Just like other hair on your body, lashes have a growth cycle in which they grow, hang on for a while, and then naturally shed off. The eyelash growth cycle consists of three phases: the anagen phase, the catagen phase, and the telogen phase. lash serum actually works by extending the telogen phase of the lash growth cycle. This helps the lash to hold on for a longer period of time. Since your lashes won’t be falling out as frequently with the help of lash serum, they will appear to look fuller and denser.