What are dreams? Why do we have dreams?

Dreams are stories and images that our minds create while we sleep. They can be entertaining, fun, romantic, disturbing, frightening and sometimes bizarre.

Why do dreams occur? Can we control them? What do they mean? We here investigate the current research on dreams and looks at possible explanations and theories as to why our minds invent these nightly musings.

Contents of this article:

1.   What are dreams?
2.   Dream content - what do dreams mean?
3.   Why do we dream?
4.   How do we dream?
5.   What are bad dreams and nightmares?
6.   What are night terrors/sleep terrors?
7.   What are recurring dreams?
8.   What are lucid dreams?
9.   What are wet dreams?
10.   Medication/drugs
11.   Conditions
12.   Why are dreams difficult to remember? How do we remember dreams?

Fast facts on dreams

Here are some key points about dreams. More detail and supporting information is in the main article.

• Though a few people may not remember dreaming, it is thought that everyone dreams between 3 to 6 times per night.
• It is thought that each dream lasts between 5 to 20 minutes.
• Around 95% of dreams are forgotten by the time a person gets out of bed.
• Dreaming can help you learn and develop long-term memories.
• Women dream more about family, children and indoor settings when compared with men.
• Recalling something from last week that has appeared in your dream is called the "dream-lag effect."
• There is a difference in the quality and quantity of dreams experienced in rapid eye movement and non-rapid eye movement sleep.
• 48% of people that feature in a dream are recognized by the person dreaming.
• Blind people dream more with other sensory components compared with sighted people.
• Both sleep and dream quality are affected by alcohol.

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.²⁷ The dreamer has reduced control over the content, visual images and activation of the memory.⁴²

There is no cognitive state that has been as extensively studied and yet as misunderstood as much as dreaming.^40,42

Dreams are full of experiences that have lifelike connections but with vivid and bizarre twists.

There are significant differences between the neuroscientific and psychoanalytic approaches to dream analysis. 

A neuroscientist is interested in the structures involved in dream production and dream organization and narratability. 

However, psychoanalysis concentrates on the meaning of dreams and on placing them in the context of relationships in the history of the dreamer.⁹⁶

Reports of dreams tend to be full of emotional and vivid experiences that contain themes, concerns, dream figures, objects, etc. that correspond closely to waking life.^27,28 These elements create a novel "reality" out of seemingly nothing, producing an experience with a lifelike timeframe and lifelike connections.²⁸

Neuroscience offers explanations linked to the rapid eye movement (REM) phase of sleep as a pinpoint for where dreaming occurs.²⁸

Phases of sleep

There are five phases of sleep in a sleep cycle:

1. Stage 1 - light sleep, eyes move slowly, and muscle activity slows. This stage forms 4-5% of total sleep
2. Stage 2 - eye movement stops and brain waves (fluctuations of electrical activity that can be measured by electrodes) become slower, with occasional bursts of rapid waves called sleep spindles. This stage forms 45-55% of total sleep
3. Stage 3 - extremely slow brain waves called delta waves begin to appear, interspersed with smaller, faster waves. 4-6% of total sleep
4. Stage 4 - the brain produces delta waves almost exclusively. It is very 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 groggy and disoriented for several minutes after they wake up. This forms 12-15% of total sleep
5. Stage 5 - REM - breathing becomes more rapider, 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 - dreams. Forms 20-25% of total sleep time.

Slow-wave sleep refers to stages 3 and 4 of non-rapid eye movement (NREM) sleep.

Dream content - what do dreams mean?

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; those in relationships may dream of their partner; web developers may see programming code. 

These circumstantial observations suggest that during the transition from wakefulness to sleep, elements from the everyday re-emerge in dream-like imagery.⁵⁸

Characters

Studies have examined the "characters" that appear in dream reports and how they are identified by the dreamer.

Most characters that appear in a person's dream are known and can be named by the dreamer.

A study of 320 adult dream reports found:¹

• 48% of characters represented a named person known to the dreamer
• 35% of characters were identified by their social role (e.g., policeman) or relationship to dreamer (e.g., a friend)
• 16% were not recognized.

Among named characters:

• 32% were identified by appearance
• 21% identified by behavior
• 45% by face
• 44% by "just knowing."

Elements of bizarreness were reported in 14% 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 compared to the awake brain, while the paleocortical and subcortical limbic areas are more active. Also proposed was that limbic areas have minimal input from the dorsolateral prefrontal cortex in the dreaming brain.²⁵

Memories

The concept of 'repression' dates back to Freud, whereby undesirable memories can become suppressed in the mind. Dreams ease repression by permitting these memories to be reinstated.

A study showed that sleep does not benefit the forgetting of unwanted memories. Instead, REM sleep might even counteract the voluntary suppression of memories, making them more accessible for retrieval.¹⁵

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 are consistent with the possibility that processing memories into dream incorporation takes a cycle of around 7 days, and that these processes help to further the functions of socio-emotional adaptation and memory consolidation.⁵

A recent study aiming to explore autobiographical memories (long-lasting memories about the self) and episodic memories (memories about discrete episodes or events) within dream content amongst 32 participants found that:

• One dream (0.5%) contained an episodic memory
• The majority (80%) was found to contain low to moderate incorporations of autobiographical memory features.

