The idea that hair changes every seven years is a myth. While hair does grow and shed continuously, the process is gradual, and there's no definitive time frame for a complete hair cycle.
Here's what's true about hair growth:
* Growth phases: Hair goes through phases of growth, rest, and shedding.
* Cycle length: Each hair follicle has its own cycle length, ranging from 2 to 7 years.
* Continuous process: New hair grows while old hair sheds, making it appear as though hair changes over time.
So, your hair isn't replaced all at once every seven years!