For the most part, people do not retain reflexive consciousness while dreaming. But for reasons unknown, people can, occasionally, regain consciousness while dreaming—a phenomenon called lucid dreaming. In spite of one-time skepticism as to the existence of lucid dreaming, its veracity has been confirmed by volitional eye movement signals recorded via electro-oculogram during REM sleep.
During lucid dreams, a person realizes that they are in the midst of a dream but remain physiologically asleep and submerged in a dream environment. Lucid dreamers are aware of their own state of consciousness, and can frequently regain episodic memory and control of actions as well.
Here is some more information about lucid dreaming, including its link to mental illness.
Frequency. Although most people rarely experience lucid dreams, there is variation in the frequency of this phenomenon. Specifically, about 50% of people never lucid dream, 20% have lucid dreams monthly, and a small number experience them weekly or even daily. Such variations raise the prospect that individual differences in brain physiology and anatomy may account for lucid dreaming.
Mechanism. The prefrontal, parietal, and lateral middle temporal cortices demonstrate decreased regional cerebral blood flow during sleep, including REM sleep—the sleep stage tied to dreaming. Experts hypothesize that hypoactivity of these regions results in decreased awareness and volitional control while dreaming.
Conversely, hyperactivity in these same regions, in the form of increased signaling—specifically in the anterior prefrontal cortex, bilateral inferior parietal lobule, precuneus, and inferior and middle temporal gyri—can result in lucid dreaming. Limited and low-power EEG and functional MRI findings support this hypothesis.
Additionally, evidence associating frontopolar and parietal regions to lucid dreaming supports the metacognitive functions of these regions, with the anterior or prefrontal cortex playing a crucial role in the neuroanatomical foundation of metacognitive processes, such as self-reflection and the evaluation of thoughts and feelings.
Differences in metacognitive function among individuals have been tied to differences in gray matter volume in the anterior prefrontal cortex. And patients who experience damages at the level of the anterior prefrontal cortex experience metacognitive deficits—including the inability to monitor disease symptoms or accurately judge cognitive abilities—that are akin to those seen in non-lucid REM sleep
Recent research findings indicate that regular lucid dreaming is significantly linked to heightened functional connectivity between the anterior prefrontal cortex and temporoparietal association areas, which are usually less active during sleep. Other research has demonstrated that lucid dreamers display increased gray volume matter at the frontal pole (or anterior portion) of the brain. These findings lend some credence to differences among individuals that are necessary to achieve metacognitive awareness at the initiation of lucid dreaming.
Link between lucid dreaming and mental illness. Interestingly, the patterns of electrical brain activity during lucid dreaming are similar to those produced by psychosis (eg, schizophrenia), depersonalization, and pseudoseizures. Like lucid dreaming, these conditions entail an abnormal disconnect to consciousness.
In the past, the use of dream therapy in clinical scenarios has been discredited, but emerging dream research has piqued interest in this therapeutic strategy. Sussing out similarities between lucid dreaming and psychiatric conditions may open the door to novel therapeutic alternatives for mental illness. Moreover, patients with certain conditions, such as chronic nightmares, could be trained to lucid dream and wake themselves as needed.
Lucid dream induction. In the lab, researchers have attempted to induce lucid dreaming through individual or combined strategies. These approaches involve cognitive and behavioral activities intended to boost the chances of lucid insight during the dream state.
For most physicians, lucid dreaming peripherally touches on clinical practice. It’s unlikely, for example, that a primary care physician will be asked about lucid dreaming during a clinical visit. Nevertheless, as scholars of the body and mind, you may take an interest in phenomenon. Moreover, if a patient does ask, you will be informed.
As such, the science behind lucid dreaming is still largely unexplored. But the possibilities it may present are exciting.
"On the one hand, basic dream researchers could now apply their knowledge to psychiatric patients with the aim of building a useful tool for psychiatry, reviving interest in patients' dreams," continues Professor Silvio Scarone, Università degli Studi di Milano, Milan, Italy. "On the other hand, neuroscience investigators could explore how to extend their work to psychiatric conditions, using approaches from sleep research to interpret data from acute psychotic and dissociated states of the brain-mind."