This is called trichotillomania, a common stress response, and also described as an obsessive-compulsive behavior as it sometimes relaxes the person as they do it, usually without being aware of it. There are both behavioral/counseling approaches to this problem as well as medication approaches. You can start with an evaluation in the Counseling Center in Old Main (650-3164) or can make an appointment with one of the mental health care providers in the Student Health Center to discuss your options.