Researchers suggest that memories for personal experiences are experienced fragmentarily and selectively during dreaming, perhaps in order to integrate these memories into the long-lasting autobiographical memory.²²

A hypothesis stating that dreams reflect waking-life experiences is supported by studies investigating the dreams of psychiatric patients and patients with sleep disorders, i.e., their daytime symptoms and problems are reflected in their dreams.⁵³

In 1900, Freud described a category of dreams - "biographical dreams" - that reflect historical infantile experience without the typical defensive function. Many authors agree that some traumatic dreams perform a function of recovery.

One paper hypothesizes that the predominant aspect of such traumatic dreams is the communication of an experience that the dreamer has in the dream, but does not understand.⁶⁰

Themes

The themes of dreams can be linked to the suppression of unwanted thoughts and, as a result, an increased occurrence of the suppressed thought in dreams.

Fifteen good sleepers were asked to suppress an unwanted thought 5 minutes prior to sleep. The results demonstrated increased dreams about the unwanted thought and a tendency to have more distressing dreams. Moreover, the data imply that thought suppression may lead to significantly increased mental disorder symptoms.⁹

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.¹⁰

Typical dreams are defined as dreams with similar contents reported by a high percentage of dreamers. Up to now, the frequencies of typical dream themes have been studied with questionnaires and these have indicated that a rank order of 55 typical dream themes has been stable over different sample populations.⁸² The 55 dreams themes are:

Flying or soaring through the air is included in the top 10 themes most dreamt about.

1. School, teachers, studying
2. Being chased or pursued
3. Sexual experiences
4. Falling
5. Arriving too late
6. A person now alive being dead
7. Flying or soaring through the air
8. Failing an examination
9. Being on the verge of falling
10. Being frozen with fright
11. A person now dead being alive
12. Being physically attacked
13. Being nude
14. Eating delicious food
15. Swimming
16. Being locked up
17. Insects or spiders
18. Being killed
19. Your teeth falling out/losing your teeth
20. Being tied, unable to move
21. Being inappropriately dressed
22. Being a child again
23. Trying again and again to do something
24. Being unable to find, or embarrassed about using a toilet
25. Discovering a new room at home
26. Having superior knowledge or mental ability
27. Losing control of a vehicle
28. Fire
29. Wild, violent beasts
30. Seeing a face very close to you
31. Snakes
32. Having magical powers
33. Vividly sensing, but not necessarily seeing or hearing, a presence in the room
34. Finding money
35. Floods or tidal waves
36. Killing someone
37. Seeing yourself as dead
38. Being half awake and paralyzed in bed
39. Lunatics or insane people
40. Seeing yourself in a mirror
41. Being a member of the opposite sex
42. Being smothered, unable to breathe
43. Encountering god in some form
44. Seeing a flying object crash
45. Earthquakes
46. Seeing an angel
47. Creatures: part animal, part human
48. Tornadoes or strong winds
49. Being at a movie
50. Seeing extra-terrestrials
51. Traveling to another planet
52. Being an animal
53. Seeing a UFO
54. Someone having an abortion
55. Being an object.

Authors have hypothesized that one cluster of typical dreams (object endangered, falling, being chased or pursued) is related to interpersonal conflicts; another cluster (flying, sexual experiences, finding money, eating delicious food) is associated with libidinal motivations; and a third group (being nude, failing an examination, arriving too late, losing teeth, being inappropriately dressed) is associated with superego concerns.

Senses

Dreams were evaluated in people suffering different types of headache. Results showed people with migraine had increased frequency of taste and smell dreams.

Musical dreams frequency is related to the age of beginning to learn music and not to how much music is listened to throughout the day.

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.¹⁹

Music in dreams is rarely reported in scientific literature. 

However, in a study of 35 professional musicians and 30 non-musicians, the musicians experienced twice as many dreams featuring music 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.⁷⁷

Pain

Although it has been shown that realistic, localized painful sensations can be experienced in dreams - either through direct incorporation or from memories of pain - the frequency of pain dreams in healthy subjects is low.

Twenty-eight non-ventilated burn victims were interviewed for five consecutive mornings during their first week of hospitalization. Results found:

• 39% of patients reported pain dreams.
• Of those experiencing pain dreams, 30% of their total dreams were pain related.
• Patients with pain dreams showed evidence of worse 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 of the sample did not report pain dreams, but these results could suggest that pain dreams occur at a greater frequency in suffering populations than in normal volunteers.⁸⁷

Self-awareness

Recent findings link frontotemporal gamma EEG activity to conscious awareness in dreams. The study found that current stimulation in the lower gamma band during REM sleep influences ongoing brain activity and induces self-reflective awareness in dreams. Researchers concluded that higher order consciousness is related to synchronous oscillations around 25 and 40 Hz.²⁰

Relationships

Recent research has demonstrated parallels between romantic attachment styles 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.⁴¹

Flying

There has been an increase in the percentage of people who report flying in dreams from 1956 to 2000; investigators have proposed this increase may reflect the increasing amount of air travel.⁶⁸

Death

The dream content of psychiatric inpatients who had been admitted because of suicidal attempts was compared with three inpatient control groups who had been admitted for:

• Depression and suicidal ideation without attempt
• Depression with no suicidal ideation
• Commission of a violent act without suicide.

