Eyelash loss can be attributed to a number of factors, including stress, endocrine disorders, side effects from birth control or other medication or direct trauma. To maintain full lashes, it is important to remove makeup at night, especially if wearing mascara.
Stressful conditions that may affect the hair growth cycle, which regulates hair growth on the head as well as eyebrows and eyelashes, include an extremely low-calorie diet, excessive weight loss, low levels of estrogen following childbirth or changes in oral contraception regimens, fever, major surgery or infections. The visible effects of stress on the hair growth cycle tend to follow a few months after the stressful event.
The hair growth cycle is regulated by the thyroid gland, so endocrine disorders such as hypothyroidism or hyperthyroidism can cause hair loss as well. An overactive gland, as seen in hyperthyroidism, causes hair to become thin; meanwhile, hypothyroidism causes hair to fall out.
In addition to medical reasons, eyelashes can fall out from trauma caused by simply rubbing the eyes too hard or using fake eyelashes or eyelash curlers incorrectly or too often. It is also important to remove mascara at night and brush the lashes with a clean wand to keep them healthy.