People who are asleep and having a lucid dream—aware that they are dreaming—can perceive questions from an experimenter and answer them in real time using eye movements and facial muscle contractions. In a study of 36 individuals during REM sleep, including frequent lucid dreamers, a novice, and a patient with narcolepsy, participants performed perceptual analysis of new information, held information in working memory, computed simple answers, and gave volitional replies. Correct answers occurred on 29 occasions across 6 individuals, documented by four independent laboratories. This two-way communication channel allows real-time interrogation of dream cognition and characteristics.
A smartphone-based procedure called Targeted Lucidity Reactivation (TLR) can increase lucid dreaming without requiring laboratory equipment. In two experiments, participants reported more lucid dreams when they received sounds during REM sleep that they had heard during pre-sleep training, compared to a prior week without TLR or to blinded control procedures on alternate nights. The findings indicate that the sounds strengthen a link formed during training between the cues and a mindset of carefully analyzing one's current experience, which carries into dreams and boosts lucidity.