The veil between dreamworld and reality may be thinner than we thought. In a new study released Thursday, scientists in four countries say they’ve shown it’s possible to communicate with people while they’re lucid dreaming. At least some of the time, the dreamers were reportedly able to respond to yes-or-no questions and answer simple math problems through facial and eye movements; afterward, some recalled hearing the questions during their dream.
Cognitive neuroscientist and study author Ken Paller and his colleagues at Northwestern University in Chicago have been studying the connection between sleeping and memory for years. It’s commonly thought that sleep is crucial to the robust storage of memories created throughout the day. But little is still understood about this process and how dreams might play a role in it.
“We are investigating dreaming to learn more about why dreams happen and how they might be useful for mental function during waking,” Paller told Gizmodo in an email. “As in our other work, we hypothesize that events of sleep cognition can be beneficial for memory function.”
One reason why it’s hard to understand dreaming is that most of us have trouble completely remembering our dreams once we wake up, much less recounting them to others. But Paller and his team have been experimenting with trying to communicate with sleepers for a long time. Their past research has demonstrated that people can be influenced by sounds from the outside world while sleeping. Other research on lucid dreamers—people who claim to have awareness and sometimes control of their dreams—has suggested that they can signal to outside observers through eye movements while dreaming (in 2018, a study suggested that these eye movements could be used to tell when a person has entered a state of lucid dreaming).
Many people are familiar with one-way communication with a sleeping person, as sleepwalking and sleep talking are common phenomena. But Paller’s team reasoned that it should be possible to have two-way communication between dreamers and awake observers and that the dreamers should be able to recall these conversations. They also theorized that this communication could be induced and replicated under the right conditions in the lab, which would be great for future sleep research. As it turns out, they weren’t the only scientists to have this idea. At least three other research groups in France, Germany, and the Netherlands had been pursuing the same goal.
“The research groups conducted studies independently, and afterwards we discovered that we had done similar studies in different countries. Then we decided to publish all our results together—cooperatively rather than competitively,” Paller said.
The study was published Thursday in Current Biology, while the work will also be featured in a PBS documentary airing on Friday (the segment can already be viewed on YouTube here).
Altogether, the study involved 36 volunteers. Some were self-professed experts in lucid dreaming, particularly a 20-year-old French participant with narcolepsy that made it possible for them to achieve REM sleep (the stage of sleep when dreams are most common) within the first minute of a 20-minute nap. Other participants had no prior experience with lucid dreaming, but Paller’s team tried to train all their subjects to begin a lucid dream when they heard a certain sound played while sleeping. Some teams used spoken words or tones to communicate; others relied on flashing lights or lightly touching the sleepers. The volunteers were also monitored through typical sleep measurements like EEG, which records brain activity.
Across 57 sleep sessions, participants were able to signal that they entered a lucid dream through eye movement 26% of the time. In these successful sessions, the scientists were able to get at least one correct response to a question via a dreamer’s eye movements or facial contortions nearly half the time. Overall, out of the 158 times they tried to communicate with a lucid dreamer during these sessions, they got a correct response rate of 18% (the most common response, around 60%, was no response).
When the volunteers were asked about their experiences, some reported being able to remember the pre-dream instructions they had received and attempted to carry them out. Some also reported hearing the questions they got while in the dream, though not always in the same ways. Some reported hearing words that clearly felt like they were coming from outside their current reality, while others said it felt like they were hearing them through a radio or another form of communication within the dream. But there were still times when people couldn’t clearly recall what had happened or when the questions they said they received in the dream didn’t match the questions they had actually gotten.
Tantalizing as the study’s findings are, they are based on a small sample size, so any conclusions should be viewed with some added caution. But they do demonstrate that it’s at least possible to have two-way communication with dreamers, Paller said. And the fact that different groups of scientists, in different parts of the world and using slightly different methods, were all able to record this happening indicates that it’s not just some isolated or misidentified phenomenon, he added.
The team has coined the phenomenon “interactive dreaming.” And now that they feel they’ve shown it’s possible, they plan to continue improving people’s ability to enter that state.
“We are currently exploring possibilities for running experiences in people’s own homes instead of in the sleep laboratory. There may be some advantages to doing so, as people will not be influenced by the unusual environment of a sleep laboratory or the monitoring technology we use,” Paller said. One avenue they’re exploring for future research is using a smartphone app that teaches people how to lucid dream and how to get better at it—an app that’s already available, for any curious onlookers out there.
The hope is that this technique will allow researchers like Paller to get a bit closer to cracking the mysteries of our dream lives and how they might affect our waking hours. In time, this research might even be applied proactively to improve people’s lives through improving their sleeping and dreaming habits.
“The applications could be developed for problem solving, practicing well-honed skills, spiritual development, nightmare therapy, and strategies for other psychological benefits,” Paller said.