Conscious in Dreamland: The Neuroscience of Lucid Dreaming
I do a lot of weird things while sleeping. I talk, walk, and experience vivid dreams, all without conscious awareness. Despite the fact that my dreams are often absurd, I don’t question their content while I’m in them. (Oh, I’ve been hired to make a documentary about Philadelphia Eagles tight end Zach Ertz and his wife Julie, a US National Soccer Team player, for ESPN’s 30 for 30 series? Of course my neuroscience background has landed me on the shortlist of filmmakers who would be considered for this position.) However, some people are able to correctly recognize that these bizarre circumstances have a logical explanation: they’re dreaming. In On Dreams Aristotle wrote, “for often, when one is asleep, there is something in consciousness which declares that what then presents itself is but a dream.” This realization unlocks a world of potential for the dreamer, limited only by imagination. Frederik van Eeden tirelessly recorded 352 such dreams over sixteen years, publishing several in a scientific paper in order to illustrate the characteristics of what he called lucid dreams.
On Sept. 9, 1904, I dreamt that I stood at a table before a window. On the table were different objects. I was perfectly well aware that I was dreaming and I considered what sorts of experiments I could make. I began by trying to break glass, by beating it with a stone. I put a small tablet of glass on two stones and struck it with another stone. Yet it would not break. Then I took a fine claret-glass from the table and struck it with my fist, with all my might, at the same time reflecting how dangerous it would be to do this in waking life; yet the glass remained whole. But lo! when I looked at it again after some time, it was broken. It broke all right, but a little too late, like an actor who misses his cue. This gave me a very curious impression of being in a fake-world, cleverly imitated, but with small failures. I took the broken glass and threw it out of the window, in order to observe whether I could hear the tinkling. I heard the noise all right and I even saw two dogs run away from it quite naturally. I thought what a good imitation this comedy-world was. Then I saw a decanter with claret and tasted it, and noted with perfect clearness of mind: “Well, we can also have voluntary impressions of taste in this dream-world; this has quite the taste of wine .”
When I first tried to investigate lucid dreams–dreams in which the dreamer is aware she is dreaming–I fell into an internet rabbit hole filled with youtubers explaining astral projections (willful out of body experiences) and websites trying to sell nootropics. Lost in the land of woo, I wanted to dig deeper into the science behind lucid dreaming, and figure out if I could train myself to wake up in my dreams. So, put on your helmets fellow oneironauts, we’re going dream exploring.
It Was All A Dream
When van Eeden coined the term lucid dreaming, he chose the word dream quite carefully. He pointed out that others wouldn’t believe that volition was possible within dreams and would assume that he must be experiencing some “sort of trance, or hallucination, or ecstacy .” We know that dreams occur during rapid-eye
movement (REM) sleep, which is characterized by awake-like patterns of brain activity (measured by EEG) and temporary paralysis of the muscles (measured by EMG), which prevents you from acting out those dreams. In order to figure out whether lucid dreams occur during REM sleep, all you’d need to do is devise a plan to recognize moments of lucidity in a polysomnogram, a comprehensive study that monitors EEG, EMG, and eye movements (EOG) during sleep. You may recognize the challenge inherent in the question. How can someone who is asleep convey that they are lucid? One brave soul tackled this project for his PhD thesis (which you can download in full here) by leveraging a part of the body that is exempt from paralysis during REM sleep, and whose rapid movements give rise to its name: the eyes . Experienced lucid dreamers were brought into a sleep lab where they were instructed to move their eyes from left to right eight times when they became aware that they were dreaming.
Once this eye-signaling system was established, it became clear that lucid dreaming occurred during unambiguous REM sleep. Lucid dreams lasted for an average of 2.5 minutes and typically occurred in the few hours just before waking, coinciding with the longest periods of REM sleep . They started anywhere from 2 to 51 minutes into a REM period, and didn’t seem to affect the quality of sleep on that night in any measurable way.
There’s another layer here that’s worth taking a quick detour to explore. Why should your eyes move in your physical body the way they do during your dream? It turns out that there’s a lot of research into REMs during sleep and their association with awake visual processing, implying their potential to signal changes in visual imagery within dreams . By leveraging lucid dreamers’ awareness and control within their dreams, researchers have found that certain dream acts translate to measurable changes in the physical body. For example, lucid dreamers who hold their breath while dreaming also do so in real life, and dreamed sexual activity is accompanied by physiological responses similar to those observed in wakefulness . Other evidence suggests that the brain activity that accompanies muscle movements performed during a lucid dream–like clenching your hand into a fist–may be more similar to brain activity during actual movements than the activity that is observed when you’re asked to imagine clenching your hand into a fist while awake . This suggests that your dream movements are more like real movements, apart from the temporary paralysis, than imagined ones.
It’s a challenge to find participants who are both willing and able to lucid dream on command in the lab, but researchers are eager to discover the patterns of brain activity associated with lucid dreaming. A couple studies have found evidence for increased activation of the prefrontal cortex during lucid dreaming, compared to normal REM sleep [6,7]. The area’s typical relative deactivation is responsible for the socially inappropriate behaviors and inability to reason logically that we sometimes experience during dreams. While we need a lot more research to confirm these findings, lucid dreaming could even be used to glean insight into consciousness itself, which remains one of neuroscience’s biggest mysteries.
