A large amount of stress can cause hair loss. Every person looses 81 - 100 strands of hair per day. The most common type of hair loss is the kind that we inherit, andreogenetic alopecia, genetic hair loss. But in some cases, other factors  like severe stress can cause hair to become unhealthy and suddenly begin to fall out. If you are taking a hair vitamin supplement, and stop taking it, your hair will revert back to it's natural state. Just as when you decide to leave the world of the hair relaxer. As the new  hair grows, there is a line of demarcation, this line separates the old hair from the new. Which in cases of severe stress can cause the hair to break off at that line due the two different hair textures.