Anagen, catagen and telogen are terms that signify the stages of the hair growth cycle. Anagen is the period when hair continues to develop and appears well-nourished. Right after this phase, there's a short phase called catagen, which is a degradation period, during which the hair follicle is cut of from the blood supply. Throughout this phase, the hair follicle starts shrinking as well as the hair shaft is starting to be pushed upwards.