Results confirmed that both suicidal and violent patients have more death content and destructive violence in their dreams, but also that this was a function of the severity of depression and certain character traits such as impulsivity, rather than being specific to the behavior itself.¹⁰⁰

Children

A study investigating anxiety dreams in 103 children aged 9-11 years observed:⁸⁶

Girls dream more often than boys about the loss of another person, of falling, of socially disturbing situations and small animals.

• Girls reported a higher frequency of anxiety dreams than boys, although they could not remember their dreams more often.
• Girls dreamt more often than boys about the loss of another person, of falling, of socially disturbing situations and small animals, of animals as aggressors, of family members (mainly siblings) and other female persons of known identity.

A study of older children and adolescents aged 10-17 years, comparing those with neurotic disorders with healthy subjects, found in left-handers:

• Subjects expressed less novelty factor and frequent appearance of rare phenomena, such as "déjà vu in wakefulness," reality, "mixed" (overlapped) dreams, prolonged dreams in repeat sleep, frequent changes of personages and scenes of action.
• Dream peculiarities detected only in neurotic patients but not in healthy subjects emerged as lucid phenomena deficit, "dream in dreams" and "dream reminiscence in dream" syndrome, only found in left-handers.

Right and left hemispheres seem to contribute in different ways to a dream formation. Authors from the study believe that the left hemisphere seems to provide dream origin while the right hemisphere provides dream vividness, figurativeness and affective activation level.⁸⁸

Pregnancy

During studies comparing the dreams of pregnant and non-pregnant women:^34,92

• Baby and child representations were less specific in the late third trimester than in the early third trimester and than in non-pregnant women.
• Pregnant groups also had more pregnancy, childbirth and fetus themes.
• Childbirth content was higher in late than in early third trimester.
• Pregnant groups had more morbid elements than the non-pregnant group.

Caregivers

Those that give care to family or patients often have dreams related to the person or care given. A study following the dreams of adults that worked for at least a year with patients at US hospice centers noted:³⁶

• Patients were generally manifestly present in participants' dreams, and dreams were typically realistic.
• In the dream, the dreamer typically interacted with the patient as a caretaker but was also typically frustrated by the inability to help as fully as desired.

Bereavement

It is widely believed that oppressive dreams are frequent in bereavement. A study analyzing dream quality, as well as the linking of oppressive dreams in bereavement, discovered:³⁸

• Oppressive dreams occurred at a significantly higher frequency in the first year of bereavement
• Oppressive dreams were significantly associated with anxiety and depressive symptoms.

In another study of 278 bereaved persons:³⁷

• 58% of respondents reported dreams of their deceased loved ones, with varying levels of frequency
• Most participants reported that their dreams were either pleasant or both pleasant and disturbing, and few reported purely disturbing dreams
• Prevalent dream themes included pleasant past memories or experiences, the deceased 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 communicating a message
• 60% of participants felt that their dreams impacted upon their bereavement process.

Does everyone dream in color?

Researchers discovered in a study that about 80% of participants younger than 30 years old dreamed in color. At 60 years old, 20% 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.¹¹⁴

Another study using both questionnaires and dream diaries found older adults also 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 as vivid. However, younger participants said that their black and white dreams were of poorer quality.¹¹⁵

Mistakes/Misidentification

During neuroimaging studies looking at brain activity in REM sleep, scientists found that the distribution of brain activity during REM sleep might also be linked to specific dream features. Several bizarre features of normal dreams have similarities with well-known neuropsychological syndromes after brain damage, such as delusional misidentifications for faces and places.²⁶

Drug abusers

A study following the dream content of crack cocaine abusers in Trinidad and Tobago during abstinence detailed:⁸⁹

• 41 patients reported drug dreams during the first month, mainly of using the drug (89.1%).
• 28 had drug dreams at six months follow-up, mainly of using or refusing the drug (60.9%).

What do blind people dream about?

Studies have shown that blind participants have fewer visual dream impressions compared with sighted participants. Congenitally blind participants reported more auditory, tactile, gustatory, and olfactory dream components compared with sighted participants. Blind and sighted participants did not differ with respect to emotional and thematic dream content.²¹

Paraplegic and those unable to hear or speak

One study explored the dream diaries of 14 people with impairments; four were born with paraplegia and 10 were born deaf and unable to speak. When compared with 36 able-bodied individuals, findings showed that around 80% of the dream reports of the deaf participants gave no indication of their impairment.

