In a perfect world, hair follicles would follow the growth cycle exactly as planned. At any moment, over 90% of your hair follicles would be enjoying more than two years in their growth phase before gracefully transitioning to a few months of resting. And then finally, five to 10 percent of your hair would gently shed away, making room for more growth and leaving you with tons of thick, healthy hair.
But thanks to the sensitivity of our hair follicles, a number of influences can to put so much stress on the hair growth cycle that the whole business is derailed, leaving you with sudden, noticeable hair changes like thinning and loss.