Dreams have fascinated mankind for thousands of years. In much of our ancient history dreams were seen as messages from gods, from the dead or some other form of higher spiritual realm.
Texts from ancient Egypt, Greece, Mesopotamia, China, and India, not to mention almost every major world religion have prophets, oracles and mystics who receive divine visitors and wisdom in their dreams.
Philosophers have debated the purpose and meaning of dreams from antiquity through to the modern day, but it is only in the last one hundred years that dreams been subjected to empirical research and the theories have been based on scientific study.
The question of whether dreams actually have a physiological, biological or psychological function has yet to be conclusively answered. Many theories have been proposed to answer the questions; Why do we dream? or What purpose do dreams serve? However none of these have been proven, and there is much debate between the supporters of different theories.
The ‘when’ of dreaming is at least now well understood, most of our dreams occur during the REM phase of our sleep cycle, and on an average night you have anywhere between three and seven dreams, at a rate of around one dream every 90 minutes (one per sleep cycle).
One of the troubles in answering the question ‘Why do we dream?’ is we actually use the term ‘dream’ to cover quite a wide variety of experiences, basically anything that happens while we asleep, from a few vague, confusing thoughts that last little more than a few seconds, right through to incredibly vivid, emotional, intense sensory experiences that last up to half an hour.
It is entirely possible that no one theory of dreaming is correct, and the truth is some combination of ideas. Below I have grouped many of the idea around the purpose and meaning of dreaming into four broad categories.
Psychoanalytic Theory of Dreams
One of the first modern theories of dreaming came from the Freud and Jung in the then emerging field of psychoanalysis. In 1900, Sigmund Freud published his book The Interpretation of Dreams, where he put forward the view that dream were the fulfilment of an individual’s unconscious desires. Guided by the idea that human beings were primarily driven by sexual and aggressive instincts, he believed these repressed thoughts, which were unable to surface during our conscious waking state manifested themselves through the content of our dreams.
Carl Jung also believed dreams were a representation of a person’s unconscious, however rather than viewing this as an animalistic facet of individuality he saw it more as a spiritual aspect, and as such dreams were a window into this deeper nature.
Jung thought dreams could be used as a guide, a method of communication, to bring the conscious and unconscious minds into harmony.
Psychoanalytic theories of dreaming, essentially suggest dreams are like a kind of therapy, that by observing them we can learn more about ourselves and the nature of our unconscious mind.
Dreams to Process Experiences and Encode Memories
In a typical waking day your brain has to process millions of pieces of sensory information, but not everything we experience is actually useful, imagine if you remembered the make of every car that drove past you, or what clothes every person you had ever met in your life had been wearing, the sheer volume of information would be too much for us to function normally. So while asleep, the brain sorts through every sight, sound, thought, feeling, and decision from the day to determine what information needs to be kept , and what can be forgotten.
While the neurons in your brain are firing away, transforming this vast pool of information into long term memories, the content being processed shows up as dreams. There is some evidence to support this idea; in one study people who were actively learning new skills such taking a course in a foreign language, showed more dream activity than those who were not. Another study from MITs Center for Learning and Memory, looking at neural patterns in rats, found that exactly the same patterns showed up in their dreams as when they were at crucial decision points when running mazes during the day.
These and similar studies suggest that the very least, dreams play a crucial role in our formation of memories.
Dreaming to Prepare for Life’s Challenges
Another reason for dreams could be as an evolutionary mechanism to allow us to prepare for life threatening ‘fight of flight’ type situations in the real world by letting us rehearse them and try out different options while in a safe environment. Think how often your dreams contain highly charged, dangerous, or adrenaline filled situations, probably far more than these type of events ever occur in real life.
This idea is backed up by the work of Antti Revonsuo, , who showed that the regions of the brain responsible for both our ‘fight of flight’ response and for motor activity are more active than normal while during REM sleep
This theory has more recently been extended to preparing for not just physical threats but also challenging emotional situations. Since studies have shown the brain treats physical and emotional pain in the same way, this makes sense.
Our ancient ancestors might have spent their day afraid of being attacked by a lion, and so dreamt of ways to avoid this painful situation, but if we are more likely to spend our day preoccupied with the fear of social rejection from embarrassing ourselves, our brain will dream scenarios to prepare for and avoid this pain.
Dreaming for Creativity and Problem Solving
In the dream state, the critical judging part of our conscious mind is supressed, and so we are more likely to entertain ideas that would be instantly dismissed while awake. This allows us to be much more creative and come up with more novel solutions to problems than we would do otherwise.
It is possible this is the function of dreams, to allow a kind of natural selection of ideas. Whether led by recent activity when awake or entirely randomly, neural circuitry responsible for sensations, memories and emotions is activated. These signals are then spontaneously recombined and linked together into different ideas and concepts. Most of these new combinations won’t make any sense and so aren’t useful, but by pure chance some of the random configurations will be a useful solution, idea or insight.
This idea, that dreams results from the brains attempts to make sense of and order its own random internal activity is supported by Hobson and McClarley in their Activation-Synthesis Model of Dreaming. They published many studies on this idea between 1977 and 1999.
Other Theories of Dreaming
Here a few more theories of why we dream that deserve a quick mention, but which don’t really fit into any of the groups above.
One idea put forward by Antrobus in his 1993 paper, Characterises of dreams, says dreams may be the result of our brains trying to interpret external sounds and stimuli we can still hear and feel while asleep.
Alternatively it is possible dreams developed from a forgotten evolutionary defence mechanism, still used by many animals where they ‘play dead’ known as tonic immobility. This keeps the brain active while essentially shutting down all of the bodies physical systems to fool predators.
And finally there are some researchers who believe dreams have no meaning or purpose at all and are nothing more than random electrical impulses generated in the brain.