Notes from NOVA: What are dreams?

This documentary examines the question whether dreams are meaningful or not, from a scientific point of view.

It turns out that sleep is a process that proceeds in stages from wakefulness to the deepest level of sleep, level 4. Sleep cycles among those stages:

* Dreams occur during all stages, but they differ in quality. REM dreams are the longest, and the most complex.
* Areas of the brain that are active during dreaming: amygdala, right inferior parietal lobe and much of the right hemisphere.
* Anecdotal evidence points to numerous insights an solutions occurring in dreams - science and art.

The conjecture (rephrased by me) is that dreaming is an information processing state of the brain where new facts are being assimilated into the existing data model in the brain, by building links between these new facts and existing data networks. This includes sensory, intellectual and emotional information.

My enduring thesis about the functioning of the brain is that it is a problem-solving machine. It runs an evolving data model populated by external facts that are continuously being linked to each other in new semantic and procedural relationships. Facts can be visualized as nodes on a graph, with relationships as edges between these nodes, where each edge has a label that represents the quality of the relationship. The label is itself another node - or cluster of nodes.

During sleep, the brain retrieves the newly-created nodes (obtained through sensory input) and works on creating new edges that link those nodes to existing node clusters.

The result of this operation is a kind of data network, that can be activated by substituting any node with a hypothetical value. The value is then propagated through the network, transformed by each relationship, until it reaches a desired end value or shows no promise of doing so (e.g. by being stuck in a loop). This is the simplest form of problem solving.

Personal experience

My own subjective experience worth relating concerns the consciousness stage immediately preceding sleep - day dreaming if you will. While in it, I often perceive a stream of thought that runs parallel to my conscious thinking, and with which I (my consciousness) can communicate. This stream is qualitatively different than consciousness; I can describe it best as being "poetic" or "creative". It delivers meanings through analogies, not by stating facts. I communicate with it by thinking of a topic, reaching a question of interest, and then "watching" the stream to pick up any utterance. When I am able to induce this watchfulness, the utterance rarely fails to occur, and it invariably brings a new angle to the conscious topic being pondered - often an interesting and rich angle.


* NOVA | What Are Dreams? official web site
* The science of dreaming web document