Trichotillomania (TTM)
People with TTM or trich feel an intense urge to pull their hair out and often experience growing tension until they do. After pulling their hair out, they feel a sense of relief. A person may pull their hair out in situations where they are on automatic pilot e.g. watching TV but sometimes it occurs in direct responsee to a stressful situation. Most people with trich pull out hair from their scalp, but some pull out hair from other areas, such as their:
eyebrows
eyelashes
genital area
beard or moustache
Bald patches left on the head tend to have an unusual shape and may affect one side more than the other. This condition can cause feelings of shame and low self-esteem and as a result people who experience it may try to keep their condition to themselves.
More information can be found at NHS Choices