Lucid dreaming—dreaming while aware that one is dreaming—was verified in five selected subjects who signaled that they knew they were dreaming while continuing to dream during unambiguous REM sleep. The signals were specific dream actions with observable physical counterparts, performed according to pre-sleep agreement. This signaling ability allows proficient lucid dreamers to conduct dream experiments, marking the exact timing of dream events to enable precise psychophysiological correlations and systematic hypothesis testing.
Over three years, a single subject (the author) learned to have lucid dreams—dreams in which the dreamer knows they are dreaming. Without any technique, fewer than one lucid dream occurred per month. Auto-suggestion produced 1 to 13 lucid dreams per month (average 5.4), with at most two per night. A mnemonic technique called MILD yielded 18 to 26 lucid dreams per month (average 21.5), with up to four per night, demonstrating that lucid dreaming can be deliberately induced.