Monday, 1 August 2016

Neuroscientific Studies into Lucid Dreaming

Lucid dreaming is simply the ability to recognise that you are asleep and dreaming i.e. conscious awareness in the dream state. 

We spend around 6 years of our lives dreaming – approximately 2,190 days or 52,560 hours. Although it is possible to be aware of the perceptions and emotions we experience in our dreams, we do not have the same levels of consciousness as in the waking state, which explains why we do not usually recognise that we’re in a dream and often mistake these bizarre narratives and events for reality.

Alternatively, lucid dreamers have the ability to experience awareness during their dreams by ‘re-awakening’ or activating some aspects of their waking consciousness, sometimes with the additional ability to take control and act with intention in the dream world. Dream control is not necessary for lucid dreaming, but it is the one aspect most amateur oneironauts focus on, and is typically viewed as the main attraction for those wishing to learn how to induce lucidity.

Lucid dreaming is still an understudied subject, but recent advances suggest it’s a hybrid state of waking consciousness and sleep. However, a number of recent neuroscientific studies have focused on this phenomenon, in the hope that light can be shed on how lucid dreaming, human consciousness and brain activity are linked.

Lucid dreaming is one of many ‘anomalous’ experiences that can occur during sleep. Sleep paralysis, where you wake up terrified and paralysed while remaining in a state of sleep (sometimes experiencing hallucinations) is another. There are also false awakenings, where you believe you have woken up only to discover that you are in fact dreaming – this phenomenon also coinciding with the experience of sleep paralysis. Along with lucid dreams, all these experiences reflect an increase in subjective awareness while remaining in a state of sleep. 

Approximately 50% of us will experience at least one lucid dream in our lifetime and scientists are starting to accept evidence that lucid dreaming can be intentionally induced through various techniques and methods.

A recent study (Voss et al, ‘Measuring Consciousness in Dreams: the Lucidity & Consciousness in Dreams Scale’ (2013) Consciousness & Cognition, 22(1), 8 – 21) asked subjects to report in detail on their most recent dream. 

Researchers found that lucid (compared to normal, non-lucid) dreams were indeed characterised by far greater insight into the fact that the sleeper was in a dream. Subjects who experienced lucid dreams also said they had greater control over thoughts and actions within the dream; had the ability to think logically, and were even better at accessing and reflecting on real memories of their waking life.

Another study (Dresler et al, ‘Volitional Components of Consciousness Vary Across Wakefulness, Dreaming & Lucid Dreaming’ (2014) Frontiers in Psychology) analysed subjects’ ability to make conscious decisions in waking life as well as during lucid and non-lucid dreams. The study found a significant degree of overlap between waking volitional abilities and those experienced in lucid dreaming. However, researchers found that the ability to plan was considerably worse in lucid dreams compared to wakefulness.

Lucid and non-lucid dreams certainly feel subjectively different, suggesting that these dream states are associated with different patterns of brain activity. However, scientifically confirming this is not as easy as it might seem, as subjects are required to be positioned in a brain scanner overnight and researchers have to decipher when a lucid dream is happening so that they are able to reliably compare brain activity during the lucid dream with that of non-lucid dreaming. 

Many ingenious studies examining this link have devised a communication code between lucid dreaming subjects and researchers (during Rapid Eye Movement (REM) sleep, when dreaming typically takes place). Before going to sleep, the subject and the researcher agree on a specific eye movement (i.e. 2 movements left, then 2 movements right) that subjects will make to signal that they are lucid.

Using this approach, studies have found that the shift from non-lucid to lucid REM sleep is associated with an increased activity of the frontal areas of the brain (Voss et al, ‘Lucid Dreaming: A State of Consciousness with Features of Both Waking & Non-Lucid Dreaming’ (2009), Sleep, 32(9), 1191 – 1200). 

Significantly, these areas of the brain are associated with ‘higher order’ cognitive functioning, for example, logical reasoning and voluntary behaviour which are typically only observed during waking states. The type of brain activity observed (gamma wave activity), is also known to allow different aspects of our experience; perceptions, emotions, thoughts, and memories to ‘bind’ together into an integrated consciousness. 

A follow-up study (Voss et al, ‘Induction of Self-Awareness in Dreams through Frontal Low Current Stimulation of Gamma Activity’ (2014) Nature Neuroscience, 17, 810 – 812) found that electrically stimulating these areas caused an increase in the degree of lucidity experienced during a dream.

A further study (Dresler et al, ‘Neural correlates of dream lucidity obtained from contrasting lucid versus non-lucid REM sleep: a combined EEG/fMRI case study’ (2012), Sleep, 35(7), 1017 – 1020) was able to more accurately specify the particular brain regions involved in lucid dreams. Researchers found increased activity in regions such as the pre-frontal cortex and the precuneus, these brain areas being associated with higher cognitive abilities such as self-referential processing and a sense of agency. Again, these findings support the view that lucid dreaming is a hybrid state of consciousness.

A recent study, E Filevich et al, 'Metacognitive Mechanisms Underlying Lucid Dreaming' (2015) The Journal of Neuroscience, 35(3), 1082 - 1088 has sought to determine if subjects with high and low dream lucidity also displayed differences in their waking metacognitive skills - i.e. the ability to reflect and report on their mental states.

Subjects completed questionnaires on the frequency, intensity and degree of control in their lucid dreaming experience and also their metacognitive abilities/skills, including self-reflection and self-consciousness. They then underwent brain imaging while performing a thought monitoring task which consisted of two 11 minute during which the subjects had to evaluate every thought which entered their minds on an externally-internally oriented scale. Externally-orientated thoughts related to thoughts influenced by the environment - such as sights/sounds; while internally-orientated thoughts involved those which are not related to the immediate environment, such as memories or abstract ideas. 

The research highlighted that subjects with high/low lucidity were different. Subjects with high lucidity in their dreams had greater grey matter volume in their frontopolar cortex compared to subjects with low lucidity. This region of the brain was shown to have greater levels of activity during thought-monitoring tasks performed by both the high/low lucidity subjects, with stronger increases in the high lucidity group. This enabled the researchers to conclude that lucid dreaming and metacognition share some underlying mechanisms, particularly those related to thought-monitoring. This is unsurprising, and this relationship had been previously suspected, but not tested on a neural level. 

The finding from these studies represent another exciting breakthrough in understanding the science of lucid dreaming, and further steps towards understanding the neuroscience of lucid dreaming and consciousness. 

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