I moved my eyes, and I realized that I was asleep in bed. When I saw the beautiful landscape start to blur, I thought to myself, “This is my dream; I want it to stay!” And the scene reappeared. Then I thought to myself how nice it would be to gallop through this landscape. I got myself a horse ... I could feel myself riding the horse and lying in bed at the same time.
So recounted a test subject in the sleep laboratory at the University of Bonn in Germany. This particular sleeper was having a lucid dream, in which the dreamer recognizes that he or she is dreaming and can sometimes influence the course of the dream. By measuring the brain waves of lucid dreamers, my colleagues and I are gaining a better understanding of the neural processes underlying this state of consciousness that exists between sleep and waking. In addition to providing clues about the nature of consciousness, research on lucid dreams is also beginning to suggest new ways to treat anxiety and learn complex movements while asleep.
Most people report having a lucid dream at least once in their life, and a small fraction of us have them as often as once or twice a week. Some individuals even develop routines to increase their chances of having a lucid dream [see box on opposite page]. But researchers who wanted to study lucid dreams were long confounded by the need to rely on subjects' self-reports. The process of recall is notoriously prone to distortion; for example, some people may confuse lucid dreams with the transient hallucinations that occur while falling asleep or waking up.
In the mid-1970s some pioneers in the sleep research field figured out a way to prevent such misinterpretation. The researchers instructed subjects to move their eyes a certain way as soon as the sleepers recognized that they were dreaming, for example, by rolling their eyes twice from left to right. These signals can be easily distinguished from the rapid eye movement (REM) that occurs randomly during dreams. We still use this method today.
After a sleeper has signaled with eye movements that a lucid dream has started, researchers can investigate the corresponding brain activity using electroencephalography (EEG). In an EEG recording, electrodes attached to the skin of the head pick up the oscillating electrical signals that indicate that thousands or millions of neurons are firing in synchrony. Recent studies indicate that the brain's activity during lucid dreaming resembles that of waking consciousness.
In 2009 my team and I decided to take a closer look at the brain activity of lucid dreamers. In the sleep laboratory, we found what we believe to be an electrical signature of lucid dreaming—increased activity in the 40-hertz range (the “gamma band”), primarily in the frontal lobe, located behind the forehead. We tend to generate these high-frequency waves when we concentrate on a particular object. In addition to the frontal lobe, other regions of the cerebral cortex—the rippled mantle on the surface of the brain—play a major role in lucid dreaming. The frontal lobe seems to work in lucid dreams much as it does in the waking state.
Another striking feature in our study involved coherence—a rough measure of how coordinated the activity is in various areas of the brain. Coherence is generally slightly decreased in REM sleep but not during lucid dreams. Think of the brain's activity during REM sleep as equivalent to a party with all the guests talking simultaneously. In lucid dreams, however, the party guests converse with one another, and the background noise decreases.
Until recently, most experts thought of lucid dreaming as a curiosity—a fun way to act out wishful thinking about flying or meeting celebrities—but research has uncovered practical uses. Chronic nightmare sufferers often find their only source of relief is learning how to take control of their dreams. A study in Psychotherapy and Psychosomatics in October 2006 found that those who learned how to increase their frequency of lucid dreams reported fewer awful dreams, although the exact mechanism underlying the relief is unclear. Perhaps becoming aware during a bad dream allows sufferers to distance themselves emotionally from the content.
In theory, lucid dreams could help alleviate generalized anxiety or the reaction to specific stimuli (for instance, spiders) by allowing people to confront worries and frights in the safe environment afforded by knowing “it's just a dream.” Our most recent work with patients suffering from post-traumatic stress disorder suggests that learning how to control dreams reduces the fear of dreaming, boosts self-confidence and makes patients more optimistic about their ability to eventually cope with their trauma.
Beyond therapeutic applications, lucid dreaming may also improve athletic performance. According to sports psychologist Daniel Erlacher of the University of Heidelberg in Germany, athletes can internalize complex motor sequences, such as those needed in the high jump, more quickly after targeted lucid-dreaming training.
Some researchers have asked whether lucid dreams could be useful in focusing the dreamer's mind for problem-solving purposes. A small study in 2010 at Liverpool John Moores University in England suggested that lucid dreams are good for creative endeavors such as inventing metaphors but not for more rational exercises such as solving brainteasers. The lucid dreamers in the study were instructed to summon a “guru” figure, a wise character to serve as a kind of guide. Indeed, some of the subjects found their dream characters to be surprisingly helpful.
We still have much to learn about lucid dreaming. For example, we do not know under what circumstances these dreams appear most frequently or how to induce them more reliably. What we have learned is that lucid dreaming is frequent in children until around age 16, particularly in children with higher cognitive abilities. This leads us to believe that lucid dreaming occurs naturally in the course of frontal lobe integration and brain maturation. Of course, it also raises many new questions, such as whether lucid dreaming may prove useful in enhancing cognitive functioning. Lucid dreaming's potential for therapy, problem solving or pure entertainment could be limitless.