Why do we dream?
Like memories and fantasies, dreams are imagery in the absence of external simulation and can seem real. Some may be pleasant and some may be terrible. Our dream theater is quite flexible. We may dream in full color or in black and white.
But why do we dream? Here are some of the theories on why we have these dreams.
Dreams as "the Residue of the Day"
You may recall dreams involving fantastic adventures, but most dreams involve memories of the activities and problems of the day (Morewedge & Norton, 2009). If we are preoccupied with illness or death, sexual or aggressive urges, or moral dilemmas, we are likely to dream about them. The characters in our dreams are more likely to be friends and neighbors than spies, monsters, and princes - subjects that have been referred to, poetically, as "the residue of the day."
Traumatic events, however, can spawn nightmares. People who have frequent nightmares are more likely than others to also suffer from anxiety, depression, and other psychological problems (Roberts et al., 2009)
Dreams as the Expression of Unconscious Desires
In the Disney film Cinderella, a song lyrics goes, "A dream is a wish your heart makes." Sigmund Freud theorized that dreams reflect unconscious wishes and urges. He argued that dreams express impulses we would censor during the day, although researchers find no evidence for this assertion. Moreover, he said that the content of dreams is symbolic of unconscious fantasized objects. In his method of psychoanalysis, Freud would interpret his clients' dreams.
The Activation-Synthesis Model of Dreams
There are also biological views of the "meanings" of dreams. According to the activation-synthesis model, acetylcholine (a neurotransmitter) and the pons in the brain, stimulate responses that lead to dreaming (Hobson, 2003, 2009; Stuart & Conduit, 2009). One is activation of the reticular formation, which arouses us, but not to waking. During the waking state, firing of these cells is linked to movement, particularly the movements in walking, running, and other physical acts. But during the fifth stage (REM) of sleep, neurotransmitters tend to inhibit activity so we usually do not thrash about as we dream (Stuart & Conduit, 2009). But the eye muscles are stimulated and show the REM activity associated with dreaming. The reticular formation also stimulates parts of the cortex involved in memory. The cortex the synthesizes, or puts together, these sources of stimulation to yield the stuff of dreams. Yet research with PET scan shows that the frontal lobes of the brain, which seem to be where we make sense of experience, are relatively inactive during sleep (Wade, 1998). Dreams are therfore more likely to be emotionally gripping than coherent in plot.
Because recent events are most likely to be reverberating in our brains, we are most likely to dream about them. With the brain cut off from the world outside, learning experiences and memories are replayed and consolidated during sleep (Siegel, 2009). It's useful to get a night of sleep between studying and test-taking, if you can.
Although these studies are psychologically or biologically based, no one knows the exact reason why we dream. But all we know is that dreams are natural recurrences in our lives.
Psychology, Third Edition
Spencer A. Rathus