Phases of hair growth on the human body. Life cycle of hair growth and hair loss The dormant period of the hair follicle is called

Hair for many people is an important element that affects the correct perception of one's own personality, well-being and self-esteem.

For some, their loss is the cause of depression due to disturbances in relationships between people and problems with accepting their own appearance. In most cases, baldness affects older people, but sometimes it happens that young people are also affected by this disease.

Anagenic alopecia is an example of hair loss occurring in young people.

Hair growth phases

The density, thickness and amount of hair is an individual feature of each person, which is subject to significant fluctuations and depends on many factors:

  • hair colors;
  • gender;
  • race;
  • age;
  • genetic factors and environment.

Hair growth is asynchronous, which prevents the simultaneous loss of all hairs.

The hair growth cycle is divided into several phases:

  • Anagen- in this stage, the most intensive hair growth occurs. The hair roots in this phase are long, covered with an inner and outer sheath and are fully colored. This period lasts about 4-6 years. The amount of hair at this stage is 80-90%.
  • Catagen- transitional period. Hair color fades due to increased production of keratin. This phase lasts approximately 2-4 weeks, and amount of hair located in it is 2-3%.
  • Telogen- resting phase. The follicles in this phase are short, not covered with membranes and lose their color. This period lasts 2-4 months.

What is baldness

Baldness occurs when daytime hair loss is more than 100 and persists for several weeks. Hair can fall out on the entire surface of the head or only from limited places, sometimes it also affects other parts of the body (for example, armpits, eyebrows, eyelashes, beards in men).

Anagenic hair loss does not usually cause permanent baldness, and the hair grows back on its own after the cessation of action harmful factor. However, there are medications that can be helpful in treating baldness by speeding up hair regrowth. For example, minoxidil.

Distribution of hair on the body of men and women

Man with pronounced body hair

Hair removal, also known as "epilation" or "depilation" is the removal of body hair. The term is applied to the methods of achieving a given result.

Many products on the market turn out to be fake, exaggerating results or ease of use.

Kinds:

  • depilation- hair removal above the skin surface. The most common type of depilation is shaving or cutting. Another option is to use chemical depilators, which work by breaking the disulfide bonds that connect the protein chains that give hair its strength.
  • epilation- this is the removal of the entire hair, including the part that is under the skin.

Hair growth phases

The process of hair growth is cyclical and continues throughout our lives. Hair grows continuously. It has been established that during the day they grow faster than at night, and in summer and winter their growth slows down. The average hair growth rate in children is 13 mm per month, in adults 15 mm and in the elderly 11 mm.

The full development cycle of a fully formed hair consists of three phases: anagen, catagen and telogen.

Anagen- phase of active growth. The duration of this phase is genetically determined and lasts from two to five years. The cells of the hair follicle are intensively dividing.

Catagen- the intermediate phase lasts several weeks. Hair growth in the follicle stops, the pigment is no longer formed, the follicle shrinks, and its base moves towards the skin surface.

Telogen- rest or dropout phase. In this phase, the hair may spontaneously fall out or be removed with a slight effort. The duration of the phase is on average 3 months. The hair falls out at the moment when a new hair begins to grow under it.

According to studies, it is best to remove hair by depilation in the middle of the menstrual cycle in women, when hair growth is 2 times slower.

Hair removal methods

Temporary hair removal at skin level (depilation) lasts from several hours to several days and can be achieved with:

  • Shaving (manually or with an electric razor);
  • Depilators (creams or "shaving powders" that chemically dissolve hair)
  • Friction (rough surfaces are used).

Epilation, or hair removal from the roots, lasts from several days to several weeks, and can be done by:

Permanent hair removal (electrolysis)

For over 130 years, electrolysis has been popular in the United States. It is FDA approved. This method permanently destroys the germ cells responsible for hair growth by inserting a thin probe into the hair follicle and applying a current tailored to each type of hair and treating the area. Electrolysis is recognized by the FDA as the only permanent way to remove hair.

