Neuroscience Blog

Written by Brett Weiss

May, 2019

            Dreams, like hallucinatory experiences, induce profound effects of perception, visual imagery, emotional activation, along with fear extinction.  One might view lucid dreams as ‘special’ types of dreams in that waking awareness occurs during the dreaming state.  Thus, a dreamer who experiences lucid dreams has the ability to explore the dreamscape from an awakened point of view and possibly manipulate various aspects of the dreamscape such as what appears in the dream.  Not everyone has lucid dreams, though.  What neurological distinctions exist when comparing those who experience lucid dreams from those who have typical dreams?  The article will explore research related to brain structure and brainwaves while dreaming in those who experience lucid dreaming compared to ‘typical’ dreamers.  Potential therapeutic value of lucid dreaming will also be explored.

            Dreamers have metacognition during lucid dreams.  Metacognition entails reflecting on and reporting mental states (Filevich et al., 2015; Schooler, 2002).  In contrast to mental states during wakefulness, during ‘typical’ dreaming, metacognitive mental processing does not occur.  Rapid eye movement sleep (REMS), the sleep state in which dreams most frequently occur, involves deactivation of frontal regions of the brain (dorsolateral prefrontal cortex and frontopolar cortices).  Researchers have implicated these frontal regions of the brain in metacognitive mental monitoring (Filevich et al., 2015).  In contrast to REM sleep, the rare condition of lucid dreaming allows some dreamers to regain their metacognitive abilities to reflect on their current state of consciousness.  While muscular atonia (a lack of motor movement capabilities during REMS and lucid dreaming) prevents motor behavior, lucid dreamers have communicated their state with volitional eye movements in studies utilizing an electrooculogram (Filevich et al., 2015; Hearne, 1978; La Berge et al., 1981).  Two studies used this method to identify onset of lucid dreaming.  Voss et al. (2009) found that brainwave frequencies of electroencephalogram activity in frontal regions of the brain during lucid dreaming facilitated “hybrid” features of REMS and wakefulness.  Dresler et al. (2012) showed higher blood oxygen level-dependent (BOLD) activity in frontal regions (right prefrontal cortex and bilateral frontopolar areas) in lucid dreams compared to REM sleep.  Previous research has associated these frontal regions with metacognitive abilities; and thus, increased activation of these prefrontal cortical regions characterizes lucid dreaming.  During typical REMS, activation of these prefrontal regions decreases (Filevich et al. 2015; Maquet et al., 1996).  Filevich et al. (2015) did a brain structure analysis of ‘high lucidity’ dreamers and compared them to ‘low lucidity’ dreamers.  Participants in the ‘high lucidity’ group showed greater grey matter volume in a region toward the front of the brain in the prefrontal cortex (frontopolar cortex).  Hence, this study correlated increased grey matter in a brain structure involved in metacognition to a group of frequent lucid dreamers, the ‘high lucidity’ group.  Their results point to common neural systems between lucid dreaming and metacognitive processing, thought monitoring in particular. 

            Lucid dreaming may have therapeutic value.  Dreams represent simulations of reality, and the replay of traumatic events in dreams can instigate fear extinction.  The simulations during dreams provide bizarre and fictitious settings wherein the replay of traumatic events lessens the burden associated with emotional trauma (Scarpelli et al., 2019).  Studies have shown that transcranial alternating stimulation applied to the frontal area of the brain (frontotemporal area) in the gamma band brainwave frequency can initiate lucid dreams during REMS (Scarpelli et al., 2019; Voss et al., 2014).  Initiation of lucid dreaming during REMS might prove useful in processing traumatic memories.  Lucid dreams in processing traumatic emotional memories may allow for altering dream contents so that they become neutral, thus making the contents non-disturbing or even positive.  Initiating lucid dreaming may also provide an intervention for nightmare disorder (Zadra and Pihl, 1997; Spoormaker et al., 2003; Spoormaker and Van den Bout, 2006; Scarpelli et al., 2019).

            Lucid dreams constitute rare dream states whereby the dreamer has metacognitive abilities of a dreamscape.  Activity in frontal regions of the brain during dreaming distinguish this dream state from typical dreaming.  Evidence suggests neural correlates of ‘high lucidity’ dreamers– increased grey matter in frontal regions (frontopolar cortices).  Initiating lucid dreams for neutralizing traumatic memories and nightmares may prove beneficial therapeutically, although scant research currently exists on this new idea.

References

1.  Dresler M, Wehrle R, Spoormaker VI, Koch SP, Holsboer F, Steiger A, Obrig H, Samann PG, And Czisch M (2012).  “Neural correlates of dream lucidity obtained from contrasting lucid versus non-lucid REM sleep: A combined EEG/fMRI case study.”  Sleep.  35: 1017-1020.
2. Filevich E, Dresler M, Brick TR, and Kuhn S (2015).  “Metacognitive Mechanisms Underlying Lucid Dreaming.”  J Neurosci.  35(3): 1082-1088.
3.  Hearne KM (1978).  “Lucid dreams: an electro-physiological and psychological study.”
4.  La Berge SP, Nagel LE, Dement WC, and Zarcone VP Jr (1981).  “Lucid dreaming verified by volitional communication during REM sleep.”  Percept Mot Skills.  52: 727-732.
5.  Maquet P, Peters JM, Aerts J, Delfiore G, Degueldre C, Luxen A, Franck G, others (1996). “Functional neuroanatomy of human rapid-eye-movement sleep and dreaming.”  Nature.  383: 163-166.
6.  Scarpelli S, Barolacci C, D’Atri A, Gorgoni M, and Gennaro LD (2019).  “The Functional Role of Dreaming in Emotional Processes.”  Front Psychol.  10(459).
7.  Schooler JW (2002).  “Re-representing consciousness: dissociations between experience and meta-consciousness.  Trends Cogn Sci.  6: 339-344.
8.  Spoormaker VI and Van den Bout J (2006).  “Lucid dreaming treatment for nightmares: a pilot study.  Psychother Psychosom.  75: 389-394.
9.  Spoormaker VI, Van den Bout J, and Meijer EJG (2003).  “Lucid dreaming treatment for nightmares: a series of cases.”  Dreaming.  13: 181-186.
10.  Voss U, Holzmann R, Tuin I, and Hobson JA (2009).  “Lucid dreaming: a state of consciousness with features of both waking and non-lucid dreaming.”  Sleep.  32: 1191-1200.
11.  Voss U, Holzmann R, Hobson A, Paulus W, Koppehele-Gossel J, Klimke A, et al. (2014).  “Induction of self-awareness in dreams through frontal low current stimulation of gamma activity.”  Nat Neurosci.  17: 810-812.
12.  Zadra AL and Pihl RO (1997).  “Lucid dreaming as a treatment for recurrent nightmares.”  Psychother Psychosom.  66: 50-55.