The psychologists Carl G. Jung and Sigmund Freud discovered that supressed and unprocessed experienced are stored in the subconscious. But they are stored in pictures, not in words. Especially children often do have not the right words to explain what happened, they cannot communicate and explain their feelings. But they can through drawings. Experiences, emotions and feelings can be expressed through art work and thus communicated.
Furthermore, through creative work own ideas are transformed into something individual which creates emotional stability and more confidence.