Dreams

A dream is a series of thoughts, feelings, sensations, and pictures that often arise automatically in the mind during specific sleep stages. Each dream lasts between five and twenty minutes, though the dreamer may think the dream is longer. Humans dream for around two hours per night.

Throughout recorded history, scientists, philosophers, and religious leaders have been interested in the substance and purpose of dreams. Dream interpretation is mentioned frequently in religious scriptures across several religions and has been a key component of psychotherapy since it was first used by the Babylonians in the third millennium BCE and even earlier by the ancient Sumerians. Oneirology is the scientific study of dreams. The majority of current dream research focuses on dream neurophysiology as well as developing and evaluating theories on how dreams work. The genesis of dreams, whether they come from a single place in the brain or from several different places, and the physiological and psychological functions of dreaming are all unknown.

Over time, there have been significant changes in the understanding of the human dream experience. Writings from Mesopotamia and Ancient Egypt claim that dreams influenced post-dream conduct long ago, however this influence decreased significantly in subsequent millennia. These old dream narratives focus on visitation dreams, in which a dream figure—typically a god or a notable ancestor—directs the dreamer to perform particular tasks and sometimes even makes predictions about the future. The way that dreams are framed has changed over time and between civilizations.

Sleep and dreaming are connected. The rapid-eye movement (REM) stage of sleep, when brain activity is intense and mimics being awake, is when dreams mostly happen. Linking dreams to REM sleep has led to theories that animals dream since REM sleep is measurable in many species and research indicates that all mammals experience REM.

But humans also dream while they are not in REM sleep, and not all REM awakenings result in the reporting of dreams. A dream must first be converted to a verbal report in order to be investigated; this report is an explanation of the subject’s recollections of the dream, not the subject’s actual dream experience. Therefore, it is currently impossible to prove that non-human beings dream and that human fetuses or pre-verbal newborns dream.

subjective content and experience

Writings from early Mediterranean cultures that have been preserved suggest that between the end of the Bronze Age and the start of the classical era, there was a quite sudden shift in the subjective nature of dreaming.

Dreamers were often passive in visitation dreams described in ancient literature, with visual material mostly functioning as a framework for authoritative aural messaging. Rebuilding the Ningirsu temple was the dream of Gudea, ruler of the Sumerian city-state of Lagash (c. 2144–2124 BCE), which instructed him to do so. The passive listening to visitation dreams in antiquity was mostly replaced by narratives that could be pictured, in which the dreamer took on the role of an active participant.

Calvin S. Hall gathered about fifty thousand dream reports at Western Reserve University between the 1940s and 1985. The Content Analysis of Dreams, written by Hall and Robert Van de Castle in 1966, described a classification scheme for analyzing 1,000 dream reports from college students. The findings showed that individuals with different backgrounds showed similarities in the substance of their dreams. The inclusion of God under the notable individual’s category in Hall and Van de Castle’s categorization of dream characters is the only remaining vestige of antiquity’s authoritative dream figure. Hall’s protege William Domhoff made all of Hall’s dream reports available to the public in the mid-1990s.

Though they go into greater depth, more recent research on dream reports still gives positive credit to the Hall study.

Anxiety was the most often reported dream emotion in the Hall research. Joy, happiness, anxiety, rage, and abandonment were among the other feelings. Compared to good emotions, negative emotions were far more prevalent. According to the Hall data study, sexual dreams are more common in the early to mid-teens and happen no more than 10% of the time. According to different research, 8% of dreams by both men and women have sexual elements. Orgasms or nocturnal discharges can occasionally be brought on by sexual fantasies. They’re referred to as “wet dreams” informally.

Dreams typically have very phantasmagoric visuals, as many places and objects constantly mix into one another. The images, which include places, people, and things, often mirror the speaker’s recollections and experiences; nevertheless, the discourse can also take on odd and highly exaggerated shapes. Certain dreams can even narrate intricate tales in which the dreamer explores whole unfamiliar, intricate worlds and awakens with concepts, emotions, and sentiments never encountered before.

