Clinical studies have demonstrated that a woman’s average lash length, thickness and color start to decrease between her 20’s and 30’s. By the time she is 60, her lashes will be considerably thinner, shorter and lighter in color. Because just like other human body hair, there is some natural shedding of eyelashes as new growth pushes out old eyelashes and replaces the hair which grows along the eyelids. This is a perfectly natural body function. However, there are other reasons why your eyelashes thin or for eyelash loss, such as: age, normal cycle, care or trauma, medical condition, drug interaction.