Updated

It triggers some people to compulsively pluck, tweeze and pull out their hair. "Usually it's almost an unconscious urge." sufferer Christina Pearson said.

Pearson pulled out most of the hair on the side of her head after a stressful event in 1997. "When I was 12-years-old, I started pulling out my hair very severely," she said. "By the time I was 14, I was nearly bald. It wasn't until I was in my mid-30's that I actually got effective treatment."

Pearson was suffering from trichotillomania, also known as "trich." It's a relatively unknown condition and it affects about 3 to 5 percent of the population.

Click here to watch a video on trichotillomania

"Trichotillomania is an impulse control disorder; this is where people have the urge that they can't control to pull their hair out," said Allison Ashley-Koch, PhD, lead researcher at Duke Univeristy Medical Center.

Patients typically have bald spots.

"The most common site is the scalp, the eyes, the body, arms, legs, really about anywhere that there is hair is fair game for pulling," Pearson said.

Researchers say it's unclear exactly what's causes trich. But it could be environmental, genetic or both.

Doctors at Duke University Medical Center have found two gene mutations that cause trich in some families. "It's actually the same gene other resarchers found associated with tourette syndrome, which we found is also associated with trichotillomania," Ashley-Koch said.

While there is no cure for trich doctors say two effective treatments are available. Those include including cognitive behavioral therapy and SSRI antidepressants, such as Prozac, Paxil, and Zoloft, which are used to treat mood and other psychiatric conditions.