Individuals who are born blind do not have visual dreams. The contents of their dreams are associated with other sensations that they have experienced from birth, including touch, hearing, smell, and taste.

The Neurophysiological

Research on dreams is popular among scientists studying the mind-brain connection. Others “propose to reduce aspects of dream phenomenology to neurobiology.” However, dream physiology cannot be precisely defined by present knowledge. Most countries’ protocols limit human brain research to non-invasive techniques. Invasive brain operations on human subjects are only permitted in the US when they are thought to be required for surgical therapy to meet the patient’s medical needs. Small but significant neuronal populations cannot be identified by non-invasive brain activity monitoring techniques such as cerebral blood flow, voltage averaging in electroencephalograms (EEGs), or EEGs. Furthermore, real-time brain computation cannot be explained by fMRI signals due to their poor speed.

Examining animal subjects allows scientists to circumvent present limitations when studying certain brain functions. According to the Society for Neuroscience, “Much of this research must [sic] be done on animal subjects because there are no adequate alternatives.” However, there is no definitive data from animal research to shed light on the neurophysiology of dreams because animal dreaming can only be hypothesized and not proved. While lesion methods can be useful in examining human people with brain lesions, they are not selective enough to target particular neuronal groups in diverse areas such as the brain stem, nor can they distinguish between the consequences of destruction and disconnection.

Generation

Too often, dream research has been defeated by the law of the instrument, forced to rely solely on imagery, and denied access to precise instruments. Research finds that there is an increase in blood flow in a certain area of the brain and attributes dream generation to that area of the brain. However, combining research findings has produced a more recent conclusion, suggesting that dreaming includes several areas and pathways, most of which are probably unique to each dream occurrence.

It is hypothesized that “the visual imagery of dreams is produced by activation during sleep of the same structures that generate complex visual imagery in waking perception.” The formation of images in the brain requires a large amount of neuronal activity that occurs downstream from eye intake.

Dreams are not just about visual images; they also tell a story that unfolds over time. After working with split-brain patients, Gazzaniga and LeDoux proposed the idea of a “left-brain interpreter,” which aims to construct a believable story out of whatever electro-chemical signals that make it to the left hemisphere of the brain, without attempting to identify the neurological processes. Research on sleep has shown that certain brain areas that are completely engaged during waking hours are only partially or fragmentarily activated during rapid eye movement sleep.

Drawing on this understanding, textbook author James W. Kalat explains, “Dream represents the brain’s attempt to assemble a coherent story out of fragmented and distorted input. The cortex integrates this random input with whatever other activity was going on and tries to put the pieces together.” Even more direct is neuroscientist Indre Viskontas, who describes often strange dream material as “just your interpreter trying to create a story out of random neural signaling.”

Function theories

Dreams are thought by many people throughout history and culture to have served as messengers of truths received while they slept from gods or other supernatural beings. The ancient Egyptians would induce (or “incubate”) dreams because they thought that this was the greatest method to obtain divine revelation. They sought counsel from the gods, solace, or healing, and slept on special “dream beds” in sanctuaries. From a Darwinian standpoint, dreams would need to satisfy some sort of biological prerequisite, offer some advantage for natural selection to occur, or at the very least, not negatively affect fitness.

The hypothesis that dreams are necessary and serve the purpose of erasing ideas and sensory impressions that were not completely formed during the day was originally put out by Hamburg physician Robert in 1886. Incomplete information is either deepened and incorporated into memory during dreams, or it is eliminated (suppressed). Robert’s theory was challenged by Freud, whose dream studies concentrated on dream interpretation rather than the explanation of how or why people dream. Freud suggested that dreams maintain sleep by interpreting as realized aspirations that would otherwise awaken the dreamer. In contrast to waking up, dreams “serve the purpose of prolonging sleep,” according to Freud’s writing. Sleep is not disturbed by dreams; rather, dreams are its GUARDIANS.”

