The idea that tears, especially those shed from crying, can stimulate the growth of eyelashes is a popular belief, but it is not supported by biological evidence. The notion likely stems from the observation of liquid touching the lash line. Tears do not contain the specific biological signaling molecules, like specialized peptides or prostaglandin analogs, necessary to extend the active growth phase of the hair follicle. Understanding the composition of tear film and the biology of the hair cycle reveals why this common assumption is a myth.
The Scientific Reality of Tears and Hair Growth
Tears lack the specialized biochemical messengers required to influence the hair follicle’s growth cycle. For an eyelash to grow longer, a substance must interact with the follicle at the cellular level and prompt it to remain in the active growth phase for a longer period. The chemical components in tears are not designed for this function and do not possess the necessary structure to bind to the receptors that regulate growth.
The primary role of the liquid secreted by the lacrimal glands is to maintain ocular health, not to stimulate hair proliferation. Introducing any liquid, including tears, simply washes over the surface. This action does not penetrate the dermal papilla, the structure deep within the skin responsible for hair growth signaling. Therefore, the simple act of crying has no effect on the length or density of your lashes.
What Tears Are Actually Made Of
Human tears are a complex three-layered fluid called the tear film, primarily composed of water. The aqueous layer, which makes up the bulk of the tear, contains electrolytes such as sodium, potassium, and chloride, which give tears their salty taste. This layer also holds protective proteins, including lysozyme, lactoferrin, and immunoglobulins, which function as antimicrobial agents to guard against eye infections.
The outer lipid layer is an oily mixture that prevents the watery layer from evaporating too quickly. An innermost mucin layer helps the tears spread evenly across the eye’s surface. While tears do contain a growth factor called Epidermal Growth Factor (EGF), this compound’s function is specific to stimulating the growth and repair of the cornea and other ocular tissues, not to initiate or prolong the hair growth cycle.
The Biology of Eyelash Growth
Eyelash growth is governed by the hair cycle, a highly regulated process that occurs in three distinct phases. The overall length of the entire cycle is significantly shorter for eyelashes than for the hair on the scalp. This short cycle is a biological mechanism that prevents the lashes from growing excessively long.
The first is the anagen, or growth phase, which is remarkably short for eyelashes, typically lasting only about 30 to 45 days. This brief period is the primary factor determining the maximum natural length of a person’s lashes.
Following the anagen phase is the catagen, or transition phase, where the hair follicle shrinks and growth ceases, lasting approximately two to three weeks. Finally, the lash enters the telogen, or resting phase, which can last for 100 days or more before the old lash sheds to make way for a new one. Because each eyelash operates on its own independent cycle, they do not all fall out at once.
Real Factors That Influence Eyelash Length and Density
The most significant determinant of eyelash length and density is an individual’s genetic code. Genes dictate the duration of the anagen phase, which is the single most important factor controlling how long the lashes grow. Some people naturally inherit a longer anagen phase, resulting in longer lashes.
Hormonal balance plays a considerable role in lash health; conditions like thyroid dysfunction can lead to thinning or loss of eyelashes. Nutritional deficiencies, particularly a lack of biotin, iron, or zinc, can impair the follicle’s ability to produce robust hair.
Maintaining the health of existing lashes involves gentle cosmetic practices, such as careful removal of eye makeup to avoid mechanical damage to the delicate follicles. Medical treatments, such as prescription topical solutions containing prostaglandin analogs, are the only clinically proven method to extend the anagen phase and genuinely increase lash length and density.