The Northwestern study participants generally could confirm upon waking that they had lucidly dreamed. But some could not recall what was said or done. How participants did report hearing questions varied; some reported that the questions or cues came from something within the dream—perhaps through a radio or, in Mazurek’s case, a video game—whereas others, upon awakening, misreported the questions they had heard while dreaming. 

Researchers call the initial cue, asking the sleeper to confirm they were in a lucid dream, the “reality check.” For Mazurek, that took place in Legends of Zelda. For another subject, as depicted in Kestin’s documentary, the “reality check” appeared as flashing lights upon her dreamed-up childhood house. The flashing lights were, in reality, coming from inside the laboratory room while she slept.

Lucid dreaming, particularly, makes two-way communication possible

The REM stage of sleep has long been studied as the key area for dreaming. Because of its role in dreaming, the REM stage, previous research has found, is also a key element to allowing for successful two-way communication between an asleep person and an awake one. 

But it’s just now that Chabani and her colleagues are discovering the potentially essential role that lucidity has in complex communication between the sleeping and the awake. Although previous studies have suggested that communication to a sleeping person can cause a physical response (such as finger tapping), this study is the first to illustrate not only more complex communication (questions and answers) but recollection upon awakening. 

Of the 57 total reported napping sessions conducted by all four research teams, 26% of the sessions resulted in a confirmed lucid dream. In almost half of those lucid dream sessions, participants answered at least one of the experimenters’ questions correctly. 

In sessions where participants failed to signal they were experiencing a lucid dream, most participants also failed to respond to any of the researchers' other questions. Lucid dreaming, Chabani says, was the key to opening dreamers to receiving information, in that it allows sleepers to be more aware of the external world.

However, that meant that the stimulations from researchers—and the pre-sleep training—were key to bridging the distance between sleep and the external world created by REM-stage sleep.

“To be aware of external stimulation,” Chabani says, “the stimulation has to be clear enough and your attention must be directed to [it].”

Even before participating in the study, Mazurek had wanted to learn how to lucidly dream. But he found it difficult until his third and final session. “During the first trial,” he says, “the lucid dream quickly fell apart” after cueing from the experimenters. More exposure and training throughout the experiment, Mazurek says, gave him an “awareness” he believes is key to reaching a lucid state while dreaming.

Studies comparing subjects who have frequent lucid dreams to those who have had infrequent ones have found no difference between the psychology of subjects, she says. But they have identified differences in creativity and “metacognitions,” or one’s awareness of one’s own thoughts. “It is possible lucid dreaming is easier with the number of lucid dreams,” Chabani says. Increased creative thinking may help a sleeping person reach the lucid dreaming state, Chabani adds. 

The scientific—and recreational—applications of lucid dreaming

Chelsea Mackey, a clinical psychology Ph.D. student at the University of Washington who was not involved in the study, finds the research to be an important contribution to neuroscience and to the idea of “interactive dreaming.” 

“It aids our understanding of the complexity of sleep and dreams by integrating novel approaches to the study of two-way communication during sleep,” Mackey says. “It has critical implications for health and well-being.”

Now a junior at Northwestern majoring in neuroscience, Mazurek is working in the lab of study author Ken Paller. Paller and his team have developed a smartphone app called Lucid, which trains users to achieve lucidity while asleep in a similar manner to Northwestern’s study participants. Once turned on, the app will wait six hours. Then, in an attempt to induce lucid dreaming in its user, it will play preset soft noises. Users are asked to fill out a dream report upon waking up to record their experiences.

Mazurek and his teammates are working on the second version of the app, which they’re hoping to release in April. 

The early results have been promising: App users tend to have lucid dreams more often than other people, Mazurek explains. And the app increases lucid dreaming induction in 40% of its users, he says.

Historically, dream reporting has been fraught with difficulty, as many people cannot reliably or coherently recall a dream after waking up. That makes the ability to communicate with a person while they’re still sleeping so promising, Chabani believes. If we see something on a physiological level in a study participant that’s interesting, such as an acceleration in their heart rate, “we could ask a subject what is happening,” she says. Her team’s new study, Chabani hopes, can offer new insight into—and a better understanding of—the dreaming world. 

Mackey agrees that the findings of the study are promising. While there is still a significant amount of work to be done in this area, she says, “this study does represent substantial progress toward identifying ways to leverage and gain valuable information from lucid dreams. I am thrilled to see future progressions on this topic.”

“If we’re able to get a technique down for lucid dream induction, the applications are wild and limitless,” Mazurek says. “There are a lot of different applications, whether lucid dreaming therapy or recreational enjoyment...I think it’s a bright future ahead.”

Hanna Ali contributing to the reporting of this story.