The Aserinsky and Kleitman study, which was published in Science in 1953 and established REM sleep as a separate sleep phase and connected dreams to REM sleep, marked a watershed in the theory of dream function. Even after the Solms 2000 paper was published, certifying the separability of REM sleep and dream phenomena, much research claiming to explain the purpose of dreams was really investigating quantifiable REM sleep rather than dreams.

The following are some theories on how dreams work since REM sleep was discovered:

The activation-synthesis theory of Hobson and McCarley (1977) postulated “a functional role for dreaming sleep in promoting some aspect of the learning process.” A Harvard research that demonstrated scientific evidence linking dreams to better learning was released in 2010.

The “reverse learning” idea (Crick and Mitchison, 1983) postulates that dreams are similar to computers’ offline cleanup processes, eliminating (suppressing) parasite nodes and other “junk” from the mind while you sleep.

Hartmann’s 1995 theory that suggests dreams have a “quasi-therapeutic” purpose that allows dreamers to process trauma in a secure environment.

According to Revonsuo’s 2000 threat simulation hypothesis, physical and interpersonal hazards were significant during a significant portion of human development, providing survivors with an advantage in reproduction. By simulating these dangers and giving the dreamer the experience of fending them off, dreams promoted survival. The social simulation hypothesis, which Revonsuo introduced in 2015, views dreams as a simulation for forming ties and social skills.

According to Eagleman and Vaughn’s 2021 defensive activation theory, dreams originated as a visual hallucinatory activity during the long dark hours of sleep, engaging the occipital lobe and shielding it from potential appropriation by other, non-vision, sense operations. This theory is supported by the brain’s neuroplasticity.

Based on artificial neural networks, Erik Hoel suggests that dreams help people learn from new situations by preventing overfitting prior experiences.

Religious and other cultural settings

Dreams are central to most major global religions. One explanation is that early people’s dream experiences gave origin to the idea of a human “soul,” a major concept in many religious beliefs. J. W. Dunne penned:

However, there is no plausible question that the observation of dreams by prehistoric man must have been the primary source of the notion of a soul. Despite his ignorance, he was left with little choice but to conclude that during his dreams, he wandered into another dimension and left his sleeping body behind. It is believed that if not for the tribesman, humanity would never have ever pondered the existence of a “soul.”

Hindu

One of the three phases the soul goes through during its existence is a dream, according to the Mandukya Upanishad, one of the Veda texts of Indian Hinduism. The other two states are awake and sleep. Written before 300 BCE, the early Upanishads highlight two interpretations of dreams. According to the first, dreams are only inner wishes expressed. The second is the idea that after departing from the body, the soul is directed until it awakens.

Abrahamic

Dreams are viewed in Judaism as a component of the world experience that may be deciphered and from which lessons can be learned. The Talmud’s Tractate Berachot 55–60 discusses it.

Though they were monotheistic and thought that dreams were the word of a single God, the ancient Hebrews had a close relationship between their religion and dreams. Hebrews also distinguished between dreams that came from God and those that came from wicked spirits.

The Hebrews cultivated dreams in order to acquire a supernatural revelation, much like many other ancient societies did. For example, Joseph deduced that a dream seen by Pharaoh depicting seven lean cows swallowing seven fat cows meant that the next seven years would be abundant, followed by seven years of famine. Similarly, the Hebrew prophet Samuel was said to “lie down and sleep in the temple at Shiloh before the Ark and receive the word of the Lord.” The Book of Genesis contains the majority of the Bible’s dreams.

Because the Old Testament contains several accounts of dreams that were inspired by God, Christians generally held the same views as the Hebrews and believed that dreams were supernatural in nature. Among these dream tales, Jacob’s dream of a staircase connecting Earth and Heaven is the most well-known. Many Christians teach that dreams are a means by which God communicates with humans. The renowned lexicon known as the Somniale Danielis—written under Daniel’s name—tried to instruct Christian communities on how to decipher dreams.

