The hair growth cycle consists of three main phases: anagen (growth phase), catagen (transitional phase), and telogen (resting phase). Laser hair removal is most effective during the anagen phase when the hair is actively growing and has the highest concentration of melanin, the pigment targeted by the laser. Treating during this phase ensures the laser energy is absorbed by the hair follicle, damaging it and inhibiting future hair growth. Since not all hairs are in the anagen phase simultaneously, multiple laser sessions spaced several weeks apart are needed to target hairs in different stages of the growth cycle for optimal results.