Many spoke in their dreams, while others could hear and understand spoken language. The dream reports of the people born paralyzed revealed something similar; they often walked, ran or swam, none of which they had ever done in their waking lives. ¹¹²

There was no difference between the number of bodily movements in the dream reports of the people with paraplegia and those of the deaf and able-bodied subjects.

A second study found similar results. Researchers looked at the dream reports of 15 people who were either born with paraplegia or had it later in life due to a spinal-cord injury. Their reports revealed that 14 of the participants with paraplegia had dreams in which they were physically active, and they dreamed about walking just as often as the 15 able-bodied control participants.¹¹³

Recent dream studies suggest that our brain has the genetically determined ability to generate experiences that mimic life, including fully functioning limbs and senses, and that people who are born deaf or paralyzed are likely tapping into these parts of the brain when they dream about things they cannot do while awake.

Why do we dream?

There are several hypotheses and concepts as to why we dream. Are dreams merely part of the sleep cycle or do they serve some other purpose?

Possible explanations for why we dream include:

• To represent unconscious desires and wishes
• To interpret random signals from the brain and body during sleep
• To consolidate and process information gathered during the day
• To work as a form of psychotherapy.

From converging evidence and new research methodologies, researchers have speculated that dreaming:

• Is offline memory reprocessing - consolidates learning and memory tasks.^79,90,91
• Is a subsystem of the waking default network, which is active during mind wandering and daydreaming. Dreaming could be seen as cognitive simulation of real life experiences.²⁴
• Participates in the development of cognitive capabilities.¹⁷
• Is psychoanalytic; dreams are highly meaningful reflections of unconscious mental functioning.⁷⁹
• Is a unique state of consciousness that incorporates three temporal dimensions: experience of the present, processing of the past, and preparation for the future.⁵⁶
• Provides a psychological space where overwhelming, contradictory, or highly complex notions can be brought together by the dreaming ego that would be unsettling while awake. This process serves the need for psychological balance and equilibrium.⁶⁷

Who dreams?

Evidence from laboratory studies indicates that everyone dreams. Although a small percentage may not remember dreaming at all or claim that they do not, it is thought that most people dream between 3 to 6 times a night, with each dream lasting between 5 to 20 minutes.

There are factors that can potentially influence who can remember their dreams, how much of the dream remains intact and how vivid it is.

Age

Ageing is often associated with changes in sleep timing, structure and electroencephalographic (EEG) activity.

Scientific literature agrees that dream recall progressively decreases from the beginning of adulthood - not in old age - and that dream reports become less intense. This evolution occurs faster in men than women, with gender differences in the content of dreams.⁵⁵

According to a small number of research papers, patients suffering degenerative dementia dream less than healthy older people. In Alzheimer's disease, this could be linked to the decrease of REM sleep and wasting of associative sensory areas of the brain's outer layer.

Gender

A study of 108 male and 110 female dreams found no differences between the amount of aggression, friendliness, sexuality, male characters, weapons, or clothes that feature in the dream's content. However, women's dreams featured a higher number of family members, babies, children, and indoor settings than men.^98,99

In another study, men reported more instances of dreaming about aggression than women. Women had marginally longer dreams with more characters than men. The men in the study dreamt about other men twice as often as they did about women while women dreamt about both sexes equally.

Sleep disorders

Dream recall is heightened in patients with insomnia and their dreams reflect the stress associated with their condition. The stressor of breathing-related dreams in sleep apnea patients is rare, whereas those with narcolepsy have more bizarre and negatively toned dreams.⁶²

Well-being

One study tested the hypothesis that dream recall and dream content would imitate the dreamer's social relationship status. 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 (when compared with participants who scored low on the insecure attachment scale) to:

• Report a dream
• Dream "frequently"
• Have more intense images that contextualize strong emotions in their dreams.

Older volunteers whose attachment style was classed as "preoccupied," were significantly more likely (when compared with participants classified as "securely" attached, as "avoidant" or as "dismissing") to:

• Report a dream
• Report dreams with a higher mean number of words per dream.

Dream recall was lowest for the "avoidant" subjects and highest for the "preoccupied" subjects.²

Dream-lag

Have you ever noticed that often the images, experiences or people that emerge in dreams are images, experiences or people you have seen recently?

People you have seen or experiences you have had a day or a week ago can crop up in dreams. This recalling of a memory within a dream is referred to as dream-lag.

Frequently, details from a dream have been seen before, perhaps the previous day or a week prior to the dream. 

Recalling something from a week ago is known as the "dream-lag effect." The idea is that certain types of experiences take a week to be encoded into long-term memory, and some of the images from the consolidation process will appear in a dream.

Memory theorists suggest that the hippocampus (an area deep in the forebrain that helps regulate emotion, learning, and memory) takes events from the previous day, selects some to be consolidated into long-term memory and then begins to transfer these over to the neocortex (the top layer of the brain that is divided into four major lobes: frontal, parietal, temporal and occipital) for permanent storage. 

The transfer process takes about a week. Dreaming may participate in the relocation of memory storage from hippocampus to neocortex over time.

