Dreams are involuntary sequences of images, ideas, emotions, and sensations that typically occur during specific sleep stages. People dream for approximately two hours each night, with individual dreams lasting between 5 and 20 minutes. Dreamers may, however, experience them as considerably longer. The exact reason for dreaming is still largely a mystery, with several theories proposing various functions ranging from emotional regulation to memory processing.
Starting around 1904, Salvador Dali, a renowned surrealist painter, began to draw inspiration from dreams in his artistic work.
Henri Rousseau, a prominent painter, depicted dreams in his artwork around 1910.
A pivotal moment in dream research occurred in 1953 with the publication of a paper by Aserinsky and Kleitman, which identified REM sleep as a distinct sleep stage and connected it to dreaming.
Melatonin, a hormone linked to sleep and later discovered to influence dream vividness, was chemically isolated in 1958.
In 1966, Calvin S. Hall and Robert Van de Castle published "The Content Analysis of Dreams," introducing a coding system for dream analysis and revealing cross-cultural similarities in dream content.
Published in 1971, "The Lathe of Heaven" explored the narrative device of dreams becoming reality in speculative fiction.
Pablo Picasso, a highly influential artist, incorporated dream themes into his artistic creations up to 1973.
On April 12, 1975, psychologist Keith Hearne achieved a breakthrough by successfully recording a communication from a dreamer during a lucid dream.
Hobson and McCarley proposed the activation-synthesis hypothesis in 1977, suggesting that dreams play a functional role in the learning process.
In 1983, Crick and Mitchison proposed the "reverse learning" theory, suggesting that dreams function as a cleaning-up operation in the mind, removing unnecessary information during sleep.
The year 1984 saw the emergence of films like "Dreamscape" and the "Nightmare on Elm Street" series, exploring themes of dream manipulation and blurred boundaries between dreams and reality in speculative fiction.
In 1985, Calvin S. Hall's extensive collection of dream reports, amassed over decades, was made publicly available by his protégé William Domhoff.
Salvador Dali, the celebrated surrealist, persistently integrated dream imagery into his artistic endeavors until 1989.
In 1995, Hartmann proposed that dreams serve a "quasi-therapeutic" function, allowing individuals to process trauma in a safe environment.
In 2000, Mark Solms published a paper demonstrating that REM sleep and dream phenomena are separable, challenging the previously established strong link between the two.
Revonsuo introduced the threat simulation hypothesis in 2000, proposing that dreams evolved as a mechanism for practicing responses to threats for survival.
A 2010 Harvard study provided experimental evidence supporting the correlation between dreams and improved learning.
The film "Inception," released in 2010, further explored the concept of dream manipulation within the realm of speculative fiction.
Revonsuo proposed the social simulation theory in 2015, suggesting that dreams function as simulations for training social skills and bonds.
In 2021, Eagleman and Vaughn presented the defensive activation theory, positing that dreams serve to protect the brain's visual cortex from being taken over by other senses during sleep.