Dream: the temporary cessation of the waking state.

1. From time to time in this period anything from a single picture or figure to an elaborate story may be vividly perceived, which is in no sense a direct perception of the outer physical world. This happens 4 or 5 times per night.
2. In addition there are periods of conceptual activity or thinking between dream periods. [Parts of the brain never go to sleep].
3. A third form of dream is the spontaneous image or vision that appears to a person in the borderland or wakefulness when a person is not sure they are awake or asleep.
4. The waking dream or vision consists of dream images that intrude into waking consciousness. The images are not different than the ones in sleep.

From God, Dreams and Revelation – Morton T. Kelsey