LUCID DREAM definition: 1. a dream in which the person who is dreaming is asleep but aware that they are dreaming, and is…. Learn more. Lucid dreams occur when you are aware of dreaming while asleep, allowing control over dream events. Lucid dreams primarily happen during REM sleep, with potential benefits including reduced anxiety and enhanced problem-solving skills. In the psychology subfield of oneirology, a lucid dream is a type of dream wherein the dreamer realizes that they are dreaming during their dream. If you have a lucid dream, you're asleep but aware that you're dreaming. Researchers don't understand the cause of these vivid dreams but are trying to learn more.