Permanent hair reduction (laser and other types of light hair removal)

  • (laser diodes and lasers);
  • (high energy lamps or IPL) or more commonly the method is called ;
  • (IPL/any laser)
  • Diode hair removal (high energy LEDs, but not laser diodes)

Experimental or ineffective methods

Methods with unproven effectiveness

Many methods have been proposed or sold without published clinical evidence.

  • Electric tweezers
  • Transdermal electrolysis
  • Percutaneous hair removal
  • Photoepilation
  • Microwave hair removal;
  • Nutritional supplements;
  • Topical over-the-counter drugs (also called "hair retarders", "hair inhibitors", or "hair growth inhibitors").

Efficiency comparison

In 2006, a review article was published in the journal Lasers in Medical Science, where researchers compared intense pulsed light (IPL), alexandrite, and diode lasers. The review found no statistical difference in efficacy, but a higher frequency side effects with a diode laser. Hair reduction after 6 months was 68.75 for alexandrite laser, 71.71 for diode lasers, and 66.96 for IPL. Side effects were reported at 9.5 for the alexandrite laser, 28.9 for the diode, and 15.3 for the IPL. All side effects were temporary, even skin pigmentation was eliminated within 6 months.

Advantages and disadvantages

There are several drawbacks to many of the aforementioned hair removal methods. The main ones are: skin inflammations, burns, rashes, scars, ingrown hairs, and infected hair follicles. One issue that can be considered both a disadvantage and an advantage, depending on the individual's point of view, is that hair removal has the effect of removing information about a person's hair growth type due to genetic predisposition, disease, androgen levels (e.g. due to for hormonal imbalances during puberty or side effects of medications), and/or gender status.

Another disadvantage of permanent (laser, electrolysis) hair removal is the reduction in the ability of human skin to regenerate, since the hair follicles contain stem cells that help with healing.

Cultural and gender aspects

The hairline is usually present on the entire human body, during puberty the hair thickens and changes color to a darker one. As a rule, men have more visible body hair than women. Both men and women have visible hair on the head, eyebrows, eyelashes, armpits, pubic region, arms and legs, men also have thicker hair on the face, abdomen, back and chest. Hair usually does not grow on the lips, the inside of the arm or leg, or on certain parts of the genitals.

Each culture of human society has its own social norms regarding the presence or absence of body hair, which have changed from one generation to another.

The practice of hair removal in almost all cultures dates back to Paleolithic times. Removal methods and locations have varied over time and culture, yet shaving remains the most popular method. Different standards have taken place in both women's and men's fashion. People who did not adhere to the aesthetic norms of society faced real or imaginary problems in society. In the Middle East, the removal of hair from the female body has been considered proper hygiene, due to local customs, for many centuries.

With the increasing popularity of revealing clothing (swimsuits, tops, shorts, etc.), body hair removal (legs, armpits, etc.) has also increased in popularity. In the US, the vast majority of women regularly shave their legs and underarms, while about half also shave their bikini line.

Most people delete pubic hair for aesthetic or sexual reasons. However, some Western women fundamentally do not shave their hair from open places in order to protest the imposed patterns and aesthetic rules on society.

Men are forced to shave their faces every day also for the purposes of aesthetic norms and rules. However, some men shave their beards because their beard color is different from their head hair color, or because their facial hair grows in different directions, in such cases it is difficult to look well-groomed.

Elizaveta Krasnova

Stylist-image maker

Articles written

Throughout our lives, hair grows. This process is natural and is an integral part of the functioning of a healthy organism. Many mistakenly believe that strands grow continuously and only some of them fall out for some reason. However, this opinion is erroneous, since each hair passes through several stages or phases of development during its not very long life cycle.

The formation of our hair begins in the womb. At this stage, only vellus hair on the body of the head is laid and grows. They are distinguished by their softness and insignificant length, in addition, they lack pigment. Shortly before the baby is born, some of these hairs are replaced by pigmented ones.

In the first years of a baby's life, vellus hairs replace the so-called intermediate ones. Later, namely during puberty, they are transformed into stiffer strands, which are called terminal. They are much denser and may slightly differ in shade from the previous ones. At this stage, hairs on the body also appear. In the region of the eyebrows, eyelids and nostrils there is a special type - bristly hair. Each person on the surface of the head simultaneously has all the named species.

