Y.D. Tsai developed in 1995 a 3-hypothesis theory[65] that is claimed to provide a mechanism for mind-body interaction and explain many dream-related phenomena, including hypnosis, meridians in Chinese medicine, the increase in heart rate and breathing rate during REM sleep, that babies have longer REM sleep, lucid dreams, etc.
Dreams are a product of "dissociated imagination," which is dissociated from the conscious self and draws material from sensory memory for simulation, with feedback resulting in hallucination. By simulating the sensory signals to drive the autonomous nerves, dreams can affect mind-body interaction. In the brain and spine, the autonomous "repair nerves," which can expand the blood vessels, connect with compression and pain nerves. Repair nerves are grouped into many chains called meridians in Chinese medicine. When some repair nerves are prodded by compression or pain to send out their repair signals, a chain reaction spreads out to set other repair nerves in the same meridian into action. While dreaming, the body also employs the meridians to repair the body and help it grow and develop by simulating very intensive movement-compression signals to expand the blood vessels when the level of growth enzymes increase.
Other hypotheses on dreaming
There are many other hypotheses about the function of dreams, including:[66]
Dreams allow the repressed parts of the mind to be satisfied through fantasy while keeping the conscious mind from thoughts that would suddenly cause one to awaken from shock.[67]
Freud suggested that bad dreams let the brain learn to gain control over emotions resulting from distressing experiences.[66]
Jung suggested that dreams may compensate for one-sided attitudes held in waking consciousness.[68]
Ferenczi[69] proposed that the dream, when told, may communicate something that is not being said outright.
Dreams regulate mood.[70]
Hartmann[71] says dreams may function like psychotherapy, by "making connections in a safe place" and allowing the dreamer to integrate thoughts that may be dissociated during waking life.
More recent research by psychologist Joe Griffin, following a twelve-year review of data from all major sleep laboratories, led to the formulation of the expectation fulfilment theory of dreaming, which suggests that dreaming metaphorically completes patterns of emotional expectation in the autonomic nervous system and lowers stress levels in mammals.[72][73]
Dream content
From the 1940s to 1985, Calvin S. Hall collected more than 50,000 dream reports at Western Reserve University. In 1966 Hall and Van De Castle published The Content Analysis of Dreams in which they outlined a coding system to study 1,000 dream reports from college students.[74] It was found that people all over the world dream of mostly the same things. Hall's complete dream reports became publicly available in the mid-1990s by Hall's protégé William Domhoff, allowing further different analysis. Personal experiences from the last day or week are frequently incorporated into dreams.[75]
Visuals
The visual nature of dreams is generally highly phantasmagoric; that is, different locations and objects continuously blend into each other. The visuals (including locations, characters/people, objects/artifacts) are generally reflective of a person's memories and experiences, but often take on highly exaggerated and bizarre forms.
Emotions
The most common emotion experienced in dreams is anxiety. Other emotions include abandonment, anger, fear, joy, happiness, etc. Negative emotions are much more common than positive ones.[74]
Sexual themes
The Hall data analysis shows that sexual dreams occur no more than 10% of the time and are more prevalent in young to mid-teens.[74] Another study showed that 8% of men's and women's dreams have sexual content.[76] In some cases, sexual dreams may result in orgasms or nocturnal emissions. These are colloquially known as wet dreams.[77]
Recurring dreams
While the content of most dreams is dreamt only once, many people experience recurring dreams—that is, the same dream narrative or dreamscape is experienced over different occasions of sleep.