Here's a more detailed breakdown:
* Anagen (Growth Phase): This is the active growth phase and can last for several years. Most of the hairs on your head are in this phase at any given time.
* Catagen (Transition Phase): This is a short transition phase, lasting about 2-3 weeks, where hair growth slows and the hair follicle shrinks.
* Telogen (Resting Phase): This is the resting phase, lasting around 3 months, where the hair doesn't grow and is eventually shed.
Once the telogen phase is complete, the hair is naturally shed, and a new hair starts to grow from the same follicle, beginning the cycle again. So, while an individual hair strand can last for several years, it will eventually be shed as part of this natural cycle.
Factors that can affect the hair growth cycle and how long a strand of hair stays on your head include:
* Genetics: Determines hair growth rate and cycle length.
* Age: Hair growth tends to slow down with age.
* Nutrition: A balanced diet is important for healthy hair growth.
* Hormones: Hormonal changes (e.g., pregnancy, menopause) can affect hair growth.
* Health conditions: Certain medical conditions and medications can impact hair growth.
* Hair care practices: Over-styling, harsh treatments, and poor hair care can damage hair and potentially shorten its lifespan.
In summary, while individual hair strands can last for 2 to 7 years on average, they are constantly being replaced through the natural hair growth cycle.