The Hair Cycle is a naturally-occurring phenomenon. It's a term used to describe the cyclical degeneration (and regeneration) of every hair follicle on our head. Here’s how the hair cycle works: for 2-6 years, a hair follicle will grow thick, healthy hair. Then, for reasons not fully understood, a hair will detach itself from its hair follicle, shed (fall out), and then the hair follicle will degenerate. Then, in a few months, a new hair follicle will emerge, replace the degenerated hair follicle above it, start growing a new hair – and a new hair cycle begins. This several-year cycle repeats indefinitely, everywhere we have hair, and for almost every hair-bearing species on the planet.
In a normal scalp, about 15% of our hairs have already detached from their hair follicle and are ready to shed. This is why, even in the absence of hair loss, it’s normal to shed 150+ hairs per day. It’s just a part of the natural hair cycle! And once those follicles regenerate, the hair should always come back... because the hair cycle repeats indefinitely.
Knowing this, there tend to be two main ways we can lose hair.
- The health of our hair follicles can become compromised — thus, leading them to produce thinner, wispier hairs. (Hair Follicle Miniaturization)
- Our hair cycle can stop working: for instance, if a healthy hair sheds, but a new hair follicle never regenerates to regrow that lost hair. (Hair Shedding Disorders)