Have you ever had a dream in which you realized you were dreaming? Have you ever been able to control your dreams, consciously deciding what you want to experience? Some people are able to have dreams like this several times a week. Some can do it almost every night. Many believe it is a skill that can be learned and mastered . This phenomenon is called lucid dreaming.
A large percentage of the population has experienced some form of awareness within their dreams at least once – some studies report as much as 50% and 80% [2,3]. There is a good chance you have experienced it yourself.
“Lucid dreaming is taking control of your dreams – making them what you want them to be.” This is how Lee Nelson, a University of Calgary psychology student, explained the phenomenon to me. Lee is a friend of mine whose personal experiences with lucid dreaming spurred my interest in the subject. He first learned of the existence of lucid dreaming from a film. Online research on the subject led him to guides that help aspiring lucid dreamers commandeer their unconscious minds. For Lee, lucid dreaming held the promise of living out his fantasies. “I [wanted] to fly to Disneyland in my dreams, or save the world, or fight with Muhammad Ali.”
At night the brain cycles through several stages of sleep . Dreaming occurs most frequently in the rapid eye movement (REM) stage . In REM sleep the brain exhibits an activity pattern different from that of waking states. This pattern fits well with the cognitive characteristics of dreaming. Visual and emotional processing centres of the brain such as the primary visual cortex and the amygdala become very active . Dreams in REM sleep are visually vivid and are frequently emotionally intense [7,8], so it makes sense that these areas show high activity.
The dorsolateral prefrontal cortex (DLPFC) and the posterior-medial part of the parietal cortex, a region called the precuneus, both decrease in activity during REM sleep relative to waking [9,10]. The DLPFC is known to be involved in a range of executive functions such as attention regulation, working memory, and reasoning . The precuneus has been implicated in self-centered processing and the experience of agency . All of these behaviours have been noted to be impaired in dreaming .
Normally, we are oblivious to the fact that we are dreaming. Once in a while some of us are able to escape the confines of our impaired dreaming cognition and ‘wake up’ while still remaining asleep. In lucid dreaming, we can reflect on our own state of consciousness, focus our attention, and think logically [14,15]. Lee says dream lucidity training taught him to identify patterns in his dreams. He tries to “really pry at the dream to see what’s real and what’s not.” Recurrent settings and situations, malfunctioning clocks, and faulty light switches – these are things that can hint to Lee that he is dreaming. When he is able to pick up on these clues, he can immediately realize his situation and take control. How is Lee able to do this?
That is a question Martin Dresler is trying to answer. Dresler, a neuroscientist at Radboud University in the Netherlands, studies sleep and memory and has long been interested in lucid dreams. He had frequent lucid dreams as a child. “During that time I wasn’t even aware that it was something special”, he said. After starting a research position at the Max Planck Institute of Psychiatry in Munich, he began to think about researching the phenomenon.
In order to find the neural correlates of lucid dreaming, Dresler and his colleagues recruited experienced lucid dreamers from the internet and had them spend several nights sleeping in a magnetic resonance imaging (MRI) scanner. With MRI, his team is able to measure the movement of blood through the extensive vasculature of the brain . From this information, they could make inferences about the activity of brain structures and neural networks that correlate with lucid dreaming.
The lucid dreamers who participated in the study were instructed, upon becoming lucid, to move their eyes in a repeating left-right-left-right pattern. In addition to being scanned by the MRI scanner, the lucid dreamers were fitted with electrodes to monitor their eye movements, brain activity, and muscle tone. In REM sleep muscles lose their tone and the body becomes paralyzed except for the eyes, which move quite a bit . The movement of the eyes in REM sleep is thought to correspond to dreamed eye movements . If you look to the left in your dreams, the eyes of your sleeping body will move to the left. This allows the lucid dreamers in the study to let Dresler know they have become lucid without leaving their dreaming state. By cross-referencing the eye signals to electrophysiological measures, Dresler is able to confirm the lucid dream state. The eye signals provide specific temporal markers signifying the start and end of the lucid dream and can be used to guide analysis of the MRI data.
Dresler found certain areas, which are normally deactivated in regular REM sleep, become reactivated in lucid dreams . The areas that are reactivated seem to fit well with the phenomenology of lucid dreaming. While the DLPFC is less active in REM sleep than in waking states, it is reactivated in lucid dreaming. Its reactivation may explain the enhanced focus, reasoning, and memory apparent in lucid dreams. The precuneus also becomes reactivated in lucid dreams . This is consistent with the role of the precuneus in self-centered processing.
It is important to acknowledge a major limitation of the study. Although four participants were recruited, only one achieved a lucid state in the MRI scanner. The results were collected from two separate lucid dreaming episodes from this single individual. The experiment effectively became a case study. Thus, Dresler’s results must be considered preliminary, as they may not be representative of the rest of the population.
In studies of lucid dreaming, the sample sizes will always tend to be small. Experiments require people who are able to become lucid on a regular basis and there are very few who can. Participants have to fall asleep inside a noisy MRI scanner. The machine makes 100 decibels of noise, which is about as loud as a chainsaw in operation. Additionally, REM sleep occurs less frequently during an MRI scan. Dresler says the reason for this is unknown, but it seems “the brain doesn’t really like to have [dreams] in such harsh environments.” Thus, collecting data for these experiments requires a lot of time investment for little payoff. Dresler and his colleagues had to spend roughly 20 nights watching the scanner to record only two lucid dreams.
Despite the limitations of the study, Dresler says they had to start somewhere. He is now working on a new experiment that will solve some of the problems that made the MRI experiments so difficult. Instead of using MRI he will use high-density electroencephalography (EEG) to image the brain activity of lucid dreamers. In high-density EEG, a cap containing electrodes is placed on the head of participants . The electrodes are able to detect changes in electrical activity that is the result of neurons firing. While this technique sacrifices spatial resolution, it should make data collection easier and more fruitful.
Lucid dreaming may also be clinically useful. Some small trials of lucid dreaming treatment for nightmares have been conducted and show optimistic results [20,21,22]. Lee sometimes uses lucid dreaming in this way. “When I have a scary dream I feel like I have more control over it and [it becomes] fun.” Lee told me of one dream he had in which he found himself in a dark, rainy, dirty city. Initially the oppressive dreamscape was frightening, but as Lee took control of his dream he was able to change that completely. He started interacting with the dream as if he were a detective in a 1940s film noir. He chased after suspects while gunshots rang out in the distance. He found himself talking to people, gathering information, and trying to get to the bottom of a mystery. “It was exhilarating”, he says.
Lucid dreaming is certainly a fascinating phenomenon. It promises a way to experience almost anything one can imagine and shows us the possibilities of our own consciousness. As research continues, our understanding of this topic will improve; in the meantime, we can keep on dreaming.
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Alexander B. Kim is a student at the University of Calgary majoring in neuroscience. Alexander has spent his summers working in neuroscience labs at the Hotchkiss Brain InstituteFollow The Triple Helix Online on Twitter and join us on Facebook.