles from being affected by DHT.
 

Childbirth
After pregnancy many women experience a loss of hair, this is caused many hair simultaneously entering the resting (telogen) phase. Within two to three months after giving birth, some women will notice large amounts of hair coming out in their brushes and combs. This can last one to six months, but resolves completely in most cases. This condition is caused by the hormonal changes that take place after a woman's body recovers from her pregnancy.
 

Birth control pills
Women who have a genetic predisposition to suffer from Androgenic Alopecia can have it occur at a much younger age by taking birth control pills. The hormonal changes that occur trigger the onset of the Androgenic Alopecia. If a woman has a history of female pattern loss in her family she should advise her doctor before going on the pill. After the discontinuation of the pill the woman may notice that her hair begins shedding two or three months later. This may continue for six months when it usually stops. In some cases the process cannot be reversed and the woman may not regrow some of the hair that was lost.

DISEASE OR ILLNESS
 

Since the follicle is a very sensitive it does respond to imbalances in the body. Most hair loss causes by disease or illness is temporary and resolves itself after the body has returned to a healthy condition.

High fever, severe infection, severe flu
Sometimes one to three months after a high fever, severe infection or flu, a person may experience hair loss, this is usually temporary and corrects itself.

Thyroid disease.
Both an overactive thyroid and an underactive thyroid can cause hair loss. Thyroid disease can be diagnosed by your physician with laboratory tests. Hair loss associated with thyroid disease can be reversed with proper treatment.

Deficient diet
Some people who go on low protein diets, or have severely abnormal eating habits, may develop protein malnutrition. To help save protein the body shifts growing hair into the resting phase. If this happens massive amounts of hair shedding can occur two to three months later. A sign of this is if the hair can be pulled out by the roots fairly easily. This condition can be reversed and prevented by eating the proper amount of protein. Its very important when dieting to maintain an adequate protein intake.

Medications
Some prescription drugs may cause temporary hair shedding in a small percentage of people. Examples of such drugs include some of the medicines used for the following: gout, arthritis, depression, heart problems, high blood pressure, or blood thinner. High doses of vitamin A may also cause hair shedding.

Cancer treatments.
Chemotherapy and radiation treatment will cause hair loss because it stops hair cells from dividing. Hairs become thin and break off as they exit the scalp. This occurs one to three weeks after the treatment. Patients can lose up to 90 percent of their scalp hair. The hair will regrow after treatment ends and patients may want to get wigs before treatment. There are some drugs in development to help prevent this hair loss from occurring.

Low serum iron
Iron deficiency occasionally produces hair loss. Some people don't have enough iron in their diets or may not fully absorb iron in their diets. Women who have heavy menstrual periods may develop iron deficiency. Low iron can be detected by laboratory tests and can be corrected by taking iron pills.

Major surgery/chronic illness
Anyone who has a major operation - a tremendous shock to the system - may notice increased hair shedding within one to three months afterwards. The condition reverses itself within a few months but people who have a severe chronic illness may shed hair indefinitely. A relatively unknown fact is that hair transplantation surgery can actually cause additional hair loss or "shock fallout". Hairs lost from shock fallout usually don't regrow.

Alopecia Areata
This type of hair loss is believed to be caused by the immune system reacting to hair follicles as if they were antibodies and shutting them down. The hair loss is usually limited to a coin sized area and all the hair in the area is lost leaving a totally smooth round patch. In a more severe rarer condition called Alopecia Totalis, all hair on the entire body is lost, including the eyelashes. Treatments include topical medications, a special kind of light treatment, or in some cases drugs.

Fungus Infection (Ringworm) of the scalp
Caused by a fungus infection, ringworm (which has nothing to do with worms) begins with small patches of scaling that can spread and result in broken hair, redness, swelling, and even oozing. This contagious disease is most common in children and oral medication will cure it.

Stress
Stress can cause hair loss is some people. Usually it occurs 3 months after the stressful event has occured and it may take 3 months after the stress period has ended for the hair growth to resume. In most cases it is temporary if the person is not predisposed to genetic or Androgenic Alopecia, if they are stress may trigger the onset of genetic hair loss or may worsen existing Androgenic hair loss.

MECHANICAL DAMAGE

Damage to the hair can be self inflicted either by intentional or unintentional means. Some people going through stress continuously pull at their hair until it comes out. Styling hair by bleaching, braiding and straightening can also cause damage and results in hair being lost.

Trichotillomania or Hair Pulling
Some children and less often adults play with their hair by pulling on it or twisting it. This can be part of a behavioral problem or a bad habit that is often done unconsciously. If the behavior is not stopped permanent hair loss can result from the constant stress on the hair. Its best to seek the help of a mental health professional to solve this problem.

Hair Styling Treatments
Many people change the appearance of their hair by using chemical treatments like dyes, tints, bleaches, straighteners, relaxers and permanent waves. If correctly done and done using reputable products, its rare to have any damage. However, hair can become weak and break if any of these chemicals are used too often. Hair can also break if the solution is left on too long, if two procedures are done on the same day, or if bleach is applied to previously bleached hair. Some chemical relaxers do contain powerful chemicals and there have been instances of people get chemical burns from these products resulting in permanent hair loss. Only go to qualified hair stylists and if doing it yourself make sure you only use reputable products and follow the product directions.

Hair Braids/Weaves
Many black women and some black men braid their hair or wear hair weaves. Under normal conditions these cause no problems. However if the weave is attached too tight or the braids are wrapped too tight, they put a constant strain on the hair follicle. If this is done for an extended period of time permanent hair loss can result. This is known as Traction Alopecia and is fairly common among people who braid or weave their hair. Make sure the person applying the braids or weave is qualified to do so and don't wear braids or weaves continuously for extended periods of time.