The Reality Sense in Dreams

When we dream we are utterly and completely convinced that the events and things we experience in dreams are real. We are not aware that we are asleep. I once had a dream where I was shouting something as loudly as I could. The effort was so real that I woke up and I had the distinct sense that I must have been shouting/talking in my sleep—but my bedpartner at the time denied any sleep talking-- never mind shouting. The standard explanation for delusional mis-identification of dream-events as real is that the dorsal prefrontal lobe is down-regulated or de-activated during REM and it is this brain region that mediates the reality sense during waking life. The dorsolateral prefrontal (dlPFC) cortex is thought to mediate self-reflection, insight, self-monitoring and attention. Thus, if the dlPFC is turned off during REM then it is not surprising that insight, self-reflection, and self-monitoring functions would be deficient during REM. Without normally functioning self-monitoring occurring in dreams we mistake dream events for real events. But there are several problems with this standard explanation for impairment of the reality sense in dreams. 1) If the impairment of the reality sense is due to down regulation of dlPFC during REM then you would expect that the reality sense would vary with activation levels of the dlPFC. But instead we find that the reality sense is virtually always impaired or even absent in dreams. There is little or no variation in that “impairment”. We virtually always accept dream events as real when we are dreming them. 2) The dlPFC is not down-regulated during NREM N2 sleep-yet the reality sense is still impaired during N2 dreams. 3) Self-monitoring functions are NOT entirely absent in dreams--yet we always accept dream events as real. Many dream content studies have shown that dreamers typically use self-critical and self-monitoring faculties in dreams. Dreamers problem solve in dreams, they can detect deception in other characters. They can mind-read minds of other characters. They can reflect on their own emotions, behaviors, actions and responses in dreams. Yet, despite all of this critical reflectiveness in dreams we still accept dream events as real. So, if impairment of the reality sense is not due to impairment in self-monitoring faculties or to down regulation of the dlPFC what causes us to accept as real the events which occur in dreams? One possibility is that the dream events are in fact real in some sense. That possibility however entails a re-evaluation of reality itself so lets set that aside for now. Another possibility is that the perceptual senses are what causes us to experience events as real during waking life and dreaming. The sense of reality is a direct result of perception, of perceiving something. While most scientists would agree that perception causes the reality sense during waking life they will point out that the senses are at least partially blocked during sleep so they cannot be related to the reality sense during dreams. But it has become increasingly clear that not all of the senses are blocked during sleep. Some somatosensory, aesthetic, sound, smell, visceral sensations can and do reach the cortex during sleep. Visual information on the other hand undergoes substantial blockade. The sleeping brain may not be entirely isolated from the outside world, though it is clear that there is a significant sensory attenuation during sleep. Given the partial though significant sensory attenuation that occurs during sleep direct perceptual experience cannot explain the reality sense in dreams. Another possibility is that the sensory association areas in the cortex are highly activated during REM. There is therefore likely to be intense processing of sensory information during sleep. That information may not be entirely current. It may be composed of sensory residue from the previous day. It in any case may be treated by the brain as recent sensory information. If that is so then that would explain why the dreamer takes dream-world as a real world. None of the foregoing explanations are entirely satisfactory. We still do not know why we accept as real the events we experience in dreams.