Borderline personality disorder
People with BPD sometimes act impulsively because it gives them instant relief from their emotional pain. However, in the long term, people with BPD go through more pain from the shame and guilt that follow these actions. A cycle often begins where people with BPD feels emotional pain and acts impulsively to relieve that pain. Then they feel bad about what they did, and have strong urges to act impulsively to relieve the new pain. As time goes on, impulsive behavior may start to be an automatic reaction to emotional pain.