Iain R. Edgar has studied how dreams function in Islam. Since dream interpretation is the sole method Muslims have received revelations from God since the passing of the last prophet, Muhammad, he has maintained that dreams play a significant part in the history of Islam and the lives of Muslims. Edgar claims that there are three categories of dreams in Islam. The real dream (al-ru’ya) comes first, followed by the fake dream (shaytan), which might be the work of the devil, and the pointless daily dream (hulm).

Based on their experiences in the real world, the dreamer’s ego or basic hunger may have prompted this final dream. The hadith tradition of Islam frequently points to the authentic dream. The Prophet’s wife Aisha said that the Prophet’s dreams would materialize like the waves of the ocean. The narrative of Joseph and his extraordinary gift for dream interpretation is told in the Quran, just as it was in its predecessors.

Dreams are mentioned in conversion narratives in both Islam and Christianity. Constantine the Great began his conversion to Christianity as a result of a dream he had while on a campaign, telling him that if he made the Chi-Rho his battle standard, he would win.

Buddhist

Buddhism’s views on dreams are comparable to those of South Asian folklore and classical traditions. Sometimes more than one person has the same dream, like with the Buddha-to-be just before he leaves his home. Premonitory nightmares preceded this for some of the Buddha’s relatives, according to the Mahāvastu. It is also believed that some dreams are timeless; for example, the future Buddha experiences some dreams that are identical to those of earlier Buddhas, the Lalitavistara asserts. Dreams serve as a “signpost” theme to indicate key moments in the protagonist’s life in Buddhist literature.

Buddhist perspectives on dreams are found in the Milinda Pañhā and the Pāli Commentaries.

Other

Two essential components of the soul were described in Chinese history: one is released from the body during sleep to travel in a dream world, while the other remains in the body. Since ancient times, many have questioned this idea and the interpretation of dreams. One such person is the philosopher Wang Chong (27–97 CE).

Dreams were classified as either “bad,” sent by demons, or “good,” sent by the gods by the Babylonians and Assyrians. Iškar Zaqīqu, a collection of dream omens that has survived, describes several dream situations along with predictions about the fate of the dreamer, seemingly based on past experiences.

Some enumerate several conceivable possibilities based on instances where individuals had comparable dreams but distinct outcomes. Greek and Egyptian dream interpretation theories, including the notion of dream incubation, were shared. The Greek deity of dreams, Morpheus, also foretold dire things and sent cautions to anyone who slept in temples and shrines. The earliest Greek theories regarding dreams held that the gods really came to the dreamers, entering via a keyhole and leaving the same way when the dreamer received the heavenly word.

The first known Greek book on dreams was written in the fifth century BCE by Antiphon. Greeks in that century came to believe that spirits departed the body when it slept due to influences from other civilizations. Hippocrates (460–375 BCE), the founder of modern medicine, believed that dreams could diagnose conditions and forecast sickness. For example, a dream of a faint star high in the sky suggested concerns related to the brain, while a dream of a dull star low in the sky suggested problems related to the bowels.

According to the Greek philosopher Plato (427–347), humans have suppressed urges that they carry about with them throughout the day and let loose in their dreams at night. These urges include incest, murder, adultery, and conquest. The pupil of Plato, According to Aristotle (384–322 BCE), dreams result from the body’s inability to fully comprehend physiological activity that occurs when a person is asleep, such as their eyes straining to see through closed eyelids. For his side, Marcus Tullius Cicero held that the ideas and discussions a dreamer had in the days before created all dreams. A long dream vision was reported by Cicero in Somnium Scipionis, and Macrobius remarked on it in Commentarii in Somnium Scipionis.

“The visions that occur to us in dreams are, more often than not, the things we have been concerned about during the day,” says Herodotus in The Histories.

In the animist creation story of the Indigenous Australians, the term “Dreaming” is frequently used to refer to individual or collective creation as well as to what might be thought of as the “timeless time” of formative creation and ongoing creation.

