They are an enduring source of mystery for scientists and psychological doctors. Why do dreams occur? What causes them? Can we control them? What do they mean?
This article will explore the current theories, causes, and applications of dreaming.
- We may not remember dreaming, but everyone is thought to dream between 3 and 6 times per night
- It is thought that each dream lasts between 5 to 20 minutes.
- Around 95 percent of dreams are forgotten by the time a person gets out of bed.
- Dreaming can help you learn and develop long-term memories.
- Blind people dream more with other sensory components compared with sighted people.
Dreams: Do they represent our unconsious desires?
There are several theories about why we dream. Are dreams merely part of the sleep cycle, or do they serve some other purpose?
Possible explanations include:
- representing unconscious desires and wishes
- interpreting random signals from the brain and body during sleep
- consolidating and processing information gathered during the day
- working as a form of psychotherapy
From evidence and new research methodologies, researchers have speculated that dreaming serves the following functions:
- offline memory reprocessing, in which the brain consolidates learning and memory tasks and supports and records waking consciousness
- preparing for possible future threats
- cognitive simulation of real life experiences, as dreaming is a subsystem of the waking default network, the part of the mind active during daydreaming
- helping develop cognitive capabilities
- reflecting unconscious mental function in a psychoanalytic way
- a unique state of consciousness that incorporates experience of the present, processing of the past, and preparation for the future
- a psychological space where overwhelming, contradictory, or highly complex notions can be brought together by the dreaming ego, notions that would be unsettling while awake, serving the need for psychological balance and equilibrium
Much that remains unknown about dreams. They are by nature difficult to study in a laboratory, but technology and new research techniques may help improve our understanding of dreams.
Phases of sleep
Dreams most likely happen during REM sleep.
There are five phases of sleep in a sleep cycle:
Stage 1: Light sleep, slow eye movement, and reduced muscle activity. This stage forms 4 to 5 percent of total sleep.
Stage 2: Eye movement stops and brain waves become slower, with occasional bursts of rapid waves called sleep spindles. This stage forms 45 to 55 percent of total sleep.
Stage 3: Extremely slow brain waves called delta waves begin to appear, interspersed with smaller, faster waves. This accounts for 4 to 6 percent of total sleep.
Stage 4: The brain produces delta waves almost exclusively. It is difficult to wake someone during stages 3 and 4, which together are called "deep sleep." There is no eye movement or muscle activity. People awakened while in deep sleep do not adjust immediately and often feel disoriented for several minutes after waking up. This forms 12 to 15 percent of total sleep.
Stage 5: This stage is known as rapid eye movement (REM). Breathing becomes more rapid, irregular, and shallow, eyes jerk rapidly in various directions, and limb muscles become temporarily paralyzed. Heart rate increases, blood pressure rises, and males develop penile erections. When people awaken during REM sleep, they often describe bizarre and illogical tales. These are dreams. This stage accounts for 20 to 25 percent of total sleep time.
What are dreams?
Dreams are a universal human experience that can be described as a state of consciousness characterized by sensory, cognitive and emotional occurrences during sleep.
The dreamer has reduced control over the content, visual images and activation of the memory.
There is no cognitive state that has been as extensively studied and yet as frequently misunderstood as dreaming.
There are significant differences between the neuroscientific and psychoanalytic approaches to dream analysis.
Neuroscientists are interested in the structures involved in dream production, dream organization, and narratability. However, psychoanalysis concentrates on the meaning of dreams and placing them in the context of relationships in the history of the dreamer.
Reports of dreams tend to be full of emotional and vivid experiences that contain themes, concerns, dream figures, and objects that correspond closely to waking life.
These elements create a novel "reality" out of seemingly nothing, producing an experience with a lifelike timeframe and connections.
Nightmares are distressing dreams that cause the dreamer to feel a number of disturbing emotions. Common reactions to a nightmare include fear and anxiety.
They can occur in both adults and children, and causes include:
- emotional difficulties
- use of certain medications or drugs
Lucid dreaming is the dreamer is aware that they are dreaming. They may have some control over their dream.