Events experienced while we are awake are said to feature in 1-2% of dream reports, although 65% of dream reports reflect aspects of recent waking life experiences.

Authors of one study found a significantly higher rate of correspondence between waking life experiences and dream reports when the experiences occurred 1-2, or 5-7 days before the dream, in comparison with when the experiences occurred 3-4 days before the dream.^44,55

The dream-lag effect has been reported in REM but not NREM stage 2 dreams (sleep stages are explained in the next section). These results may provide evidence for a 7-day sleep-dependent memory consolidation process that is specific to REM sleep, and would highlight the importance of REM sleep for emotional memory consolidation.^44,84

How do we dream?

Until REM sleep is completed, the body is essentially paralyzed. This paralysis is caused by the release of glycine - an amino acid - from the brain stem onto the motor neurons (neurons that conduct impulses outward from the brain or spinal cord). REM sleep is the sleep stage at which most dreaming occurs and this paralysis could be nature's way of making sure we do not act out our dreams.

Paralysis during the REM stage of sleep could ensure we do not act out our dreams.

Each complete sleep cycle takes about 90-110 minutes. The first REM sleep period usually occurs around 70 to 90 minutes after we fall asleep. 

The first sleep cycles each night contain relatively short REM periods and long periods of deep sleep. 

As the night progresses, REM sleep periods increase in length while deep sleep decreases. 

By morning, people spend nearly all their sleep time in stages 1, 2, and REM.¹⁰⁷

The relationship between dreaming and strictly REM sleep has been one of controversy amongst researchers with varying hypotheses. Does REM-sleep physiology explain the dream experience, or is REM sleep neither a necessary nor a sufficient condition for dreaming to occur?¹⁴

One study hypothesized that different physiological processes underlie dreaming during REM and non-REM (NREM) sleep. Researchers concluded that although "dreaming" may occur during both REM and NREM periods, as previous researchers have suggested, the dreams obtained from these periods differ significantly in both quality and quantity and are likely to be produced by different processes.⁸

Visual imagery, in a separate study, was reported more often after awakenings from REM compared with stage 2 sleep. These results are consistent with previous researchers who have described REM sleep as a state of high visual hallucinatory quantity, and quality compared with NREM sleep. 83% of REM awakenings compared with only 34% stage 2 awakenings resulted in imagery reports.¹¹

A study proposed that the hormone cortisol plays an important role in controlling the state of memory systems during sleep. 

High levels of cortisol, as are observed late at night and in the context of REM sleep, disrupt normal hippocampal to neocortical communication, which interferes with the form of memory consolidation that is dependent upon this communication. At the same time, the content of dreams is also affected.⁸³

In slow-wave sleep, dream content reflects the normal interaction between hippocampal and neocortical circuits, allowing typical episodic memories to emerge. Normal episodic memories are only retrieved during slow-wave sleep when hippocampal to neocortical communication is functional.

In REM sleep, however, dream content reflects only neocortical activation, which we assume accounts for the fragmented, often bizarre, nature of these dreams.

What are bad dreams and nightmares?

A nightmare is a distressing dream that usually forces at least partial awakening. The dreamer may feel any number of disturbing emotions in a nightmare, such as anger, guilt, sadness or depression, but the most common feelings are fear and anxiety.

Nightmares can cause distressing emotions and can be especially disturbing for children.

Bad dreams, or nightmares are common in both adults and children. They can be caused by:

• Stress
• Fear
• Trauma
• Emotional issues
• Medication or drug use
• Illness.

How do you decide if a dream is considered to be a "bad dream" or a "nightmare"? The content of 9,796 dream reports was collected, which exposed:^32,75

• 253 nightmares - frequently contained physical aggression, situations that were more bizarre and more emotionally intense, containing more failures and unfortunate endings. 35% of nightmares contained primary emotions other than fear.
• 431 bad dreams - frequently contained interpersonal conflicts. 55% of bad dreams contained primary emotions other than fear.

In a study of 840 German athletes from various sports, discussing distressing dreams on the nights before an important competition or game:⁴⁶

• About 15% of the athletes stated that they experienced at least one distressing dream before an important competition or game during the preceding 12 months
• An almost equal number of athletes reported at least one distressing dream in their sports career
• In about 3% of the events, a distressing dream occurred
• Reported dream content referred mainly to athletic failure.

A survey examining the dreams, nightmares, and sleep patterns of 30 women who were dealing with relationship violence found:⁶⁹

• 50% of the sample experienced nightmares on a weekly basis
• Some of the dream images included drowning, being chased, being killed or killing others
• 56% experienced a recurring dream
• Most women had trouble falling asleep and, on average, slept for 6.1 hours per night.

The threat simulation theory of dreaming (TST) states that dream consciousness is essentially an ancient biological defense mechanism, evolutionarily selected for its capacity to repeatedly simulate threatening events.

Children who live in an environment in which their physical and psychological well-being is constantly threatened should then have a highly activated dream production and threat simulation system, whereas children living in a safe environment that is relatively free of such threat cues should have a weakly activated system.

