For most of the subjects, their first, second and third dreams were very abstract and seemingly difficult to see any meanings, or messages. These early dreams, also, have a very slim chance of being remembered when one awakes. In most cases, and probably holds true for all of us, the last dream we have is the one we will most likely remember. Basically, your subconscious will create a dream around these events, so your mind is 'tricked' into thinking these disturbances are merely part of the dream. In a way, this type of dream acts as a protective shield, allowing the physical body to continue sleeping undisturbed.
Subconscious dreams are mostly symbolic, or a picture language, which needs to be interpreted.
They often reflect upon conditions of the body, often symbolized by vehicles - and even the emotions, often symbolized by elements of water. These dreams are to help us become aware of our problems, and bring assistance in solving them. Most of our dreams fall into this category. Clairvoyant dreams are usually classified as visions, spiritual experiences, or revelations. ESP dreams, and those that preview the future come into this category also.