If you've encountered a sleep walker, you probably understand that some communication with a dreamer is possible. But a new study, encompassing four independent experiments, reveals lucid dreamers can not only communicate with the outside world while snoozing but also answer yes-or-no questions and simple math problems. This is based on studies of 36 volunteers in the US, France, Germany, and the Netherlands, reports Gizmodo. Some considered themselves to be lucid dreamers—people who are aware they are dreaming—while others didn't. Either way, experts tried to train the dreamers to become lucid in response to external stimuli, like flashing lights or spoken word. In 15 of 57 sleep sessions (26%), participants signaled to researchers that they'd entered a lucid dream using previously agreed upon eye or facial movements.
In half of those sessions, a participant correctly answered at least one question, using the eye or facial movements. In 158 attempts to communicate, researchers received 29 correct answers, for a rate of 18%, per CNN. "Our results showed that dreamers could comprehend questions correctly, hold information in working memory and manipulate information (as in math computations), and express their answers coherently," says Ken Paller, a neuroscientist at Northwestern. A University of Wisconsin researcher not involved with the study tells Science that the work "challenges the foundational definitions of sleep." PBS' Nova has a video on the experiment here. Paller tells Gizmodo that "interactive dreaming" could have benefits "for problem solving, practicing well-honed skills, spiritual development, [and] nightmare therapy." And there's an app for that. (Read more dreams stories.)