Eyelash and Hair Growth
Eyelashes exist for protection. They activate the blink response so that dust, debris, dirt, and other foreign objects don't get lodged on our eyes. Although it may not seem like it, hair growth is a preset function of the body. Every hair on your body follows a specific growth cycle and will grow to a certain length, about 3/8 of an inch on average. Hair eventually falls out and a new hair grows in its place. The upper eyelid holds about 90 to 150 lashes, while the lower eyelid holds about 70 to 80 lashes. The hair growth cycle consists of three distinct stages.
Anagen (Growth) Phase
The anagen phase is also called the growth phase. This is the phase when lashes are actively growing, and it lasts between 30 and 45 days. Only about 40 percent of the upper lashes and 15 percent of the lower lashes are in the anagen phase at any given time. Each lash will grow to a specific length and then stop.
Catagen (Transition) Phase
The catagen phase is also referred as the transition phase. During this phase, the lash stops growing and the hair follicle shrinks. If an eyelash falls out or is plucked out during this phase, it won't grow back right away because the follicle needs to complete the catagen phase before it can move on to the next one. This phase typically lasts between two and three weeks.
Telogen (Resting) Phase
The telogen phase is also known to as the resting phase. This phase can last more than 100 days before the eyelash falls out and a new one begins to grow. Because each individual lash is in its own phase of the growing cycle, it's normal for a few lashes to fall out each day. It typically takes between four and eight weeks to fully replace an eyelash. Each hair follicle is independent and goes through the growth cycle at different times