Why do eyelashes not grow?

Answered by James Kissner

Eyelashes, those tiny hairs that frame our eyes and enhance our beauty, are a fascinating feature of the human body. Many of us may have wondered why they don’t grow as long as the hair on our heads. The answer lies in the natural hair growth cycle and the duration of the growth phase, known as the anagen phase.

To understand why eyelashes don’t grow as long as head hair, let’s first delve into the hair growth cycle. Hair follicles, the tiny structures in our skin from which hair grows, go through three phases: anagen, catagen, and telogen. The anagen phase is the active growth phase, during which cells in the hair follicles rapidly divide and produce new hair. The catagen phase is a transitional phase, where hair growth slows down, and the hair follicle shrinks. Finally, the telogen phase is the resting phase, when the hair follicle is dormant before shedding the old hair and starting the cycle anew.

The duration of the anagen phase varies for different types of hair. Head hair, for instance, can spend up to 7 years in the anagen phase, allowing it to grow significantly longer than eyelashes. On the other hand, eyebrows and eyelashes have a much shorter anagen phase, typically lasting only about 30 days. This limited duration restricts the length to which they can grow.

The reason for the shorter anagen phase of eyebrows and eyelashes is not entirely clear. One theory suggests that it may be related to the size and location of the hair follicles. Eyebrow and eyelash follicles are smaller and shallower compared to scalp follicles. Additionally, they are located in areas with more delicate skin, where longer and heavier hairs could potentially cause discomfort or interfere with vision.

In my personal experience, I have noticed that when I accidentally pluck an eyelash or tweeze an eyebrow hair, it tends to grow back relatively quickly. This rapid regrowth can be attributed to the short anagen phase, which allows for a faster turnover of hair follicles. It’s quite fascinating how our body’s natural mechanisms work to maintain the balance and functionality of our hair.

To summarize, the reason why eyelashes don’t grow as long as head hair is primarily due to the shorter duration of the anagen phase. While head hair can spend several years in the active growth phase, eyebrows and eyelashes only have about a month before entering the next phase of the hair growth cycle. This limited growth period, combined with the size and location of the hair follicles, prevents them from growing as long as head hair.