As far as dreams were concerned—well dreams are generated by the random processes of neural oscillation during the brain’s rest phases. What dreams do is cycle and recycle images and feelings, rationalisations and fears. There’s nothing special about that. It’s not the that matter (chaff, mental turbulence, the rotating metal bars moving endlessly through the transparent tub of metaphorical slushy). It is what the problem-solving circuits in the mind of the dreams. Dreams iterate and test mental schemas, discarding the maladaptive to return the adaptive to the slush to be reworked. Dreams are emotional preparations for solving problems—that is why we have evolved them, because problem-solving abilities are adaptive and thus strongly evolutionarily selected. Dreams intoxicate the individual out of reliance on common sense and preconception, and tempt her into the orbit of private logic. Dreams have utility.
Adam Roberts