As can be seen from the entry on hypnosis, the dream process is quite amenable to suggestion and conscious influence.
It is probably most helpful to think of this action as similar to the process of memory. In seeking information from memory we hold a question or idea in consciousness, the resulting associated memories or information being largely spontaneous.
The question held directs what information is taken from the enormous pool of memory.
A question might even call together scattered pieces of information which are then put together into a new composite, a new realisation. So the process is not only recall of existing memory, but also creative. It may also access skills, such as the ability to subtract one number from another. Because of these factors our conscious queries can influence the process of dreaming, causing them to respond. As dreams have access to our full memory, our creative potential as well as learnt skills, such response to concerns or queries are often of great value.
To make use of this, first consider the query as fully as possible while awake. Look at it from as many viewpoints as possible, talk it over with others. Make note of the areas that are already clear, and what still remains to be clarified. Just before going to sleep, use imagery to put your question to your unconscious resources. Imagine standing before a circle of gentle light—a symbol of one’s total self—and ask it for the information sought. Then, as if you have asked a question of a wise friend, create a relaxed state as if listening for the considered reply. In most cases, dreams which follow will in some way be a response to what is sought, though not necessarily in the way imagined. See dream process as computer; creativity and problem solving in dreams. ... A Guide to Dreams and Sleep Experiences