Results of a study with dream reports from severely traumatized and less traumatized Kurdish children and ordinary, non-traumatized Finnish children showed that severely traumatized children reported a significantly greater number of dreams, with their dreams including a higher number of threatening dream events. 

The dream threats of traumatized children were also more severe in nature than the threats of less traumatized or non-traumatized children.⁸⁰

A study of 190 normal school children aged 4 to 12 years reported the following forms of anxiety symptoms:

• Fears - 75.8%
• Worries - 67.4%
• Scary dreams - 80.5%.

Fears of scary dreams were common among children aged 4-6 years old, becoming even more prominent in 7- to 9-year-olds and then decreasing in frequency for 10- to 12-year-olds.

Types of fears, worries, and dreams were found to change across age groups, with fears and scary dreams relating to imaginary creatures decreasing with age. In contrast, worries about test performance increased with age.⁹⁵

Findings from dream reports of 610 boys and girls recalling disturbing and normal dreams at both 13 and 16 years of age highlights how a prevalence of disturbing dreams is especially marked for adolescent girls. Frequent recall of disturbing dreams is associated with pathological symptoms of trait anxiety, even in girls as young as 13 years of age.⁹³

Conditions

Certain conditions appear to increase the frequency of nightmares in individuals such as:

• Migraine: recurrent dreams featuring complex visual imagery, often terrifying nightmares, can occur as migraine aura symptoms.⁹⁴ The brain of migraineurs seems to dream with some peculiar features, all with a negative connotation, as fear and anguish.¹⁸
• Sleep apnea: patients with sleep apnea have more emotionally negative dreams than sleepy snorers.⁵⁰
• Depression: frequent nightmares are associated with suicidal tendency in patients with major depression.⁹⁸

What are night terrors/sleep terrors?

Night terrors are very different from nightmares. The behavior of a child experiencing night terrors may feature:

• Screaming
• Shouting
• Thrashing around
• Panic
• Jumping out of bed
• Inability to recognize parents trying to comfort them.

Night terrors occur on waking abruptly from deep NREM sleep, whereas nightmares are thought to occur during REM sleep.

It is estimated that approximately 1-6% of children in the US experience sleep terror at some point in their childhood. It is common in children aged between 3-12 years. Children are not fully awake in these episodes, even if their eyes are open, and usually have no memory of the event the next day.

The episodes usually occur in the early part of the night and can continue for several minutes (up to 15 minutes).

Night terrors are more common in children with a family history of night terrors or sleepwalking behavior.

A night terror attack may be triggered by anything that:

• Increases how much deep sleep the child has, such as tiredness, fever or certain types of medication.
• Makes the child more likely to wake from deep sleep, such as excitement, anxiety or sudden noise.

Most children will eventually grow out of night terrors.

Studies of twin cohorts and families with sleep terror and sleepwalking suggest genetic involvement of parasomnias (a category of sleep disorders that involve abnormal movements, behaviors, emotions, perceptions, and dreams that occur while falling asleep, sleeping, between sleep stages, or during arousal from sleep).

Restless leg syndrome and sleep-disordered breathing have been shown to have familial recurrence. Restless leg syndrome has been shown to have genetic involvement.¹¹⁷

Night terrors have also been linked to enlarged tonsils and adenoids.

What are recurring dreams?

A recurring dream is a type of dream that occurs on a regular basis when we sleep.

A study of 212 recurrent dreams that were scored using a slightly expanded version of the Dream Threat rating scale showed:⁷⁴

• 66% of the recurrent dream reports contained one or more threats. The threats tended to be dangerous and aimed at the dreamer. When facing a threat, the dreamer tended to take defensive or evasive actions that were possible and reasonable.
• Less than 15% of the recurrent dreams depicted realistic and probable situations that were critical for physical survival or reproductive success. During these dreams, the dreamer rarely succeeded in fleeing the threat despite important and appropriate efforts.

These findings provide mixed support for the threat simulation theory.⁷⁴

Research indicates that recurrent dreams in adults are associated with poor psychological well-being. Authors of a study hypothesized that children reporting recurrent dreams would also show poorer psychosocial adjustment than children without recurrent dreams.

In an examination of dream reports and measures of psychosocial adjustment in 168 children aged 11:⁶¹

• 35% of children reported having experienced a recurrent dream during the past year.
• Boys reporting recurrent dreams reported significantly higher scores for reactive aggression than those who did not.

What are lucid dreams?

Lucid dreaming is a rare state of sleep in which the dreamer gains insight into their state of mind during dreaming; a dream in which the dreamer knows they are dreaming is deemed to be a lucid dream.

Lucid dreams usually occur while a person is in the middle of a regular dream and suddenly realizes that they are dreaming.

Research has shown that lucid dreaming is accompanied by an increased activation of parts of the brain that are normally suppressed during sleep.

A German study revealed significantly increased brain activity during lucid dreams. An EEG machine recorded frequencies in the 40 Hz (or GAMMA) range in lucid dreamers. This is far higher than the normal dream state (THETA range, or 4-7 Hz).

