A dream is an illusory psychic activity, particularly of a visual nature that occurs during sleep. It is essentially a psychological phenomenon with many philosophical, religious and moral implications. Scientific findings on dreams have shown them to involve perception, creative and reproductive imagination, association of ideas and images, memory and emotion. The critical powers of the mind such as reality testing and decision making are greatly impaired in dreaming, which accounts for the incoherent and chaotic nature of many dreams. In a dream the distinction between reality and imagination is totally lost or at least impaired.
Dreams can be natural or supernatural.
If they are supernatural then their origin lies in God, angels or demons. Dreams can also be induced by hypnosis. What causes dreams can seldom be traced to one well defined external or internal stimulus. Rather, they are brought about my many interacting factors of a perceptual, emotional, motivational and physiological nature. Dreaming occurs in cycles following the fluctuation of sleep stages.