"It has a much larger impact on people than I think even most mental health practitioners understand," Dr. Douglas W. Woods of the University of Wisconsin-Milwaukee, the study's lead author, told Reuters Health. "A lot of people will look at this and say it's just a nervous habit, but it's not, really."

Forty percent of survey respondents reported having avoided social activities because of their hair pulling, 36 percent said they had avoided group activities, and 20 percent said they avoided going on vacation.

Fourteen percent said they drank alcohol to help cope with negative feelings due to hair pulling, while nearly 18 percent said they used tobacco products for this reason.

Among those who underwent treatment for trichotillomania -- most commonly drug treatment, usually with an antidepressant such as Prozac -- just 5 percent said they were "very much improved."

There is little evidence to support drug treatment of trichotillomania, Woods noted. "Probably the best option right now is cognitive behavioral therapy," he added. This is a type of psychotherapy in which a person learns to recognize and change negative patterns of thinking or acting.

The disorder can have a number of consequences for health, he added; sufferers may develop repetitive strain injury, while some who mouth or swallow their hair can damage their teeth and even develop potentially fatal balls of hair in their stomach. People may also feel guilty about not being able to stop pulling their hair, he added. "More so than anything they feel out of control."