The researchers also saw heightened activity in the frontal and frontolateral areas of the brain - the seat of linguistic thought as well as other higher mental functions linked to self-awareness. This supports the theory that lucid dreaming is a unique state of consciousness separate from any other mental state.¹¹¹

Recent EEG and functional magnetic resonance imaging (fMRI) data found that cortical areas activated during lucid dreaming show striking overlap with brain regions that are impaired in psychotic patients lacking insight into their pathological state.¹⁰³

Results of a study focusing on the distribution of lucid dreams in school children and young adults found:⁶

• Lucid dreaming is quite pronounced in young children
• Incidence rate of lucid dreaming drops at about age 16 years
• Increased lucidity was found in those attending higher level compared with lower level schools.

The study authors proposed a link between the natural occurrence of lucid dreaming and brain maturation.

What are wet dreams?

A wet dream is ejaculation during sleep. Usually, a wet dream happens while a person is having a sexual dream. The person may not even remember the dream.

A person does not have to masturbate to have a wet dream; they ejaculate without touching their penis.

Wet dreams are usually experienced throughout puberty when the body begins production of the male hormone testosterone. Once the body can produce testosterone, it can release sperm.

Wet dreams are a normal part of growing up and cannot be prevented. Some people may experience wet dreams a few times a week; others may only have the experience a couple of times ever.

Not every teenage boy has wet dreams. If boys do not experience wet dreams, there is nothing wrong with them. Although girls cannot ejaculate, they can have an orgasm during a dream. This is less common than with boys.¹¹⁶

Medication/drugs

Antidepressants/SSRIs

Clinical knowledge and a small number of published studies have reported that selective serotonin reuptake inhibitors (SSRIs) intensify dreaming.

A total of 21 clinical studies and 25 case reports were reviewed on the effect of antidepressants on dreaming. Findings of the review include:¹⁰⁴

• In both depressed patients and healthy volunteers, there was a decrease of dream recall frequency with antidepressant use.
• Tricyclic antidepressants induced more positive dream emotions.
• Withdrawal from tricyclic antidepressants and monoamine oxidase inhibitors phenelzine and tranylcypromine caused nightmares.
• Intake and even more withdrawal of SSRIs/SNRIs seem to intensify dreaming.

Anesthetic

Dreams and hallucinations under sedation or anesthesia have been a well-known phenomena since the introduction of anesthesia. Sexual hallucinations may lead to allegations of sexual molestation or assault by medical doctors or professional nursing staff.⁴³

Since the introduction of anesthesia, hallucinations and dreams that are blurred with reality have been frequently reported.

Propofol

There have been cases of propofol-induced hallucinations and dreams in patients described as pleasant, with a frequent "sexual connotation," uninhibited behavior or a verbal expression of patient's intimate thoughts.⁶⁵

Ketamine

Thirty healthy volunteers completed questionnaires about retrospective home dream recall and were then given either ketamine or placebo. The study found:⁶³

• Ketamine resulted in significantly more dream unpleasantness relative to placebo.
• The number of dreams reported over the three nights did not differ between the groups.

Alcohol

A study aiming to investigate sleep quality and the subjective dream experience in alcohol-dependent patients during withdrawal and abstinence compared with healthy controls found:

• Sleep quality was impaired in alcohol-dependent patients during detoxification, and the subjective dream experience was more negatively toned compared with healthy controls.
• Both sleep quality and dream experience improved slightly after four weeks of abstinence.
• Patients with alcohol dependency during withdrawal and abstinence dreamt significantly more often about alcohol.

Subjective sleep and dream quality is strongly impaired in patients with alcohol dependency.⁵¹

Marijuana

Smoked marijuana and oral tetrahydrocannabinol (THC):¹⁰⁵

• Reduce REM sleep
• Increase stage 4 sleep
• Cause strange dreams among acute and subacute cannabis withdrawal
• Increase sleep onset latency, reduce slow-wave sleep, and a REM rebound can be observed.

Conditions

Psychotic major depression

Cognitive bizarreness has been shown to be equally elevated in the dream and waking mentation of acutely symptomatic inpatients diagnosed with affective and non-affective psychoses. A study of patients hospitalized for psychotic major depression (PMD) had similar levels of cognitive bizarreness in their dream and waking mentation.³⁰

Narcolepsy

Narcolepsy with cataplexy (NC) is a neurological disorder characterized by excessive daytime sleepiness and an altered architecture of sleep.

Dream reports were analyzed in NC patients and control participants. While dream recall (about 85%) was comparable in NC patients and controls, first-REM dream reports were longer in NC patients.

Statistical analyses on the NC patients and their matched controls who reported dreams after both REM periods showed that dream experiences occurring in first-REM reports of NC patients were longer and had a more complex organization than those of controls.

