Hair grows long because new hair cells continuously develop in the hair bulb. This process, known as the anagen phase, allows the hair shaft to elongate.
The Anagen Phase: The Growth Engine
The primary reason hair grows long is directly linked to the duration of its anagen phase. During this phase, cells in the hair bulb actively multiply, pushing the existing hair shaft outward and causing it to lengthen.
- Continuous Cell Growth: As long as new hair cells are generated in the hair bulb, the hair strand will continue to grow longer.
- Hair Cycle: Hair growth is cyclical, with phases of growth, rest, and shedding. However, the anagen phase is what dictates the potential length of an individual hair.
- Individual Variation: The length of the anagen phase varies among individuals. This is the reason why some people can grow extremely long hair, while others reach a certain length and hair growth stops.
Percentage in Anagen Phase
At any given time, the majority of your hair is in the anagen or growth phase. According to the provided reference:
At any point in time, about 90 percent of a person's total amount of hair is in this growth phase.
Therefore, most of your hair is always actively growing longer.
Understanding Hair Growth Phases
While the anagen phase is crucial for length, understanding other stages can help give a more complete picture:
- Anagen Phase (Growth Phase): As detailed above, this is when new cells actively form in the hair bulb, pushing the hair shaft out of the follicle and allowing it to grow in length.
- Catagen Phase (Transition Phase): This is a short phase where the hair follicle begins to shrink, and hair growth stops.
- Telogen Phase (Resting Phase): The hair follicle is dormant, and the hair does not grow. Eventually, the hair sheds, and the follicle returns to anagen.
Key Factors for Hair Growth
While the anagen phase is the driving factor for hair length, other factors include:
- Genetics: Genetics plays a significant role in determining the length of a person’s anagen phase and therefore how long their hair can potentially grow.
- Nutrition: A balanced diet supports healthy hair growth.
- Hormones: Hormones can also affect the hair cycle and growth.
In summary, the continuous growth of hair is primarily due to the anagen phase where new hair cells are produced, causing hair to grow longer. This process is also aided by a variety of factors such as genetics, nutrition and hormones.
