Thread: Quick Review of the Scientific Litterature on Lucid Dreaming 2021

After recent conversations, I have decided to peruse the accessible scientific literature on dreaming and lucid dreaming to better align my understanding of the topic with the modern scientific discussion.

This post is not meant to be a comprehensive review. I only read the articles discussed here and a few more, that is, I can’t say how aligned these articles are with the wider scientific dream discussion but they did seem to be coherent together. I also did not think critically about the methodology of experiments and the weaknesses of conclusions. I gave a lot of trust to the authors just so I could get a quick glimpse. So, let’s take this with a grain of salt. Finally, I’m only going to comment on aspects of these articles that seem relevant to discussions that I have participated in or read here on Dreamviews.

For brevity, I did some copy paste here and there in my summaries. I encourage you to read these articles yourself. What do you think? Also, if you have any articles you want to share, I’m very interested!

(Article, Kahan and Laberge 2011): https://www.sciencedirect.com/scienc...a%3Dihub#b0040
(Review by Horton: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7379370/)
Here, Laberge’s team conclude that waking and dreaming processing cognition is similar as reported by the subjects. I can’t access the article but the review by Horton discusses Laberge’s paper: It claims that cognition and metacognition were significantly similar in dream and waking with some difference, the main one being we don’t recognize our experience as being internally generated while asleep. They claim metacognition can be roused and the sleeper can recognize their experience as externally generated. Interestingly, this review article also makes anti-lucidity or anti-dream control conclusions perhaps interesting to discuss.

Kahn 2019
https://www.ncbi.nlm.nih.gov/pmc/art...g-10-02676.pdf
Says that there is continuity between the dream and waking self’s emotional response to events, people and behaviours. The non-continuity is in the events and behaviours (and acceptance of these implausible events/behaviours). Emotional reaction is the same but not the reaction (because you’d recognize the scenario doesn’t make sense).

(Hobson 2009)
https://www.ncbi.nlm.nih.gov/pmc/art....32.9.1191.pdf
Hobson et al. demonstrate that lucid dream has a different brain state from REM sleep. The lucid dreaming brain state is similar to the waking state. Non-lucid REM sleep is different from lucid REM sleep and both are different from waking but lucidity leads to a voluntary change of brain state toward a waking state.

(Tononi 2010)
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2814941/
An interesting review worth reading but I just wanted to point out some parts:
Dreaming consciousness is like waking consciousness except reduced attention and voluntary control, lack in self-awareness, altered reflective thought, occasional hyperemotionality, and impaired memory.
- What determines the level of consciousness during sleep? Perhaps it’s better measured by brain response to transcranial magnetic stimulation than EEG, which may be associated with brain’s ability to integrate information.
- Are dreams more like perception or imagination? More like imagination than perception.

(Gravely and Wamsley)
https://www.apa.org/pubs/journals/fe...ps-0000018.pdf
Whereas historical models (Messages from gods, Freudian model, activation-synthesis model, AIM model) of dreaming emphasized how much of a different state of consciousness dreaming was, recent research demonstrates that dreaming is more like waking consciousness. Dreaming is not a replay of previous experiences. Like in waking daydreaming, distant and recent memory fragments combine to form novel imaginary scenarios never lived before. For example, the spontaneous (rather than random) neural activity is also characteristic of waking consciousness. In fact, they argue that there is no compelling evidence that dreams can be usefully “interpreted” in clinical practice. That is, dreams are not more symbolic than waking cognition. Instead, dreaming is best viewed as a transparent reflection of waking thoughts, feelings, and memories. They also argue that dreams do not cause memory consolidation but that rather, they reflect at the phenomenological level, memory consolidation at the neurobiological level.