These findings suggest that the cognitive processes underlying dream generation reach their optimal functioning earlier in the night in NC patients than in normal subjects.⁶⁴

Parkinson's

The relationship between testosterone levels, violent dreams, and REM sleep behavior disorder (RBD) in 31 men with Parkinson's disease (PD) was examined; 12 with clinical RBD and 19 without.⁷¹

• All PD patients with clinical RBD experienced violent dreams, but none of the 19 non-RBD patients reported violent dreams.
• While dream content appears to be more aggressive in PD patients with clinical RBD, the presence of violent dreams or clinical RBD is not associated with testosterone levels in men with PD.

Another study examined the dream characteristics of PD patients to determine whether dream content differed between patients with RBD and without RBD, men and women with RBD, and men and women with PD.⁷²

• RBD patients had a higher percentage of violent dreams compared to non-RBD patients.
• There were no significant sex differences in the dream content of RBD patients.
• Men with PD had more aggressive dreams compared to females with PD.
• Aggressive dream content was characteristic of RBD patients and sex differences exist in the dream content of the PD population.

Post-traumatic stress disorder

Disturbed sleep patterns, nightmares, and anxiety-filled dreams form a cluster of symptoms belonging to the DSM- IV diagnosis of post-traumatic stress disorder.⁷³

Why are dreams difficult to remember? How do we remember dreams?

It is thought that five minutes after the end of a dream, we have forgotten 50% of its content, and 10 minutes later, we have forgotten 90%. Dream researchers estimate that approximately 95% of all dreams are forgotten entirely upon awakening.

There is something about the phenomenon of sleep that makes it difficult to remember what has occurred. Most dreams are forgotten unless they are written down.

Some people have no difficulty in remembering several dreams nightly, whereas others recall dreams only occasionally or not at all.

Some aspect of the phenomenon of sleep makes it difficult for dreamers to remember what has occurred, and most dreams are forgotten unless they are written down.

Sometimes a dream is suddenly remembered later in the day or on another day, suggesting that the memory is not totally lost but for some reason is very hard to retrieve.¹⁰⁹

Brain lesion and neuroimaging studies converge in indicating that the temporo-parieto-occipital junction and ventromesial prefrontal cortex play crucial roles in dream recall.

Surface EEG studies showed that sleep cortical oscillations associated with successful dream recall are the same as those involved in encoding and recall of episodic memories during wakefulness.⁴⁵

Cortical brain oscillations of human sleep are predictive of successful dream recall. After waking up from REM sleep in the morning, higher frontal 5-7 Hz (theta) activity was associated with successful dream recall. This finding mirrors the increase in frontal theta activity during successful encoding of episodic memories in wakefulness.

A different predictive relationship was found after awakening from stage 2 NREM sleep. Specifically, a lower 8-12 Hz (alpha) oscillatory activity of the right temporal area was associated with a successful dream recall.

These findings provide the first evidence of univocal cortical electroencephalographic correlates of dream recall, suggesting that the neurophysiological mechanisms underlying the encoding and recall of episodic memories may remain the same across different states of consciousness.⁴⁸

In French research, investigators conducted brain scans on 41 people while they were awake and while they slept. Of the participants, 21 remembered dreams about five mornings per week and were labeled "high dream recallers," while the other 20 remembered dreams only two mornings per month. These participants were labeled as "low dream recallers."

When asleep and awake, the high dream recallers showed higher levels of activity in the brain's medial prefrontal cortex and temporo-parietal junction - an information-processing hub.

An Italian research team used technology to measure participants' brain waves during various sleep-stages.

While previous studies have already indicated that people are more likely to remember their dreams when woken directly after REM sleep, this current study explains why. Participants exhibiting more low-frequency theta waves in the frontal lobes were also more likely to remember their dreams.

Increased frontal theta activity is like the successful encoding and retrieval of autobiographical memories seen while we are awake - the same electrical oscillations in the frontal cortex that make the recollection of episodic memories (e.g., things that happened to you) possible. These findings suggest that the neurophysiological mechanisms that we employ while dreaming (and recalling dreams) are the same as when we construct and retrieve memories while we are awake.

In another recent study conducted by the same research team, the authors used the latest MRI techniques to investigate the relation between dreaming and the role of deep-brain structures.

The researchers found that vivid, bizarre and emotionally intense dreams (the dreams that people usually remember) are linked to parts of the amygdala and hippocampus. While the amygdala plays a primary role in the processing and memory of emotional reactions, the hippocampus has been implicated in important memory functions, such as the consolidation of information from short-term to long-term memory.

Scientists have also identified where dreaming is likely to occur in the brain. A very rare clinical condition known as "Charcot-Wilbrand Syndrome," has been known to cause (among other neurological symptoms), loss of the ability to dream. However, recently a patient reported having lost the ability to dream while having virtually no other permanent neurological symptoms.

The patient suffered a lesion in a part of the brain known as the right inferior lingual gyrus (located in the visual cortex), which could suggest that dreams are generated in, or transmitted through, this particular area of the brain, associated with visual processing, emotion and visual memories.

^{There is a huge amount concerning the brain and how it operates while awake or asleep that remains a mystery. Scientists may never pinpoint the exact nature of dreams and why humans need them, but that does not discourage continued research and studies at research facilities looking for an answer.}

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