This measure of control can vary between lucid dreams. They often occur in the middle of a regular dream when the sleeping person realizes suddenly that they are dreaming.
Some people experience lucid dreaming at random, while others have reported being able to increase their capacity to control their dreams.
What goes through our minds just before we fall asleep could affect the content of our dreams.
For example, during exam time, students may dream about course content. People in a relationship may dream of their partner. Web developers may see programming code.
These circumstantial observations suggest that elements from the everyday re-emerge in dream-like imagery during the transition from wakefulness to sleep.
Studies have examined the "characters" that appear in dream reports and how they the dreamer identifies them.
A study of 320 adult dream reports found:
- Forty-eight percent of characters represented a named person known to the dreamer.
- Thirty-five percent of characters were identified by their social role (for example, policeman) or relationship to dreamer (such as a friend).
- Sixteen percent were not recognized
Among named characters:
- Thirty-two percent were identified by appearance
- Twenty-one percent were identified by behavior
- Forty-five percent were identified by face
- Forty-four percent were identified by "just knowing"
Elements of bizarreness were reported in 14 percent of named and generic characters.
Another study investigated the relationship between dream emotion and dream character identification.
Affection and joy were commonly associated with known characters and were used to identify them even when these emotional attributes were inconsistent with those of the waking state.
The findings suggest that the dorsolateral prefrontal cortex, associated with short-term memory, is less active in the dreaming brain than during waking life, while the paleocortical and subcortical limbic areas are more active.
The concept of 'repression' dates back to Freud. Freud maintained that undesirable memories could become suppressed in the mind. Dreams ease repression by allowing these memories to be reinstated.
A study showed that sleep does not help people forget unwanted memories. Instead, REM sleep might even counteract the voluntary suppression of memories, making them more accessible for retrieval.
Two types of temporal effects characterize the incorporation of memories into dreams:
- the day-residue effect, involving immediate incorporations of events from the preceding day
- the dream-lag effect, involving incorporations delayed by about a week
The findings of one study suggest that:
- processing memories into dream incorporation takes a cycle of around 7 days
- these processes help further the functions of socio-emotional adaptation and memory consolidation
Dream-lag is when the images, experiences, or people that emerge in dreams are images, experiences, or people you have seen recently, perhaps the previous day or a week before.
The idea is that certain types of experiences take a week to become encoded into long-term memory, and some of the images from the consolidation process will appear in a dream.
Events experienced while awake are said to feature in 1 to 2 percent of dream reports, although 65 percent of dream reports reflect aspects of recent waking life experiences.
The dream-lag effect has been reported in dreams that occur at the REM stage but not those that occur at stage 2.
Memory types and dreaming
Two types of memory can form the basis of a dream.
- autobiographical memories, or long-lasting memories about the self
- episodic memories, which are memories about specific episodes or events
A study exploring different types of memory within dream content among 32 participants found the following:
- One dream (0.5 percent) contained an episodic memory.
- Most dreams in the study (80 percent) contained low to moderate incorporations of autobiographical memory features.
Researchers suggest that memories of personal experiences are experienced fragmentarily and selectively during dreaming. The purpose may be to integrate these memories into the long-lasting autobiographical memory.
A hypothesis stating that dreams reflect waking-life experiences is supported by studies investigating the dreams of psychiatric patients and patients with sleep disorders. In short, their daytime symptoms and problems are reflected in their dreams.
In 1900, Freud described a category of dreams known as "biographical dreams." These reflect the historical experience of being an infant without the typical defensive function. Many authors agree that some traumatic dreams perform a function of recovery.
One paper hypothesizes that the main aspect of traumatic dreams is to communicate an experience that the dreamer has in the dream but does not understand. This can help an individual reconstruct and come to terms with past trauma.
The themes of dreams can be linked to the suppression of unwanted thoughts and, as a result, an increased occurrence of that suppressed thought in dreams.
Fifteen good sleepers were asked to suppress an unwanted thought 5 minutes prior to sleep.
The results demonstrate that there were increased dreams about the unwanted thought and a tendency to have more distressing dreams. They also imply that thought suppression may lead to significantly increased mental disorder symptoms.