Learning to wake up in your dreams
If, like me, you find the possibility of controlling your dreams appealing, you’re probably wondering, “Can I teach myself to lucid dream?” In his thesis, Hearne tried to induce lucid dreaming with a simple experiment; he told subjects he was going to spray them with water while they slept and, if they dreamed of water, that should be a signal that they’re dreaming . While subjects successfully incorporated water into their dreams of washing babies, being spit on, and even getting peed on by a cat the experimenter had let into the lab, none became lucid within the dreams . Another researcher similarly felt this was a learnable skill and, in a three-year dream-journal turned scientific paper, detailed his success with the mnemonic induction of lucid dreams (MILD) method . Essentially, after waking from a dream, you stay awake for ~15 minutes and then attempt to fall asleep into the same dream, telling yourself, “Next time I’m dreaming I want to remember I’m dreaming,” and visualizing yourself realizing you’re dreaming within that dream .
As someone whose daily life is frequently incorporated into my dreams, I’ve started implementing reality checks with the hopes I’ll perform one while sleeping. My google calendar regularly dings to inquire, “Are you dreaming?” Then, I examine the environment for logical flaws in my waking life, assuming that when I eventually perform one while asleep it’ll be clear that I’m dreaming. Once you learn about reality checks, you may start noticing that things are off in your dreams. Yes, the whole thing is very much like the movie Inception, though I haven’t gotten Leonardo DiCaprio to personally point out the inconsistencies of my dream world just yet. In a recent dream I spilled nearly a pound of shelled walnuts on my kitchen floor. Upset with my clumsiness, I no sooner thought to clean them up when they sank and incorporated themselves into the tile. I immediately realized that wasn’t the type of thing that could happen in real life and, proud of myself for so quickly succeeding in my quest to lucid dream, bragged about my accomplishment upon waking. Or so I thought. I woke up again, for real this time, and realized the walnut incident had been a dream within a dream. I was surprised to find van Eeden noted a similar feeling, having “the impression is as if I had been rising through spheres of different depths, of which the lucid dream was the deepest .” The idea of layered dreams within dreams certainly recalls Inception, and leads me to my personal biggest fear.
Life Is But A Dream
What if you can’t distinguish between real life and dreams? It hasn’t worked out so well in pop culture, be it Mal jumping to her death in Inception or Will taking Bob’s advice in Stranger Things, assuring himself he’s just having a nightmare, only to be taken over by the shadow monster. Of course, this concept isn’t new. In Zhuang Zhou Dreams of Being a Butterfly, a story from the third century BC, Zhuang Zhou dreams about being a butterfly and awakens as a man wondering whether he dreamed about being a butterfly or if he is in fact a butterfly dreaming about being Zhuang Zhou. Presumably most of us aren’t good enough architects to construct dream worlds that are indistinguishable from our own, but if you have any trouble distinguishing between what is real and not real, lucid dreaming probably isn’t for you.
One of the incredible potential upsides is the effect lucid dreaming can have on your waking life. If you’ve ever carried a grudge well into the day based on something
someone did in your dream that you know they didn’t really do (because it was in your dream), but you’re still a little mad at them for, you’re aware of the many ways in which dreams influence your mood. In the same way, a dream spent playing with an adorable kitten can set you up for a great day. Unless of course, like me, you wake up distraught that you don’t actually own that little fluffball and spiral into a depression over losing your dream kitten. (I’ll find you one day, Earl Grey!) In addition to the potential for a mood boost following excellent dreams, lucid dreaming may also help nightmare sufferers escape a scary situation by realizing it’s just a dream.
I hope one day I’ll be able to question why the FBI would go through the trouble of placing a tracker on my car only to give me a speeding ticket, but until then I’ll keep questioning my waking reality, getting plenty of sleep, chronicling my dreams, meditating, and employing any other trick I come across to help me on this journey.
 van Eeden, F. (1913). A Study of Dreams. Proceedings of the Society for Psychical Research, 26, 431–461.
 Hearne, K. (1978). Lucid Dreams: An Electro-Physiological and Psychological Study, (Ph.D. thesis). University of Liverpool, England.
 Andrillon, T., Nir, Y., Cirelli, C., Tononi, G., & Fried, I. (2015). Single-neuron activity and eye movements during human REM sleep and awake vision. Nature Communications, 6, 7884.
 LaBerge, S., & Rheingold, H. (1990). Exploring the World of Lucid Dreaming. New York: Ballantine Books.
 Erlacher, D., Schredl, M., & LaBerge, S. (2003). Motor Area Activation during Dreamed Hand Clenching: A Pilot Study on EEG Alpha Band. Sleep and Hypnosis, 5, 182–187.
 Voss, U., Holzmann, R., Tuin, I., & Hobson, J.A. (2009). Lucid Dreaming: A State of Consciousness with Features of Both Waking and Non-Lucid Dreaming. Sleep, 32(9), 1191–1200.
 Dresler, M., Wehrle, R., Spoormaker, V.I., Koch, S.P., Holsboer, F., Steiger, A., . . . Czisch, M. (2012). Neural Correlates of Dream Lucidity Obtained from Contrasting Lucid versus Non-lucid REM Sleep: A Combined EEG/fMRI Case Study. Sleep, 35(7), 1017–1020.
 LaBerge, S. (1980). LUCID DREAMING AS A LEARNABLE SKILL: A CASE STUDY. Perceptual and Motor Skills, 51, 1039-1042.