I have a keen interest in Jungian psychology. In his biography Memories, Dreams, Reflections Jung talked about venturing into his own Unconscious mind with a conscious cognitive thinking mind. This is most unexpected from a once disciple of Freud whose psychoanalysis is scientifically oriented. How can one have conscious cognitive thinking in dream? How can one venture into his owe Unconscious mind with (almost) total consciousness? His little book of “Divine revelation” Seven Sermons to the Dead raised eyebrows in the academic community. Jung later said to have regretted publishing this little book of revelation. He did not know where he should stand: scientific respectability or spiritual (or Divine) truthfulness. So much so, there are now two interpretations of Jung: a great psychologist or a great Gnostic (knowledge of transcendence arrived at by way of interior, intuitive means.) And both have followers.
Another major character in our intellectual history is great modern philosopher Nietzsche. His Thus Spoke Zarathustra spoke the language of a person in a deep meditative state in which the meditator’s conscious mind is functioning, co-existing with his Unconscious mind. It was functioning well in the case of Nietzche. Nietzsche faced dilemma similar to Jung. Like Jung he did not want to suppress or deny the meaning of his inner experience, he rationalized it with the reason that the obscurity of his language is to safeguard his great teaching from the people who do not deserve to have such great teaching revealed to them! His Will to power is his morality in direct opposition to Christianity (unlike Jung, Nietzsche's writings are quite muddled and therefore inaccessible to common readers. A good source to understand Nietzsche is Bernard Reginster's The Affirmation of Life - Nietzsche on overcoming nihilism). Yet, he refrained from setting rules of morality, otherwise he will be viewed as a spiritual leader rather than a philosophy, though I suspect that there will be folks who would consider Nietzsche a spiritual leader.
What has that got to do with meditation? You might ask.
For meditators or chi king practitioners who have come to a stage in which he can speedily get into a whole body chi-filled condition when he relaxes, he might encounter similar direct experience. When he falls asleep, since he is relaxed, his body will still be chi-filled. And in deep meditation, since he is relaxed, his body will be chi-filled too. And since his body is in chi-filled state, his conscious mind will still be working, to a certain extent. And the fact that he is asleep or into deep meditation his Unconscious mind will surface. In short, both his conscious and Unconscious mind will be working at the same time! The resulting experience is an interaction between his conscious (rational) and Unconscious (irrational) mind. And from there came Seven Sermons to the Dead and Thus Spoke Zarathustra.
On the experiential perspective, it is called vivid dream. Vivid dreams are rich in details and as Jung (and Nietzsche too, without himself being explicit about it) experienced, one’s conscious mind is at work. And at work in such a way that our conscious mind can ask logical questions and explore problems; and in a way that one can sometimes even know that one is dreaming (in Jung's case, knowing he was in the realm of his own Unconscious)! At the same time, our Unconscious mind will exert its impact by trying to “convince” our conscious mind to “accept” conclusion loosely “answered” by images and illogical events. In short, vivid dreams are enlightening but often giving us images or "not-totally-logical" arguments instead of definite answers to our problems.
Needless to say only great mind can produce great insights. Common meditators can benefit from such inner experience with some insights and reflections. Pompous people might have the danger of getting themselves into a state of over-confidence. Superstitious people might become more superstitious. And those with inherent mental problems might have a psychotic onset!