Lucid dreaming has been researched scientifically, and its existence is well established.
A lucid dream is any dream in which one is aware that one is dreaming. The term was coined by the Dutch psychiatrist and writer Frederik (Willem) van Eeden (1860–1932).In a lucid dream, the dreamer may be able to exert some degree of control over their participation within the dream or be able to manipulate their imaginary experiences in the dream environment. Lucid dreams can be realistic and vivid. It is shown that there are higher amounts of beta-1 frequency band (13–19 Hz) experienced by lucid dreamers, hence there is an increased amount of activity in the parietal lobes making lucid dreaming a conscious process.
Wikipedia states that a dream journal (or dream diary) is a journal in which dream experiences are recorded. A dream journal might include a record of nightly dreams, personal reflections and waking dream experiences. It is often used in the study of dreams and psychology.
Dream journals are also used by people trying to lucid dream. They are also regarded as a useful catalyst for remembering dreams.
The use of a dream diary was recommended by Ann Faraday in The Dream Game as an aid to memory and a way to preserve details, many of which are otherwise rapidly forgotten no matter how memorable the dream originally seemed. The very act of recording a dream can have the effect of improving future dream recall. Keeping a dream journal conditions a person to view remembering dreams as important.
Traditionally, dreams have been recorded in a paper journal (as text, drawings, paintings, etc.) or via an audio recording device (as narrative, music or imitations of other auditory experiences from the dream.) Now with the internet, many sites offer the ability to create a digital dream journal.