(Tononi 2018)
https://www.nature.com/articles/s41598-018-36190-w.pdf
Their results suggest that frequent lucid dreaming is associated with increased functional connectivity between the anterior prefrontal cortex and temporoparietal association areas (while awake), regions normally deactivated during sleep. Interestingly, no significant differences between groups were observed for brain structure, working memory capacity, or questionnaire assessments of mind-wandering frequency, prospective or retrospective memory or trait mindfulness.
They characterize lucid dreams with self-reflection and metacognitive awareness of one own’s state of consciousness.
They note that evidence indicates that lucid dreaming is a learnable skill that can be developed by training in strategies such as metacognitive monitoring (i.e., “reality testing”) and, especially, prospective memory. Because they saw no significant difference in working memory capacity, and prospective and retrospective memory, they posit that differences in memory skills might not affect frequency of spontaneous lucid dreams, but might be useful in learning to lucid dream. Interestingly, about trait mindfulness, seems like it does not affect spontaneous lucidity either. And this seems to correspond with other studies. Except meditation. Meditation might be a good strategy but it wasn’t studied here. The type of mindfulness they looked at was decentering and curiosity. The Curiosity factor corresponds to an “an attitude of wanting to learn more about one’s experiences”, whereas the Decentering factor corresponds to “awareness of one’s experience with some distance and dis-identification rather than being carried away by one’s thoughts and feelings”

(Baird 2020)
https://www.ncbi.nlm.nih.gov/pmc/art...ms-1525230.pdf
There might be two neurobiological signatures of lucid dreaming. 1. The lucid moment switch “ah, I am dreaming”: metacognition signature and 2. potential sustained differences in brain activity between lucid and non-lucid REM sleep dreaming. This second neural signature is unlikely to be a signature of meta-awareness per se, as during lucid dreams individuals do not continuously engage in metacognitive reflection on their state of consciousness. Rather, this second signature captures the “state-shift” in consciousness that occurs from non-lucid to lucid dreaming, with enhanced volition, episodic memory and accessibility of metacognition.

They also state that all dreams are not the same and there are so many variables between individual dreams.

Training to lucid dream: prospective memory, interrupting sleep with short periods of wakefulness.

Some define a state of pre-lucid which I think is relevant: when you question things in the dream without concluding you are dreaming, or doing impossible things.

Overall, these data suggest that the pattern of brain activation observed during dreamed motor execution overlaps with motor execution during wakefulness. However, given the different patterns of activation, the data may also suggest that the interactions between the supplementary motor area, somatosensory and sensorimotor cortex differs between REM sleep dreaming and waking. The authors suggest that the reduced activation in sensorimotor cortex could be due in part to the lack of sensory feedback as a result of REM sleep atonia.

Some eye movement studies show that dreaming is more like waking perception than imagination in that aspect.

(Robert 2012)
https://idea.library.drexel.edu/isla...ct/idea%3A3853
While waking mindfulness is related to dream mindfulness, it is not correlated with lucidity. Alternatively, while high levels of attention, reflection, volition, self-awareness, and control are often observed in lucid dreams, they may not be exclusive to lucid dreams.

(Tononi 2019)
https://www.ncbi.nlm.nih.gov/pmc/art...ms-1024341.pdf

Long term meditation is associated with more frequent lucid dreams, and only among meditators is there an associate between lucid dream frequency and mindful waking traits: observing, non-distraction, non-automaticity and decentering (observing thoughts and mental events as mental events, opacity of mental states).

Quick Conclusion

I would like to direct intention toward three things: The continuity hypothesis (dream cognition is continuous with waking cognition), the mindfulness-lucid gap : waking mindfulness is continuous with dream mindfulness but neither were associated with lucid frequency in non practitioners (to me this means, that while mindfulness might help a lucid dream practioner get lucids, one does not naturally cause the other. This also why we often talk about semi-lucids, because we can have a lucid dream (metacognitive event) during a low mindfulness dream period and vice versa. In the Hobson study with lucid practioners, the authors posit two biological signatures of lucid dreaming, one associated with the aha moment and one associated with the brain state being more alike waking (mindfulness perhaps). So, the mindfulness-lucidity gap that there are two general component to "lucid dreams", Recognition of External/Internal generated items when impaired, is the critical trait of non-lucid dreaming.

I'm really interested in any discussion that might sprout from these articles and from others, but I wanted to emphasize these to support another thread I want to make and I will link here once it is posted: In-Out Tagging