A phone app that has users listen to a specific sound before bed and practice associating it with their awareness of their thoughts and body can increase the chances of having lucid dreams. The app plays the sound again six hours later to reactivate self-awareness in the sleeping user, coaxing them to become lucid mid-dream. A rough approximation of the technique using an app can promote lucid dreaming at home, researchers report in the October Consciousness and Cognition. In one experiment, 19 people who used the app every night for a week reported an average of 2.11 lucid dreams, which is a big increase for lucid dreaming. In another experiment, only 5 percent of people who heard the sounds from training kept up that rate of lucid dreaming, hinting that the real sound cues were indeed behind the app’s effectiveness.