Research has indicated that external stimuli presented during sleep can affect the emotional content of dreams.
For example, the positively-toned stimulus of roses in one study yielded more positively themed dreams, whereas the negative stimulus of rotten eggs was followed by more negatively themed dreams.
Typical dreams are defined as dreams similar to those reported by a high percentage of dreamers.
Up to now, the frequencies of typical dream themes have been studied with questionnaires. These have indicated that a rank order of 55 typical dream themes has been stable over different sample populations.
Some themes are familiar to many people, such as flying, falling, and arriving late.
The 55 themes identified are:
- school, teachers, and studying
- being chased or pursued
- sexual experiences
- arriving too late
- a living person being dead
- a person now dead being alive
- flying or soaring through the air
- failing an examination
- being on the verge of falling
- being frozen with fright
- being physically attacked
- being nude
- eating delicious food
- being locked up
- insects or spiders
- being killed
- losing teeth
- being tied up, restrained, or unable to move
- being inappropriately dressed
- being a child again
- trying to complete a task successfully
- being unable to find toilet, or embarrassment about losing one
- discovering a new room at home
- having superior knowledge or mental ability
- losing control of a vehicle
- wild, violent beasts
- seeing a face very close to you
- having magical powers
- vividly sensing, but not necessarily seeing or hearing, a presence in the room
- finding money
- floods or tidal waves
- killing someone
- seeing yourself as dead
- being half-awake and paralyzed in bed
- people behaving in a menacing way
- seeing yourself in a mirror
- being a member of the opposite sex
- being smothered, unable to breathe
- encountering God in some form
- seeing a flying object crash
- seeing an angel
- part animal, part human creatures
- tornadoes or strong winds
- being at the movie
- seeing extra-terrestrials
- traveling to another planet
- being an animal
- seeing a UFO
- someone having an abortion
- being an object
Some dream themes appear to change over time.
For example, from 1956 to 2000, there was an increase in the percentage of people who reported flying in dreams. This could reflect the increase in air travel.
What do they mean?
Relationships: Some have hypothesized that one cluster of typical dreams, including being an object in danger, falling, or being chased, is related to interpersonal conflicts.
Sexual concepts: Another cluster that includes flying, sexual experiences, finding money, and eating delicious food is associated with libidinal and sexual motivations.
Fear of embarrassment: A third group, containing dreams that involve being nude, failing an examination, arriving too late, losing teeth, and being inappropriately dressed, is associated with social concerns and a fear of embarrassment.
Brain activity and dream types
In neuroimaging studies of brain activity during REM sleep, scientists found that the distribution of brain activity might also be linked to specific dream features.
Several bizarre features of normal dreams have similarities with well-known neuropsychological syndromes that occur after brain damage, such as delusional misidentifications for faces and places.
Dreams and the senses
This may suggest that the role of some cerebral structures, such as amygdala and hypothalamus, are involved in migraine mechanisms as well as in the biology of sleep and dreaming.
Music in dreams is rarely studied in scientific literature. However, in a study of 35 professional musicians and 30 non-musicians, the musicians experienced twice as many dreams featuring music, when compared with non-musicians.
Musical dream frequency was related to the age of commencement of musical instruction but not to the daily load of musical activity. Nearly half of the recalled music was non-standard, suggesting that original music can be created in dreams.
It has been shown that realistic, localized painful sensations can be experienced in dreams, either through direct incorporation or from memories of pain. However, the frequency of pain dreams in healthy subjects is low.
In one study, 28 non-ventilated burn victims were interviewed for 5 consecutive mornings during their first week of hospitalization.
- Thirty-nine percent of people reported pain dreams.
- Of those experiencing pain dreams, 30 percent of their total dreams were pain-related.
- Patients with pain dreams showed evidence of reduced sleep, more nightmares, higher intake of anxiolytic medication, and higher scores on the Impact of Event Scale.
- Patients with pain dreams also had a tendency to report more intense pain during therapeutic procedures.
More than half did not report pain dreams. However, these results could suggest that pain dreams occur at a greater frequency in populations currently experiencing pain than in normal volunteers.
One study has linked frontotemporal gamma EEG activity to conscious awareness in dreams.
