Lucid Dreaming (LD) is defined as the phenomenon of becoming consciously aware of dreaming while still dreaming. In sleep laboratory experiments LD has been verified to occur during REM sleep stage by proficient lucid dreamers who have signaled while becoming lucid through specific pre-determined eye-movements. Using this method, (lucid) dreamed activity has been shown to correlate with both psychophysiological and neurophysiological responses to those observable if the same activity was to be performed during wakefulness. LD has also shown potential to be of therapeutic value, in reducing recurrent nightmare frequency. Recurrent nightmare sufferers engaging in Lucid Dreaming Treatment (LDT) show reduced nightmare frequency after treatment. As such, LDT has been suggested to be effective in the treatment of posttraumatic nightmares in Posttraumatic Stress Disorder (PTSD). The attitude and feeling of control provided by LDT has been shown to be fruitful also in fearful waking situations, indicating that LDT might be effective in disorders epitomized by fear.