Both Sigmund Freud and Carl Jung integrated dream analysis into their analytical work with clients, and saw dreams as a vital component of psychological growth and health. Jung's contributions to dream psychology came to be even more encompassing than Freud's, and he developed a much broader spiritual understanding of dreams and the connectedness between us all. Jung's dream concepts have not only been integrated into many of today's psychological theories, but also form the backbone of many spiritual and self-growth schools of thoughts.
In my own dream work with clients, I place high importance on dreams, both from a psychological and spiritual perspective. We spend about a third of our lives sleeping, and perhaps as much as half of our lives (or more!) in unconscious states, and as dreams are a direct expression of the unconscious, they can indeed reveal many hidden aspects of our personalities and life situations that we are not yet aware of. Therefore, if we were to just look at what we think we are experiencing in our daily lives, but ignore what is happening in our dreams, we would miss out on highly valuable information! By listening to our dreams, we integrate all aspects of ourselves and are able to form a more complete picture.
It is also important to remember that our egos represent only a small component of our total selves, and as a consequence, what we are aware of (our ego) will always have just a partial view of life because of limited consciousness, so the importance of dreams cannot be emphasized enough. By looking closer at your dreams, you not only learn more about what is really going on in your life, but you also develop new attitudes and perspectives on situations. You may, for example, not be aware of feeling upset about something, but then a dream helps shed light on the issue, and instead of forming an emotional blockage, you are now able to clear it out by processing the situation.