The condition you are referring to is known as trichotillomania, and is basically characterized by a compulsion to pull out one's hair. The patient may pull out hair from any part of the body - this includes scalp hair, eyebrow hair, eyelashes, other facial hair, and pubic hair. This often results in bald patches, due to which the patient then has a secondary problem of self esteem, since they feel embarrassed about their appearance. Trichotillomania is a rather rare condition, and is as yet not fully understood. Although there is some dispute about its categorization, it is usually considered to be what is known as an "impulse control disorder" - basically, the patient is absolutely unable to control an impulse, and performs an action for the short term relief gained from executing the impulse, in spite of knowing that it will result in long term suffering. Other conditions that are categorized as impulse control disorders are kleptomania (compulsively stealing) and pyromania (compulsively starting fires).
It is extremely unlikely that you will be able to cure this condition on your own. The problem is usually stress related, and it usually takes professional counseling to break the habit. Trichotillomania usually starts during childhood, typically between the ages of 6 and 13, but it can also start much earlier. If your child is the one suffering from this condition, you may need to look into whether there is some source of stress in the child's environment, either at home or at school, or possibly in some other place. You should of course avoid scolding your child, as this will certainly not help, and might even add to the stress. You can gently remind your child to try to control his or her impulses, but in many cases, this too is useless, due to the very nature of the condition itself - if the patient was able to control their impulses, they would.
Habit reversal training is one form of treatment that has been successful at treating trichotillomania. It basically involves training the patient to recognize the impulse to pull out their hair, after which they are taught to redirect the impulse to some other harmless activity that provides a comparable sense of satisfaction or relief. In addition, triggers may be identified, and the patient will be taught how to deal with these triggers in better ways. In some cases however, medication may also be needed to help manage stress.
answered by M W