There is a branch of science called oneirology which studies dreams. This discipline combines features of neuroscience, psychology, and even literature, but does not provide the answer to an important question: why do people have dreams? There is no clear answer to this puzzle yet, but there are some interesting hypotheses, some of which are presented here.
1. Hidden desires – Sigmund Freud
One of the first few scholars, who began to study dreams, was the founder of psychoanalysis, Sigmund Freud. After analyzing dreams of hundreds of his patients, Freud developed a theory which is still supported by some of his followers: dreaming represents suppressed desires and hidden inclinations of people.
According to Freud, while dreaming, people see what they want to achieve, literally or symbolically. For example, if someone had a dream that his mother had died, this does not mean that this person subconsciously wants to kill her, instead, according to the Freudian interpretation, there is a certain conflict between the mother and the son, and the problem has a simple and effective solution, but the mother does not know about it. Thus, the death of the mother in a dream is an indirect symbol of resolving this conflict.
By studying dreams, the founder of the psychoanalytic method helped his patients to extract their deeply hidden fears and desires which these people did not know existed in their subconscious mind.
2. A side effect of electrical activity of the brain – Alan Hobson
Freud’s theory suggests rethinking of peoples’ experiences in their dreams. But psychiatrist Allan Hobson, the author of another popular theory to explain the occurrence of dreams, argues that dreams do not carry any subconscious meanings, they are simply a result of random electrical impulses that occur in regions of the brain responsible for emotions, perceptions and memories.
Hobson referred to his theory as “Operationally-synthetic model,” according to which, the brain is simply trying to interpret random signals, resulting in generation of colorful or not so vivid visions.
“Operationally-synthetic model” may also help in explaining why some people tend to create fictional works of literature, which are essentially nothing more than a kind of “waking dreams”, created by the interpretation of the signals received by the limbic system of the brain from the outside world.
3. Sending short-term memories to long-term storage – Zhang Jie
Perhaps dreams are indeed the result of random nerve impulses, but what if these impulses are not random at all? This idea was suggested by psychiatrist Zhang Jie, who called it a “Theory of constant activation.” Zhang Jie believes that the brain constantly processes many memories, regardless of whether the person is asleep or awake. When short-term memories are transferred to long-term storage in the compartments of long-term memory, dreams are created.
4. Getting rid of useless rubbish
The so-called “Reverse learning theory” states that dreams help people to get rid of some unwanted associations and relationships that are formed in the brain throughout the day. We can say that dreams serve as a means of “garbage collection”, clearing the mind of unwanted and useless memories. This allows prevent an overload due to large amount of information, which inevitably enters our brain every day.
This hypothesis is directly opposite to the “theory of reverse learning”. According to this theory, dreams are part of the process for organizing and storing information.
Several studies support this idea by presenting their findings to show that people better remember information received just before they go to sleep. Just like Zhang Jie and her “Theory of constant activation”, the apologists of this hypothesis believe that dreams help us understand and organize information which we process throughout the day.
Another supporting fact for this hypothesis was brought about by recent studies in which it was found that if a person falls asleep soon after something bad or negative has happened, after waking up, everything will be remembered in detail, as if it happened a few minutes ago. Therefore, if there is a possibility of psychological trauma, it is best not to allow the victim go to sleep for as long it can possible be, the absence of dreams will help erase unpleasant experiences from memory.
6. Modified instinct for self-preservation inherited from animals
Some researchers have conducted studies which find apparent similarity between the behavior of animals which pretend to be “dead” in order to survive and the experience of humans when they have dreams.
During the time of “dream watching”, the brain works the same way as in the waking state, except there no signs of motor activity of the body. In this case, the same state occurs in animals when they pretend to be a corpse in order for the predator to stay away from them. Therefore, it is possible that this ability of humans to dream was inherited from the distant animal ancestors after undergoing some changes during evolution, because modern humans do not need to mimic the dead-like state.
7. Preparation for possible threats – Antti Revonsuo
The theory of self-defense instinct perfectly fits with the idea of the famous Finnish philosopher and neuroscientist Antti Revonsuo. He suggested that the biological function of dreams is to simulate various dangerous situations to practice and “rehearse” the reaction of the body to these threats. Individuals, who often encounter threats or danger in their dreams, in the event of a real danger will be more confident and prepared, because the situation is already “familiar” to them. Such training, according to Revonsuo, benefits the survival of a particular human individual and the human species overall.
This hypothesis, however, has one major drawback as it does not explain why some people experience positive dreams, which do not contain any threat or warning.
8. Solving the problem – Deirdre Barrett
This hypothesis, developed by the professor of psychology at Harvard University, Deirdre Barrett, is similar to the idea suggested by the Finnish scholar Antti Revonsuo.
Professor Barrett believes that dreams serve as some kind of a theater stage, where we can find answers to a lot of questions and come up with solutions to some problems. The brain works more effectively during sleeping because it can form new associations much quicker. Deirdre makes this conclusion based on her research, which has found that if a person is faced with a task before going to bed, after waking up, the task will be solved faster compared to people who were simply asked to solve the task, without a possibility to “look up” the answer in their dream.
9. The theory of natural selection for thoughts – Mark Blechner
The idea of solving problems through dreams is similar to the so-called theory of natural selection for thoughts developed by psychologist Mark Blechnerom. Here is how he describes dreaming:
“Dreaming is a stream of random images, some of which the brain selects and saves to use in the future. Dreams are composed of many variants of feelings, emotions, thoughts, and some other higher mental functions, some of which undergo some kind of natural selection and are deposited in the memory.”
Psychologist Richard Coates, in turn, is convinced that during sleep, the brain simulates various situations to choose the most appropriate emotional responses. That’s why in the morning, people usually do not worry about the anxiety and horror stories experienced in a dream, the brain makes it clear that this way it is just a “rehearsal”.
10. Alleviating negative feelings through symbolic associations – Ernest Hartmann
Proponents of this theory believe that dreaming is not a stream of random images or simulation of various emotional reactions, but rather a therapy session.
One of the founders of the so-called Modern theory of dreams, a psychiatrist and researcher of the nature of dreams Ernest Hartmann writes:
“If a person has a prevailing and vivid emotion, this person’s dreams are simple, if not primitive. For example, some survivors of psychological trauma often recall dreaming about something like: “I was lying on the beach, and suddenly a huge wave washed me away”. This is a fairly common event when an individual does not dream about a specific event, but some homogenous emotion, such as fear. If a person who falls asleep is perturbed by several things at once, dreams would have a more complex structure. The higher the emotional state of a particular person, the brighter the experienced dreams will become”.
Hartmann believes that dreams are an evolutionary mechanism by which the brain counterbalances negative effects of psychological trauma, presenting them to the person during dreaming in the form of symbols and associative images.