Dreams are seen by certain Indigenous American tribes and people in Mexico as a means of communicating and seeing their ancestors. Vision quests have been used by several Native American tribes as a rite of passage. The participants fast and pray until they get an expected guiding dream, which they then share with the group when they return.

Interpretation

The originator of psychoanalysis, Austrian neurologist Sigmund Freud, postulated that dreams are a reflection of the dreamer’s unconscious mind and that the content of dreams is molded by the unconscious fulfillment of wishes. His theories date back to the late 19th century. He made the case that significant unconscious wants are frequently connected to memories and experiences from early infancy. Freud proposed that the content of dreams reflects the unconscious wishes of the dreamer. Carl Jung and others developed this theory.

Subjective concepts and experiences may influence how dreams are interpreted. According to research, the majority of individuals think that “meaningful hidden truths are revealed in dreams.” Students in the US, Korea, and India were polled by the researchers, who discovered that 74% of Indians, 65% of South Koreans, and 56% of Americans thought their dream content gave them important insight into their underlying aspirations and beliefs. Compared to theories of dreaming that link dream content to memory consolidation, problem-solving, or as a result of unrelated brain activity, this Freudian perspective of dreaming was far more widely accepted. According to the same study, people give dream material greater weight than comparable thinking content that happens during waking hours.

If Americans dreamed of their plane crashing, they were more likely to report that they would purposefully miss their flight than if they thought of it crashing the night before (while awake). If they dreamed of their plane crashing the night before, they were just as likely to miss their flight as if there had been an actual plane crash on the route they intended to take. When the content of dreams matched their views and aspirations while they were awake, research participants were more inclined to believe that dreams had significance.

For example, people were more likely to find significance in a good dream about a friend than in a positive dream about someone they didn’t like, and they were more likely to find meaning in a bad dream about someone they didn’t like than in a terrible dream about someone they loved.

Surveys frequently reveal that people believe their dreams foretell future occurrences in life. Memory biases, including selective memory for precise predictions and distorted memory so that dreams are retroactively fitted onto real-life experiences, have been used by psychologists to explain these experiences. Dreams have many facets, which makes it simple to relate dream material to actual occurrences. The phrase “veridical dream” has been used to describe dreams that disclose or hold secrets or future occurrences that the dreamer is unaware of.

In a particular experiment, participants were instructed to record their dreams in a journal. The selective memory effect was avoided as a result, and the dreams ceased to seem predictive of the future. Participants in a different experiment were given a fictitious student journal whose dreams seemed to be precognitive. The person’s life experiences, some non-predictive dreams, and other predictive dreams were all detailed in this journal. When asked to recollect the dreams they had read, participants were more likely to remember the dreams that came true than the ones that didn’t.

Images and literature

Writers, filmmakers, and graphic designers have all discovered that dreams provide an abundant source of artistic inspiration. In Western art, dream representations from the Renaissance and Baroque periods were frequently connected to biblical stories. The dreams of St. Joseph in the Gospel of Matthew and Jacob’s Ladder in Genesis were particularly favored by visual painters.

Many other graphic artists, such as Western European painters Rousseau (1844–1910), Picasso (1881–1973), and Dali (1904–1989), as well as Japanese woodblock artist Hokusai (1760–1849), have also portrayed dreams.

Dream frames were commonly employed in medieval literature to support the story in allegory; two examples of such dream visions are The Book of the Duchess and The Vision Concerning Piers Plowman. The same tool had been employed by Lucian of Samosata and Cicero much earlier in antiquity.

Since the 19th century, dreams have also been depicted in fantasy and speculative literature. Wonderland from Lewis Carroll’s Alice’s Adventures in Wonderland and Looking-Glass Land from its sequel, Through the Looking-Glass, are two of the most well-known dreamscapes. Carroll’s logic, in contrast to many dream worlds, is based on real dreams, complete with transitions and malleable causation.

