The normal hair follicle is more complex than most people realize. From each hair follicle, multiple hairs sprout. There is a primary hair that goes down all the way to the main root and smaller secondary hairs that come out in the same place but don’t go all the way to the root. The primary hair is “grasped” by a tiny muscle called the erector pili muscle and, as you might have guessed, it is the muscle that makes your hairs “stand on end,” or erect, under different circumstances. Remember that muscle for later. It is important.
As you can see in the drawings, all the smaller hairs, or secondary hairs, are lost before that primary hair gives out (Phases 1–7). That is why so many people will experience thinning hair long before they start to see any true baldness. That is why going bald can sneak up on you.
It may turn out that it is the loss of that arrector pili muscle (when the last hair is lost) that determines whether hair loss is permanent (or nearly so) or can return to normal function. Where the arrector pili muscle “grasps” the primary hair is known as a stem cell niche (a tight little corner where the all-important stem cell can hide), and when that muscle completely separates from the hair and is replaced by fat, hair loss can only be partially restored—at best.
What this means is that the best time to start to deal with hair loss is before the thinning has progressed too far and before baldness has existed for too many years. To preserve hair, the attempt is best made when the arrector pili muscle is still attached to that last standing, primary hair.