In general, strand growth is carried out due to cell division, which lie in the deep layers of the dermis and are not visible to our eyes. In order to understand this process, it is necessary to learn more about the structure of hairs.

Each hair consists of several parts:

  1. The rod is the part that is visible and lies above the surface of the epidermis, it is composed of inanimate cellular structures that are filled with keratin;
  2. Root - this constituent element lies at a depth of approximately 2.5 mm in the thickness of the skin, and it is composed of living cells that are able to develop, continuously divide and grow.

It is the bulbs that largely determine the state and appearance hair, and also determine the process of hair growth. However, the division of cellular structures cannot occur without the participation of tissues located near the roots. Together, these structures make up the part of the hair called the follicle or sac. Blood vessels and nerve endings approach it.

Interestingly, the shape of the follicle determines the appearance of the hair:

  • curly curls appear from the oval;
  • straight, smooth strands grow from a round hair follicle;
  • kidney-shaped gives curly hair.

The hair follicle is of great importance for the growth and health of curls. If it is damaged, then the root will die off, and in the future its restoration seems impossible. Also, the sebaceous glands pass next to the hair follicle, they also significantly affect the condition and beauty of the hair. With underdeveloped ducts, the skin of the scalp is dry, its peeling is observed. If the sebaceous glands are enlarged and actively working, then the dermis will be oily, shiny. The produced secret has an antibacterial and protective function for the skin.

Healthy, well-maintained hair follicles are able to ensure full and rapid hair growth, as well as increase their lifespan.

The growth process of strands is cyclical. During the period of its life, the hairs go through several successive stages, each of which has its own characteristics.

Anagen - growth stage

The whole process of strand growth begins precisely with the growth phase - anagen. At this moment, the hair cells that lie in the bulb begin to activate for division. The "signal" for this implementation of this process comes from the hormones contained in the blood. With the formation of new cellular structures, the follicle grows in width, a rod is formed and gradually thickens, and a coloring pigment, melanin, is formed. The pigment quickly penetrates the structure of the hair and causes its color. However, the rod does not yet cross the boundaries of the epidermis, but only approaches its upper layer.

This phase of hair growth is the longest, it can last from 2 to 5 years. True, as a person grows up and ages, the stage gradually becomes shorter and shorter. At this stage, there is usually about 80-90% of all curls.

During the anagen period, the hair gradually begins to go beyond the upper border of the epidermis and rises above the surface of the skin. The bulb by this time had already completely formed and acquired its outlines: in some people it is rounded, in others it is slightly flattened or has an elliptical shape. The hair shaft lengthens during the anagen phase by an average of 0.5 mm daily.

Catagen - intermediate stage

This is the shortest stage in the life cycle of strands, catagen takes only 2-4 weeks. By this point in time, the hair shaft completely comes to the surface and is significantly lengthened. The bulb in the sac rises slightly, moving closer to the boundaries of the epidermis, its cells begin to regress. In the catagen phase, the blood stops supplying the hair follicle, and it gradually shrinks, decreasing in size to 1/6 of its previous state. At the same moment, the production of the coloring pigment stops.

The cellular structures of hairs and roots that have lost their nutrition stop dividing further, and the growth of curls stops completely. About 2-3% of all strands are at the catagen stage.

The phases of hair growth, along with the peculiarities of their structure, determine the appearance of the entire head of hair. For example, to grow long and beautiful curls much easier at a young age, this is due to the fact that with each new cycle the hair grows to a shorter length. In addition, after 30 years, the rate of regrowth of the strand becomes gradually lower and lower. In total, each hair in a person goes through about 25 cycles.

Telogen - the resting stage

This is the last stage in the life cycle of curls. During the telogen phase, the hair follicle is at rest. During this period, the hair is held only by the skin, so it is not difficult to remove it, or it will fall out on its own. This usually happens at the moment when a new, born and emerging hair begins to push out the old one. At this time, the hair follicle again passes into the anagen stage, and the process of the birth of a new hair begins in it.

