Short answers, pulled from the story.
In Old English, the word dream described noise, joy, or music rather than sleep narratives. This linguistic shift occurred in the thirteenth century when the term began to describe the series of thoughts and images occurring during sleep. The transformation was likely influenced by the Old Norse word draumr.
The discovery of REM sleep occurred in 1953 by Aserinsky and Kleitman. This discovery marked a turning point by linking dreams to a distinct phase of sleep. Despite this finding, many studies purporting to uncover the function of dreams were actually studying REM sleep rather than the dream phenomena itself.
Modern theories include the activation-synthesis hypothesis proposed by Hobson and McCarley in 1977 and the reverse learning theory offered by Crick and Mitchison in 1983. Hartmann proposed a quasi-therapeutic function in 1995, while Revonsuo introduced the threat simulation hypothesis in 2000. More recently, Eagleman and Vaughn proposed a defensive activation theory in 2021.
Ancient Hebrews believed dreams were the voice of one God alone and differentiated between good dreams from God and bad dreams from evil spirits. In Islam, dream interpretation is the only way that Muslims can receive revelations from God since the death of the last prophet Muhammad. The Somniale Danielis attempted to teach Christian populations to interpret their dreams.
Adults report remembering around two dreams per week on average. Dream content that is novel, intense, or unusual is more easily remembered according to the salience hypothesis. People who score high on measures of personality traits associated with creativity, imagination, and fantasy tend to show more frequent dream recall.
The first successful recording of communication from a dreamer occurred on the 12th of April 1975. Psychologist Keith Hearne recorded a subject who agreed to move his eyes left and right upon becoming lucid. This event scientifically verified the occurrence of lucid dreaming.