The study found that current stimulation in the lower gamma band during REM sleep influences on-going brain activity and induces self-reflective awareness in dreams.
Researchers concluded that higher order consciousness is related to oscillations around 25 and 40 Hz.
Recent research has demonstrated parallels between styles of romantic attachment and general dream content.
Assessment results from 61 student participants in committed dating relationships of six months duration or longer revealed a significant association between relationship-specific attachment security and the degree to which dreams about romantic partners followed.
The findings illuminate our understanding of mental representations with regards to specific attachment figures.
Death in dreams
Researchers compared the dream content of different groups of people in a psychiatric facility. Participants in one group had been admitted after attempting to take their own lives.
Their dreams of this group were compared with those of three control groups in the facility who had experienced:
- depression and thoughts about suicide
- depression without thinking about suicide
- carrying out a violent act without suicide
Those who had considered or attempted suicide or carried out violence had were more likely to have dreams with content relating to death and destructive violence. One factor affecting this was the severity of an individual's depression.
Left and right side of the brain
The right and left hemispheres of the brain seem to contribute in different ways to a dream formation.
Researchers of one study concluded that the left hemisphere seems to provide dream origin while the right hemisphere provides dream vividness, figurativeness and affective activation level.
A study of adolescents aged 10 to 17 years found that those who were left-handed were more likely to experience lucid dreams and to remember dreams within other dreams.
Studies of brain activity suggest that most people over the age of 10 years dream between 4 and 6 times each night, but some people rarely remember dreaming.
It is often said that 5 minutes after a dream, people have forgotten 50 percent of its content, increasing to 90 percent another 5 minutes later.
Most dreams are entirely forgotten by the time someone wakes up, but it is not known precisely why dreams are so hard to remember.
Steps that may help improve dream recall, include:
- waking up naturally and not with an alarm
- focusing on the dream as much as possible upon waking
- writing down as much about the dream as possible upon waking
- making recording dreams a routine
Who remembers their dreams?
There are factors that can potentially influence who remembers their dreams, how much of the dream remains intact, and how vivid it is.
Age: Over time, a person is likely to experience changes in sleep timing, structure, and electroencephalographic (EEG) activity.
Evidence suggests that dream recall progressively decreases from the beginning of adulthood, but not in older age. Dream also become less intense. This evolution occurs faster in men than women, with gender differences in the content of dreams.
Gender: A study of dreams experienced by 108 males and 110 females found no differences between the amount of aggression, friendliness, sexuality, male characters, weapons, or clothes that feature in the content.
However, the dreams of females featured a higher number of family members, babies, children, and indoor settings than those of males.
Sleep disorders: Dream recall is heightened in patients with insomnia, and their dreams reflect the stress associated with their condition. The dreams of people with narcolepsy may a more bizarre and negative tone.
Dream recall and well-being
One study looked at whether dream recall and dream content would reflect the social relationships of the person who is dreaming.
College student volunteers were assessed on measures of attachment, dream recall, dream content, and other psychological measures.
Participants who were classified as "high" on an "insecure attachment" scale were significantly more likely to:
- report a dream
- dream frequently
- experience intense images that contextualize strong emotions in their dreams
Older volunteers whose attachment style was classed as "preoccupied" were significantly more likely to:
- report a dream
- report dreams with a higher mean number of words
Dream recall was lowest for the "avoidant" subjects and highest for the "preoccupied" subjects.
Everyone dreams, although we may not remember our dreams. At different times of life or during different experiencs, our dreams might change.
A study investigating anxiety dreams in 103 children aged 9 to 11 years observed the following:
- Females more often had dreams containing anxiety than males, although they could not remember their dreams as often.
- Girls dreamt more often than boys about the loss of another person, falling, socially disturbing situations, small or aggressive animals, family members, and other female people they may or may not recognize.
Studies comparing the dreams of pregnant and non-pregnant women showed that:
- Infant and child representations were less specific in women who were not pregnant. Among those who were pregnant, these images were more likely in the late third trimester than in the early third trimester.
- During pregnancy, dreams were more likely to include the themes of pregnancy, childbirth, and fetuses.
