The science of lucid dreaming

The science of lucid dreaming
According to Tamás Bogdány and Péter Simor, lucid dreaming can be learnt, and frequent lucid dreamers can help us get closer to understanding the nature of nightmares or even relieve people suffering from insomnia. The two PPK Sleep Lab researchers, together with Philippe Peigneux of the Free University of Brussels, submitted an article summarizing a new framework for the study of lucid dreaming in the PNAS. The authors were asked to explain the predictive coding model notion and why it is beneficial to learn to dream consciously.

"Strange phenomena such as levitation, flying, floating, and out-of-body experiences in dreams, as well as the incredible depth of information in dream experiences, have long been of interest to scholars," says Peter Simor. Although the study on the phenomena of conscious dreaming is a narrow topic, it is equally accessible to researchers focusing on sleep, perception, or consciousness. Despite the fact that the issue has been part of scientific thought for 40 years owing to the work of American psychophysiologist Steven LaBerge, there are still many unanswered questions for researchers. Among the difficulties and constraints of empirical investigations are that the phenomena is very infrequent in the population and that its nature (occurring during sleep, at unpredictable times) makes it difficult to detect under laboratory conditions. Furthermore, a thorough theoretical background that may give a satisfactory explanation of the phenomenon, even if just because of the existence of the awareness issue, is still absent. The researchers' publication, which has recently been published in PNAS, hopes to add to this growing paradigm.

"Predictive coding" is not a new notion; it originated in information technology, says Tamás Bogdány. His approach was also employed earlier in regard to brain functioning, when Hermann von Helmholtz, inspired by Kant, studied the link between perception and prior experiences in the nineteenth century. However, it is only recently that this approach has been more commonly accepted in neuroscience, thanks to the visual information processing of the human brain, and may therefore prove useful in psychology as well. According to the predictive coding (or predictive processing) approach, the comparison of our previously acquired experiences with our current experiences is ongoing and present at all levels of the hierarchy: from sensory processing to information synthesis to metacognition, we view and shape our current experience through our own internal model. This method is particularly relevant in dream study since the limited sensory inputs during sleep contrast sharply with the vivid and complex dream experiences. The strangeness of dream experiences generally stems from the fact that they would not be possible in reality, yet we accept them without judgment while they endure, not recognizing that we are dreaming.

Another area where predictive coding has been proven to be crucial is in the formation of the self, where the processing of stimuli from the body, known as interoception, plays a role. This research combines our understanding of body stimuli, self-awareness, and dream experiences with the framework of predictive coding. Interestingly, prior years of psychophysiological study on interoception at the PPK under the direction of Ferenc Köteles have opened up the prospect of better exploring and interpreting sensations from the body, including dream experiences. "This has shifted our focus to examining the resolution of conflicts between particular experiences of the brain, which is asleep but still active during dreams, and stimuli from the body, which is also asleep and relaxed, in a predictive coding approach," Péter Simor adds.

The following example demonstrates this: while we sleep, our muscles and bodies relax. If we need to flee from a wild animal in our sleep but our legs are not moving, our brain has two methods to resolve the conflict between the instruction to be performed (leg movement) and the sensory input (a sleeping, relaxed leg): It either generates the sensation that our leg movement is hampered (we are walking in water or our leg is chained) or it amplifies the execution command until it bursts through the flaccidity of the sleep body, at which time we kick forcefully and are likely to wake up. According to the authors, this perspective on predictive coding in the relationship between signal processing and lived experience, as well as the absence of conflict itself (when sensory input information is temporarily not processed, it does not cause conflict, and thus we are free to run around in our sleep), can help us understand our subjective reality during both sleep and wakefulness. They expect that studying lucid dreaming will aid them in this endeavor.

Lucid dreaming as an activity can be useful not only in the laboratory: starting from the previous example, as long as we resolve a sensory conflict caused by escaping in a nightmare by waking up (or worse, being trapped in a dream), conscious as a dreamer, we have the opportunity to recognize the dream-nature of our experiences, to intervene in our own dreams, and to magically transform the location into, say, a zoo, where we can observe the lion behind the bars of the cage in complete physical relaxation.

Lucid dreamers therefore "level up": they are aware that what is happening is what they are dreaming, and even consciously able to shape the dream story in such a way that the dream can continue by overcoming the sensory conflicts - or predictive errors - that arise.

From the above, it can be seen that the dreaming brain seems to be interested in resolving such conflicts quickly: in dreams we are rarely critical of our otherwise impossible experiences in reality, and even when we are, we often explain them away. If the conflict persists for a longer period of time, we wake up or become aware of it.

Another example of this is when we are talking to an English friend in our dream, but he suddenly speaks with perfect French pronunciation, then the prediction (he will speak English) and the surprise inside the dream (so an English person cannot speak), i.e. the elimination of the prediction error will occur in the dream, for example, by the dreamer 'realizing' that he is actually walking with a French friend (updating an element of the environment to the context), or realizing that he is dreaming (a reflection on the context, which is an update at a higher level of the hierarchy). The contradiction will definitely disappear at some level of the hierarchy, and if we are lucky, we can wake up calm and rested in the morning.

The ability to remain reflective in a dream, known as "lucid dreaming," according to the researchers, may also have an important recreational value, as it can be used to achieve extraordinary experiences without the effects of drugs, and its mental health consequences can be beneficial. In other words, lucid dreaming is similar to other methods for studying consciousness, like meditation; it might alleviate anxiety, but it may also have a therapeutic function in future nightmare problems.

The scientific investigation of lucid dreaming and the mapping of individual differences will continue in the near future with empirical experiments in cooperation with the Association of Lucid Dreamers at the Sleep Laboratory of ELTE PPK.

The original publication can be found here: 

Peter Simor, Tamas Bogdany and Philippe PeigneuxPredictive coding, multisensory integration, and attentionalcontrol: A multicomponent framework for lucid dreaming