Other made-up dream worlds are the Fantastica realm in The Neverending Story and the Dreamlands of H. P. Lovecraft, which have locations like the Swamps of Sadness, the Sea of Possibilities, and the Desert of Lost Dreams. A number of Philip K. Dick’s books, including The Three Stigmata of Palmer Eldritch and Ubik, deal with dreamworlds, shared hallucinations, and other parallel realities. Jorge Luis Borges tackled similar subjects, for example, in The Circular Ruins.

Like Freud, a lot of contemporary popular culture views dreams as manifestations of the dreamer’s most intense wants and anxieties. The distinction between dreams and reality may become even more hazy in speculative fiction in order to forward the plot. Dreams can come true (like in The Lathe of Heaven, 1971) and can be psychically invaded, altered, or even come true (Dreamscape, 1984; The Nightmare on Elm Street series, 1984–2010; Inception, 2010).

Lucidity

The conscious awareness of one’s dream state is known as lucid dreaming. When in this condition, the dreamer frequently has some degree of influence over the things they do in the dream, as well as over the people and surroundings. The capacity to control some components of a dream has been shown to increase with conscious dreaming practice; nonetheless, a dream might be considered “lucid” if it is one in which the dreamer is aware that they are dreaming. Science has confirmed that lucid dreaming does occur.

The word “oneironaut” is occasionally applied to those who have vivid dreams.

A lucid dreamer’s conversation was successfully recorded by psychologist Keith Hearne in 1975. On April 12, 1975, the subject and Alan Worsley, Hearne’s coauthor on the subsequent essay, accomplished this job after the subject agreed to shift his eyes left and right upon becoming lucid. Psychophysiologist Stephen LaBerge carried out comparable research years later, encompassing:

• Mapping the individualized perception of time in dreams using ocular signals.
• contrasting the brain’s electrical activity when dreaming and while singing in the morning.
• Research contrasting orgasm, arousal, and in-dream sex.

It has also been established that two dreamers communicate with each other. EEG monitoring, ocular signaling, reality assimilation through red light stimulation, and a coordinating website were among the mechanisms involved. The stimulus was provided to one of the dreamers, who integrated it into their dream, and the website logged when each dreamer was dreaming. The website recognized this dreamer’s eye movements as an indication of lucidity, at which point it transmitted the stimulation to the second dreamer, evoking inclusion into that dreamer’s dream.

Remembering

While it is a talent that may be learned, dream recall is incredibly inconsistent. If someone is woken during a dream, they often remember what they dreamed. Compared to males, women often remember their dreams more often. Dream recollection is influenced by a number of elements, including salience, arousal, and interference. Dreams that are hard to recall may have very little impact. A dream may frequently be remembered when one sees or hears an arbitrary stimulus or trigger. According to the salience theory, memorable dream material is more likely to be original, dramatic, or unexpected. There is strong evidence that dream material that is vivid, powerful, or uncommon is remembered more frequently.

Dream journals can be used for psychotherapy, personal curiosity, or to help with dream recall.

The typical adult reports recalling two dreams a week. The substance of dreams is usually not recalled unless they are very vivid and unless one wakes up during or just after them.

There is strong evidence that those with more vivid, dramatic, or unusual dreams have superior memory, which supports the salience theory. There is proof that memory and continuity of awareness are connected. In particular, those who have very vivid daytime experiences typically have more remembered dream content and, hence, higher dream recall. Dream recall seems to occur more frequently in those who score highly on personality qualities related to creativity, imagination, and fantasy, such as openness to experience, daydreaming, fantasy proneness, absorption, and hypnotic sensitivity. Additionally, there is proof that the strange elements of dreaming and waking experience are consistent.

In other words, those who report having more strange experiences throughout the day—such as those with high levels of schizotypy, or psychosis proneness—recall their dreams more frequently and also report having nightmares more frequently.

