Trichotillomania (TTM), or "trich" as it is commonly known, is an impulse control isorder characterized by the repeated urge to pull out scalp hair, eyelashes, facial hair, nose hair, pubic hair, eyebrows or other body hair, sometimes resulting in noticeable bald patches. Trichotillomania is classified in the DSM-IV as an impulse control disorder, but there are still questions about how it should be classified. It may seem, at times, to resemble a habit, an addiction, a tic disorder or an obsessive-compulsive disorder. Due to social implications the disorder is often unreported and it is difficult to predict accurately prevalence of trichotillomania; 2.5 million in the U.S. may have TTM, with a 1% prevalence rate.