Apple #123: Nasal Hair

I'm wondering, why does your nasal hair get longer when you get older? Especially since, for many people, the hair on their head starts to disappear?

This person isn't old enough yet
to be experiencing lengthy nasal hair.

• The answer, in a word, is testosterone. This is a steroid hormone that controls the growth and maintenance of masculine characteristics, such as hair.

• Apparently testosterone dictates all sorts of stuff that happens to your hair throughout your life. When you hit puberty, it's testosterone that makes the hair start growing in your armpits and pubic area. When you hit a certain older age, your hair may stop growing in, or even falling out, and again, it's testosterone to blame. Nasal hairs, same thing. Testosterone.

• Specifically, testosterone gets converted to another substance that shrinks the size of hair follicles on your head. Because the follicles are getting smaller, the diameter of each hair gets thinner. Finally, the follicles close completely and no hair can grow out of them. That's basically what's happening when men start going bald or women start losing hair.
  

• Strangely, even though testosterone is what's behind hair loss, it's also the culprit in more hair growth in places like your nose and your ears and eyebrows. Why that same follicle-shrinking thing doesn't happen in these other locations but it does happen on your head is not something I could find an answer to.

• Many sources I've read on this subject say that long nasal hairs is something only men experience. But if I correctly remember the faces of some of my teachers, women get long nose hairs, too.

• As it turns out, for women, as they age, their bodies produce less estrogen, especially after menopause. Without the estrogen to "oppose" or block the testosterone, the testosterone goes to work on a woman's hair follicles and may make it stop growing on her head, or grow longer in her nose.

• So basically, if you've got testosterone, and apparently everybody does, your hair is going to start doing new things starting around age 30.
  

Sources
Vanderbilt Faculty & Staff Wellness Program, Men and Aging
SharpMan.com, Ear Hair: What Gives?
Pioneer Thinking, Female Hair Loss