Dream-logging apparatus

One day, dream reconstruction or recording could help with dream memory. Functional magnetic resonance imaging (fMRI) and electromyography (EMG), two permissible non-invasive technologies, have allowed researchers to identify fundamental dream imagery, linguistic activity, and motor action (walking and hand motions).

Miscellany

Deception of actuality

Philosophers have put forth the skeptical hypothesis concerning ontology, which holds that the reality we perceive to be the “real world” may actually be an illusion. The concept was originally mentioned in writing by Zhuangzi in the fourth century BCE, and the issue is known as the “Zhuangzi Paradox” in Eastern philosophy.

If a person dreams of drinking wine, they could cry in the morning; if they dream of crying, they might go hunting. He may even attempt to interpret a dream while he is sleeping as he is unaware that it is a dream. He doesn’t realize it was a dream till he wakes up. And when we realize that all of this is only a fantastic dream, there will be a huge awakening eventually. However, the ignorant think they are awake, working hard and brilliantly as though they comprehend the situation.

They name this man the ruler and that one herdsman—how dim! You and Confucius are both dreaming! Furthermore, I am dreaming as well when I imply that you are. We shall call words like this the Supreme Swindle.

However, it would seem as though he emerged suddenly even when a great sage who understands their meaning may appear after ten thousand generations.

Writings by Buddhists and Hindus also touch on the subject. Descartes brought it to Western philosophy in his Meditations on First Philosophy during the 17th century.

Negligent misconduct

Dreams of absent-minded transgression (DAMT) are those in which the dreamer does something they’ve been trying to stop—lighting a cigarette in a dream, for example—but they do it without realizing it. DAMT subjects have reported experiencing severe guilt after they wake up. According to one study, experiencing these nightmares is positively correlated with effectively quitting the activity.

Non-REM dreams

Though they are shorter than REM dreams, hypnogogic and hypnopompic dreams, dreamy experiences just before and after going to sleep, and dreams during stage 2 of NREM sleep are also possible.

Dreams

A daydream is a kind of visionary imagination that is experienced while awake, usually including positive, pleasant ideas, goals, or desires. Psychologists disagree on the definition of daydreams, which come in a wide variety of forms. The phrase is also widely used by the general population to refer to a wide range of events. According to research by Harvard psychologist Deirdre Barrett, folks who have vivid, dreamlike mental images save the term for these, while most other people associate “daydreaming” with milder imagery, realistic future planning, reviewing memories, or simply “spacing out”—that is, letting one’s mind go relatively blank.

Although daydreaming was often dismissed as a sluggish, pointless past time, it is now widely accepted that daydreaming may be beneficial in certain situations. Daydreaming is a common way for persons in creative or artistic professions, such authors, filmmakers, and musicians, to generate fresh ideas. In a similar vein, researchers in physics, math, and research science have come up with novel ideas by thinking about their fields.

In its widest meaning, a hallucination is a perception that occurs in the absence of a stimulus. More precisely defined, hallucinations are conscious, awake sensations that lack external inputs and have characteristics of genuine perception, such as being vivid, solid, and situated in an external, objective space. The latter concept makes a distinction between hallucinations and the comparable but non-waking phenomenon of dreaming.

Nightmare

A nightmare is an unpleasant dream that has the potential to elicit significant negative mental emotions, such as terror or horror, but also despair, anxiety, and extreme sadness. Situations of peril, pain, or bodily or mental dread may occur in the dream. Those who experience it typically wake up in a distressed mood and may find it difficult to fall back asleep for an extended amount of time.

Fear of the night

A night terror is a parasomnia condition that mostly affects youngsters and causes emotions of fear or dread. It is also referred to as a sleep terror or pavor nocturnus. It’s important to distinguish between nightmares, which are terrifying dreams, and night terrors.

Déjà vu

According to one hypothesis of déjà vu, the sensation of having seen or experienced something before might be attributed to dreaming about a setting or circumstance identical to the one experiencing it, then forgetting about it until an unexplained memory of the setting or scenario arises during waking hours.

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