If you continue this habit, you'll develop the need to pull it, even subconsciously, or in your sleep. Stop doing that, like asap. I don't remember the name of the mental disease, but it becomes as addicting as alcohol or gambling, and it will indeed force you to be bald, and once you're bald from that type of scalp abuse, you can't fix it. But if you haven't done much damage (or any), i suggest just stop pulling your hair, pick up a different way to take out your stress, and take care of it. :]