The researchers analyzed brain signals and eye and facial movements from people involved in “conversations” about lucid dreams.
K. Konkoly
By Sofia Moutinho
In the movie BeginningLeonardo DiCaprio enters other people’s dreams to interact with them and steal secrets from his subconscious. Now, it seems that this sci-fi plot is a baby step closer to reality. For the first time, researchers have had “conversations” involving new questions and mathematical problems with lucid dreamers – people who are aware that they are dreaming. The findings, from four laboratories and 36 participants, suggest that people can receive and process complex external information while sleeping.
“This work challenges basic definitions of sleep,” says cognitive neuroscientist Benjamin Baird, of the University of Wisconsin, Madison, who studies sleep and dreams, but was not part of the study. Traditionally, he says, sleep is defined as a state in which the brain is disconnected and unconscious from the outside world.
Lucid dreaming was one of its first mentions in the writings of the Greek philosopher Aristotle in the fourth century BC, and scientists have observed it since the 1970s in experiments on the REM sleep phase, when most dreams occur. One in two people had at least one lucid dream, about 10% of people have them once a month or more. Although rare, this ability to recognize that you are in a dream – and even to control some aspects of it – can be enhanced with training. Some studies have attempted to communicate with lucid dreamers using stimuli such as lights, shocks and sounds to “enter” people’s dreams. But these recorded only minimal responses from the sleepers and did not involve a complex transmission of information.
Four independent teams in France, Germany, the Netherlands and the United States tried to go further and establish complex two-way communication during dreams, using speech and asking questions that sleepers never heard in their training. They recruited 36 volunteers, including some experienced lucid dreamers and others who have never had a lucid dream before, but remembered at least one dream a week.
The researchers first trained participants to recognize when they were dreaming, explaining how lucid dreams work and demonstrating clues – sounds, lights or finger taps – that they would present while dreamers slept. The idea was that these clues would signal to participants that they were dreaming.
The nap sessions were scheduled at different times: some at night, when people used to go to bed, and others in the early morning. Each laboratory used a different way to communicate with the sleeper, from spoken questions to flashing lights. Sleepers were instructed to signal that they had entered a lucid dream and to answer questions by moving their eyes and faces in specific ways – for example, by moving their eyes three times to the left.
While participants fell asleep, the scientists monitored their brain activity, eye movements and facial muscle contractions – common REM sleep indicators – with electroencephalogram helmets equipped with electrodes. Of a total of 57 sleep sessions, six individuals indicated that they were having lucid dreams in 15 of them. In these tests, the researchers asked dreamers simple questions, yes or no, or math problems, like eight minus six. To answer, dreamers used the signals they learned before falling asleep, which included smiling or frowning, moving their eyes several times to indicate a sum, or, in the German laboratory, moving their eyes in patterns that corresponded to Morse code.
Researchers asked 158 questions to lucid dreamers, who answered correctly 18.6% of the time, the researchers report today. Current Biology. Dreamers gave the wrong answer to just 3.2% of the questions; 17.7% of the answers were not clear and 60.8% of the questions did not get an answer. The researchers say that these figures show that communication, even if difficult, is possible. “It’s a proof of concept,” says Baird. “And the fact that different labs have used all these different ways to prove that it is possible to have this kind of two-way communication … makes it stronger.”
After several questions, the dreamers were awakened and asked to describe their dreams. Some remembered the questions as part of a dream: A dreamer reported math problems when listening to a car radio. Another was at a party when he heard the researcher interrupt his dream, like the narrator of a film, to ask if he spoke Spanish.
The experiment offers a better way to study dreams, says lead author Karen Konkoly, a cognitive neuroscientist at Northwestern University. “Almost everything that is known about dreams is based on retrospective reports provided when the person is awake and can be distorted.” Konkoly hopes that this technique can be used in the future therapeutically to influence people’s dreams so that they can better deal with trauma, anxiety and depression.
“Conversations” while sleeping can also help the dreamer solve problems, learn new skills or even come up with creative ideas, says Baird. “The dream is a highly associative state that can have advantages when it comes to creativity.”
Cognitive neuroscientist Michelle Carr of the University of Rochester, who was not involved in the study, says she is excited about these future applications. But she emphasizes that retrospective dream reports cannot be replaced. “When you’re in a dream, your reporting skills are very limited,” she says.
Changing people’s thinking during dreams is still science fiction, highlights Northwestern co-author and cognitive neuroscientist Ken Paller. However, he thinks the experiment is an important first step in communicating with dreamers; he likens it to the first phone conversation or talking to an astronaut on another planet. Dreamers live in a “world entirely made up of memories stored in the brain,” he says. Now, the researchers seem to have found a way to communicate with the people of this world.