When our hair is actively growing, it’s in what’s known as the anagen phase (via BBC Science Focus). That growth then comes to a stop in the catagen phase, and the hair remains at rest in what’s called the telogen phase until the cycle begins all over again. Testosterone is a major contributing factor in the growth of terminal hairs, such as those inside our nose (per Nebraska Medicine). As we grow older, the accumulation of testosterone in the body can prolong the amount of time our hair stays in the growth phase, explains The New York Times. This process is called anagen sensitivity, reports the Cleveland Clinic. That’s what makes those scraggly nose hairs grow unexpectedly long.
“Testosterone primes or changes the hair bulb,” endocrinologist Dr. Bradley Anawalt told The New York Times. Potentially beginning as early as one’s 40s, men, in particular, may begin to notice these changes in their terminal hairs. This growth may not only occur inside the nostrils, but also in other places (such as on the nose itself).