Hair cycle: everything you need to know about the different phases of hair

In addition to their aesthetic role, hair has several functions: they play a thermoregulatory role by protecting the head from cold and heat, and help prevent shocks, etc.

“A hair is composed mainly of 90% protein (keratin and melanin) and 10% water, lipids, trace elements (iron, zinc, iodine, calcium, manganese)”, explains Fil Santé Jeunes (source 1).

• There keratin constitutes almost 80% of the hair fiber and provides impermeability and protection to the hair;
• There melanin plays a major role in hair pigmentation, but also in their depigmentation over the years.

The hair is divided into two parts:

• The root (the hair bulb), where the cells multiply: “pushed upwards, these cells are loaded with keratin, to form the hair shaft”, describes Fil Santé Jeunes;
• The stem (the hair shaft) itself made up of three concentric layers of cells: the bone marrowin the center, the cortex, composed of cells rich in keratin and pigments which determine the color, vigor, elasticity, regrowth or even the direction of the hair, and the cuticle, an outer layer with an essential role that protects the hair and allows it to be healthy.

The hair cycle is divided into 3 phases.

The growth phase of hair is called the anagen phase. This is where the concentration of melanin is highest. The anagen phase can last more or less long depending on the person, but it lasts on average 5 years in women and 3 years in men.

There catagen phase is the shortest of the cycle; it is a transitional phase that marks the end of active hair growth. The hair follicles, which are located in the dermis and can be compared to a bag containing the hair, retract – the cells stop multiplying, so hair growth is very slowed down, or even stopped. The catagen phase can last more or less long depending on the person, but it lasts on average two to three weeks.

There telogen phase corresponds to the resting phase, during which the inactive hair no longer grows but remains anchored to its hair follicle for two to three months, before falling out naturally. This is what allows the new hair to grow on top. It is important to know that we lose on average 60 hairs per day in autumn, 45 in spring, 20 to 25 in winter and summer.

As the years go by, our bodies change. And so does our hair. Many women notice differences in texture, color or thickness hair as we age. But hair loss remains the most alarming change.

As a reminder, it is completely normal to losing a hundred hairs a daybut when the growth period becomes too short and the hair falls out too quickly, you may start to notice more significant shedding. If you notice that your hair is no longer able to grow past your shoulders, this is a sign that hair follicles no longer function as well as before.

These changes may be linked to genetic factors, but also to the foodhas healthy lifestyleAt stressto a possible diseaseand the way in which we takes care of hair. Hormonal changes also play a very important role in hair development. Here's what you can expect in hair growth, depending on your age.

Hair is usually at the top of their game. The stems are thick and the cuticles are tight. The only changes that may appear are associated with the stressto a drastic dietor to means of contraception.

If we have a child, there pregnancychildbirth and breastfeeding impact our hormones and hair cycle, leading to hair loss and thinning.

Pregnancy simulates the sebaceous glands which lubricate and moisturize hairResult: shiny hair.

But after giving birth, the drop in hormones can make the dull hair and brittle.

When there is stress in professional and personal life, hair becomes brittle. Around the age of forty, when the first white hairs begin to appear, many women choose to dye their hairwhich can damage and weaken them any further.

At the age of menopause, hormonal fluctuations will result in a shorter hair cycle. Some women have gray or white hair at this stage, and the lack of melanocytes is linked to more brittle hair.

Once menopause occurs, the drop in estrogen and increase in testosterone affects women's (and men's) hair follicles. Hair is even more brittlewhich is why many women opt for short haircuts.