The duration of the telogen phase is 3 months. About 10% of all curls are at this stage at one time, so we can lose 50-100 hairs every day. Next, a new cycle of strand growth begins. Thus, on average, from 20 to 40 hairs are born in the follicle during the entire life of a person.

Our strands grow daily and continuously, during the day this process is faster than at night. During the off-season (autumn and spring), the speed also increases. In children, curls grow by about 13 mm per month, in adults a little faster - by 15 mm, this process is most active in the period of 16-25 years, it slows down with age, and the hair growth rate no longer exceeds 11 mm.

Loss and growth cycle of strands

Loss of curls is a completely normal and natural process, so old hairs are gradually replaced by new ones. At the same time, growth and rest phases are observed in neighboring follicles at different times, otherwise bald patches would periodically appear on the scalp.

For those people who are not familiar with the problem of severe hair loss, each newly growing hair does not differ from the previous one, it has the same thickness and can grow to the same length.

The rate of hair loss is up to 100 pcs. daily, this is about 1/10 of the hair. If this number is much larger, then there is cause for concern, perhaps in this case we are already talking about a pathological process - loss of curls.

In the early stages of baldness, weakening, thinning and deterioration of the strands are observed. If at this moment to resort to treatment, then there is every chance to restore the roots to their former health. Otherwise, the curls will become worse, thinner, and the rate of their growth will slow down, the hair will fall out more often, and bald areas will become noticeable on the head.

Causes of early baldness

  1. Incorrect and too frequent coloring causes the destruction of hair follicles, as chemical substances able to penetrate deep into the dermis. This situation leads to a premature transition of the hairs into the catagen phase.
  2. When there is a deficiency of vitamins and nutrients, the hair follicles gradually begin to die off, and the rods of the strand lose their radiance and elasticity.
  3. Diseases internal organs and the use of some medicines lead to a deterioration in the condition of the bulbs and strands.
  4. Stressful situations and excessive physical exercise lead to the fact that the hair begins to thin out not immediately, but after 2-3 months.
  5. Incorrect care of curls, the influence of direct rays of the sun on them, overheating and hypothermia have a detrimental effect on the condition of the hair and their bulbs.

Ways to combat baldness

The problem of hair thinning is observed in cases where the telogen stage in the life cycle of the strands begins to drag out and take longer, or the resting phase affects more than 10% of the scalp. In this case, it becomes noticeable how the density of the curls decreases, and the strands are lost more and more often.

  1. At the heart of most developments in the fight against baldness is the idea of ​​​​reducing the duration of the telogen and stimulating the “falling asleep” bulbs.
  2. Another group of methods is aimed at restoring the functions and activity of hair follicles.
  3. The effectiveness of cosmetic products containing vitamins and other nutrients for the restoration of hair follicles has also been proven.

Our curls grow constantly throughout our lives, but the speed is different. This indicator depends on age, season, environmental conditions and individual features each person.

The life cycle of hair is often compared with the process of plant growth during the year: roots appear and develop in spring, active growth begins in summer, by autumn it slows down, a period of regression begins, and death occurs. In this regard, you should not be afraid of the fact that strands leave our head every day, but with a strong loss, you need to think and take appropriate measures.

One of the most popular questions among clients who decide to conduct laser hair removal or photoepilation, is the question “Why is it necessary to carry out a set of procedures if this technique is one of the most effective?”

For a detailed consideration of this issue, it is necessary to delve a little into the theory of human physiology. A section is presented for your consideration, which gives an approximate explanation for the client, what phases of hair growth exist, how these cycles affect the effectiveness of the procedures and, and why, in the end, a course of procedures is required when using these techniques.

Human hair growth is divided into three phases:

  1. Anagen. This is the active stage of hair growth. The increase in hair length occurs due to the most productive cell division of the hair follicle; during this period, the pigment is actively produced, due to this, the hair clearly stands out against the background of the skin.

Removal of unwanted hair using photoepilation and laser hair removal is possible only at this stage, since there is a complex effect on both the pigment produced and the mass of follicle cells.

