A lucid dream is a type of dream in which the dreamer becomes aware that they are dreaming while dreaming. During a lucid dream, the dreamer may gain some amount of control over the dream characters, narrative, or environment. Lucid dreaming has been studied and reported for many years. Prominent figures from ancient to modern times have been fascinated by lucid dreams and have sought ways to better understand their causes and purpose.

Many different theories have emerged as a result of scientific research on the subject and have even been shown in pop culture. Further developments in psychological research have pointed to ways in which this form of dreaming may be utilized as a form of sleep therapy.