- Childbirth content was higher in the late third trimester than early in the trimester.
- The group who were pregnant had more morbid elements in their dreams than those who were not.
Those that give care to family or people who have long-term illnesses often have dreams related to that individual.
A study following the dreams of adults that worked for at least a year with individuals at United States hospice centers noted:
- Patients tended to be clearly present in the dreams of caregivers, and the dreams were typically realistic.
- In the dream, the caregiver typically interacted with the patient in their usual capacity but was also typically frustrated by the inability to help as fully as desired.
It is widely believed that oppressive dreams are frequent in people going through a time of bereavement.
A study analyzing dream quality, as well as the linking of oppressive dreams in bereavement, discovered that oppressive dreams:
- were more frequent in the first year of bereavement
- were more likely in those experiencing symptoms of anxiety and depression
In another study of 278 people experiencing bereavement:
- Fifty-eight percent reported dreams of their deceased loved ones, with varying levels of frequency.
- Most participants had dreams that were either pleasant or both pleasant and disturbing, and few reported purely disturbing dreams
- Prevalent themes included pleasant past memories or experiences, the deceased being free of illness, memories of the deceased's illness or time of death, the deceased in the afterlife appearing comfortable and at peace, and the deceased person communicating a message.
- Sixty percent felt that their dreams impacted upon their bereavement process.
Does everyone dream in color?
Younger people are more likely to dream in color.
Researchers discovered in a study that:
- About 80 percent of participants younger than 30 years old dreamed in color.
- At 60 years old, 20 percent said they dreamed in color.
The number of people aged in their 20s, 30s and 40s dreaming in color increased through 1993 to 2009. Researchers speculated that color television might play a role in the generational difference.
Another study using questionnaires and dream diaries also found older adults had more black and white dreams than the younger participants.
Older people reported that both their color dreams and black and white dreams were equally vivid. However, younger participants said that their black and white dreams were of poorer quality.
Can dreams predict the future?
Some dreams may seem to predict future events.
Some researchers claim to have evidence that this is possible, but there is not enough evidence to prove it.
Most often, this seems to be due to coincidence, a false memory, or the unconscious mind connecting together known information.
Dreams may help people learn more about their feelings, beliefs, and values. Images and symbols that appear in dreams will have meanings and connections that are specific to each person.
People looking to make sense of their dreams should think about what each part of the dreams mean to them as an individual.
Books or guides that give specific, universal meanings to images and symbols may not be useful.
However, for those who are interested in such books, there is a selection available for purchase online.
One study followed the dream content of people who regularly use crack cocaine in Trinidad and Tobago during a period of abstinence:
- Almost 90 percent of individuals reported drug-related dreams during the first month, mainly of using the drug.
- Almost 61 percent had drug-related dreams after 6 months, mainly of using or refusing the drug.
Vision and hearing loss
People with complete vision loss have fewer visual dream impressions compared with sighted participants.
People who have been unable to see from birth report more auditory, tactile, gustatory, and olfactory dream components, compared with sighted participants.
The ability to see does not appear to affect emotional and thematic dream content.
Those with other abilities
One small study explored the dream diaries of 14 people with impairments.
Four were born with paraplegia, and 10 were born unable to hear or speak.
Deafness: When compared with 36 able-bodied individuals, findings showed that around 80 percent of the dream reports of participants with deafness gave no indication of their impairment.
Many spoke in their dreams, while others could hear and understand spoken language.
Paraplegia: Similarly, the dream reports of those with paraplegia showed that the participants often walked, ran, or swam in their dreams, none of which they had ever done in their waking lives.
A second study looked at the dream reports of 15 people who were either born with paraplegia or acquired it later in life, due to a spinal-cord injury.
Their reports revealed that 14 participants with paraplegia had dreams in which they were physically active, and they dreamed about walking as often as the 15 control participants who did not have paraplegia.
Other research has suggested that the brain has the genetically determined ability to generate experiences that mimic life, including fully functioning limbs and senses.
People who are born without hearing or unable to move are likely tapping into these parts of the brain as they dream about tasks they cannot perform while awake.