In this phase, a person can have from 40 to 80 percent of the total hair volume, so it is impossible to remove all unwanted hair in one procedure; it is necessary to wait until the maximum possible number of hairs is in the stage of active growth. Hair can be in this stage from 2 to 7 years.

  1. Catagen: phase of slowing hair growth. At this stage, the process of cell division slows down, the production of hair pigment stops. It is almost impossible to achieve hair removal at this stage. The duration of this stage can last several weeks.
  2. Telogen. Phase of hair loss. The hair follicle enters the resting phase, stopping almost all activity processes. Exposure of light fluxes to an inactive follicle is also impossible, so it must be expected to return to the active growth phase. This period can last up to 3 months.

As can be seen from the previous conclusions, for the qualitative removal of unwanted hair, it is necessary to process the maximum number of hair follicles, but this is possible only during the period of active growth. Considering that the course of procedures and on average is from 6 to 10 procedures, and the interval between them is 1 - 1.5 months, it can be assumed that it is in this time period (6 months - 1 year) that the maximum amount of hair will be affected. to stop their growth for a long period of time (3-5 years).

Here it is important to explain to the client that the effect of this procedure is long-term, but not lifelong, since the hair follicles tend to completely recover. Also, hormonal changes can affect the restoration of hair growth, so the client should always be prepared for the fact that health problems can affect the state of unwanted hair growth.


Many people think that hair grows continuously, and only a small part of it falls out, and then very rarely. In fact, hair growth can be divided into three stages. At the same time, each hair cycles through all phases of growth many times throughout a person's life.

Anagen

Anagen- the period of active hair growth. Lasts two to six years. With age, this phase is shortened and quickly replaced by the next. It is divided into six stages:

  1. Hair bulb cells increase in size, intensive RNA synthesis occurs;
  2. The hair bulb grows deep into the epidermis and surrounds the dermal papilla. Cell differentiation begins into different layers of the hair and the outer shell of the root in the matrix ring that surrounds the dermal papilla;
  3. Cell division continues. By this time, the hair follicle has reached its maximum length, which is three times longer than in the resting phase. The dermal papilla is now fully formed. Melanocytes (epidermal cells that are responsible for the production of melanin, which gives hair a certain color) are located along the cavity of the papilla, each of which (each of the melanocytes) forms melanin granules. The outer shell of the cavity of the follicle is now an elongated cone that expands from above;
  4. At this stage, melanocytes begin to produce the pigment melanin. Although the hair is already formed, it does not extend beyond the cone-shaped cavity, which continues to expand;
  5. The hair grows to the upper border of the epidermis, the bulb acquires a finished shape, which in some hairs is symmetrically rounded, in others it is squeezed like an ellipse;
  6. The last stage begins after the hair begins to rise above the skin and continues until the catagen phase. In mice in the sixth stage of anagen, hair grows at a rate of one mm per day. In humans, this stage lasts from two years. Hair grows at a rate of 0.5 mm per day.

Catagen

Catagen- the period of transition from active growth to rest. Atrophy of the hair papilla begins, as a result of which the cells of the hair bulb, deprived of nutrition, stop dividing and undergo keratinization. This stage lasts for several weeks, after which the resting stage (telogen) begins.

Telogen

Telogen- a period of rest or rest of the hair. Interestingly, the mechanical removal of hair in the telogen stage always entails the onset of the anagen stage, that is, the hair begins to grow again. All hair that remains on the brush or falls out during the day is telogen hair.

At healthy people 80-90% of hair is in the anagen stage, 1-2% is in the catagen stage, and 10-15% is in the telogen stage. Studies show that excessive hair loss corresponds to a change in the above ratio: a decrease in the percentage of hair in anagen and catagen, but an increase in the percentage of telogen hair. If you notice that the amount of hair falling out during the day has increased dramatically, then know that this is the first sign of a deterioration in the condition of your hair. In people who are not prone to baldness, each new hair does not differ in thickness, potential length and other characteristics from the previous ones; at the same time, in balding, each new generation of hair decreases in thickness, color (lightens), the growth rate and duration of the anagen phase decrease. Ultimately healthy hair gradually degrade to vellus and colorless hair.