According to a study posted on Brescia University's website, dreams are defined as a series of thoughts, visions or feelings, and arise several times per night during an average sleep cycle. Dr. Michael Bordieri, psychology professor at Murray State University, visits Sounds Good to discuss the psychology of dreams with Tracy Ross.
Sleep isn't only crucial in combatting drowsiness or crankiness -- a full sleep cycle, containing five different stages, bolsters the immune system, builds muscle and bone, mends and regenerates tissues, and consolidates memories and new information. These stages are differentiated by NREM (non-rapid eye movement) and REM (rapid eye movement), the latter being the stage during which dreams occur. Dreams have been a point of interest in religion, science, and general sociology for hundreds of years. With something as elusive as dreams, however, they've been prone to several different analyses and interpretations.
Sigmund Freud, for example, proposed the idea that dreams were often forms of wish-fullfilment. Freud's contemporary, Carl Jung, believed that dreams were presented in their own specific "language" of symbols and metaphors, unlike the languages spoken while awake, that expressed an individual's unconscious state. Other theories vary still, such as Finnish psychologist Antti Revonsuo, who suggested that dreams occuring during the REM cycle activate the fight-or-flight section of the brain, similarly to the way it activates during a survival threat. According to Revonsuo, the primary function of negative dreams is for the brain to rehearse for similar real events, so that threat recognition and avoidance happens more automatically.
Michael Bordieri visits Sounds Good to discuss some of these theories, as well as various experiments conducted to explore dreams and their affect on the brain, including the affect of one's external environment on the unconscious mind.