Your hair has a growth cycle that consists of three parts: regeneration, degeneration and rest cycle . But sometimes, this cycle can be interrupted, causing hair to stop growing. Many factors can contribute to stopping hair growth in humans, however, most are not of medical concern.
How long does it take to grow hair?
Science assures us that it grows about 0.4 millimeters a day, 1 centimeter a month and about 15 centimeters a year . In addition, it tends to grow faster in women than in men, and with aging the rate of growth slows.
The growth is not homogeneous. If you cut your hair straight, you will know that there are areas that always grow faster than others, and there will always be a percentage of hair in each of the phases of the cycle.
On the scalp and, in the absence of any problem, there are 85 percent of hairs in anagen phase, 14 percent in catagen and 1 percent in catagen. This means that hair grows faster on the crown than in other areas.
Factors that influence hair growth
Hormones
Your hormones can promote hair growth or loss. They also help regulate the hair growth cycle and the time each stage takes to complete. The hair growth phase of the scalp, known as anagen , usually lasts between two and three years.
However, hormonal irregularities can make this phase last longer in some people, which can lead to less hair growth overall.
Autoimmune disease
A medical condition known as alopecia areata can also cause your hair to stop growing. This condition can also lead to hair loss from the scalp. Although the cause of this disease is unknown, scientists believe that some people are genetically predisposed to developing alopecia areata.
A family history of the disease can also put you at higher risk for the disorder. You will lose hair if you suffer from alopecia areata; however, most people tend to regain hair growth after several years.
Stress
High levels of stress can also cause hair growth to stop. Physical and emotional stress can also lead to hair loss. The medical condition of telogen effluvium can develop as a result of severe mental stress, such as the loss of a loved one.
This physical and mental stress can disrupt your hair's normal growth cycle , which normally grows in cycles of 2 to 5 years. Hormonal imbalances, viruses, or physical trauma can also trigger this condition. Telogen effluvium usually resolves on its own and does not require any treatment.
