Nightmares are defined as repeated occurrences of extremely dysphoric and well-remembered dreams that usually involve subjective threats to survival, security, or physical integrity. Generally, they occur during rapid eye movement sleep (REMS) and lead to awakenings with distress and insufficient overnight sleep. Nightmares may occur spontaneously (idiopathic) or as recurrent nightmares. Recurrent nightmares cause significant distress and impairment in occupational and social functioning, as have been commonly observed in post-traumatic stress disorder, depression and anxiety. By contrast, during lucid dreaming (LD), subjects get insight they are dreaming and may even control the content of their dreams. These features may open a way to help those who suffer from nightmare disorder through re-significations of the dream scene, i.e., knowing that they are dreaming and having control over their dream content. Thus, lucid dreamers might be able to render nightmares normal dreams, thereby assuring a restoring sleep. The aim of the present study is to review the existing literature of the use of LD as an auxiliary tool for treatment of nightmares. We conducted a careful literature search for eligible studies on the use of LD treatment for nightmares. We observed that whereas LD may be a feasible aid in the treatment of patients with nightmares through minimizing their frequency, intensity and psychological distress, the available literature is still scarce and does not provide consistent results. We conclude therefore that more research is clearly warranted for a better estimation of the effective conductance and therapeutic outcome of LD treatment in clinical practice.

The first philosopher who referred to lucid dreaming (LD) was Aristotle, who pointed out that something in the dreamers' consciousness tells them they are dreaming. In the Middle Ages, Aquinas commented that while asleep a man may judge that what he sees is a dream. During enlightenment, Reid alleged that he experienced waking-like cognition during dreams. In the 19th century, Nietzsche mentioned that he sometimes would realize he was dreaming amid a nightmare. In the past century, new arguments were given against the arising of self-consciousness in dreams. Malcolm, for example, based on the incapacity of communicating with the external world during the dream, concluded for the impossibility of a genuine dream "experience"which would preclude LD. In the 1970s, there was a brief discussion between Dennett, for whom dreams are not experiences, and Emmett, who rebutted his argument citing LD, followed by Dennett's reply that LDs are merely "illusions of a dream within a dream." In 1981, the psychophysiologist LaBerge and coworkers recorded LD in the laboratory, which proved scientifically the existence of LD. Nowadays, many philosophers consider dreams as a key phenomenon for the study of consciousness and the mind-body problem, such as Antti Revonsuo, Jennifer Windt, Evan Thompson, and Thomas Metzinger, who agree that LD presents cognitive functions like self-consciousness. In this review, we explore these and other Western thinkers who wrote about LD throughout history.