Under dream or dreams one understands experiencing during sleep . The dream is thus a special form of consciousness . While the body is largely at rest, observed from the outside, the dreamer can experience moving scenes. After awakening, the dreamer can remember his dreams at least to a certain extent. Dreams are usually remembered as "sensual, living, hallucinatory" events and appear "real" at the time of dreaming. The sleeper's reports about his mostly nocturnal experience form the most important access to the contents of consciousness - for example feelings, scenes, experiences, sensations - which are experienced by the sleeper during the dream (1st person perspective). Investigations of the physical correlates of the dream relate to sleep (third person perspective). Physiological correlates , in particular of the brain, are also examined. In psychological approaches to explaining dreams, the two perspectives are preferably worked out into a theoretical position.
Dream as experience in sleep
Dreams are experienced in all phases of sleep (falling asleep, waking up, REM sleep, and NREM sleep ). However, dreams are less common in NREM sleep than in REM sleep. But dreams are rarely remembered. Dream events are often about things and events that are theoretically impossible or improbable in waking reality. But they can also correspond to real processes. Dreams are only partially subject to the control of the ego and are often associated with strong emotional experiences. Cognitive skills such as conceptual thinking and causal- logical remembering take a back seat. There are dreams during which the dreaming is aware of his dreaming state, the so-called lucid dreams. The term lucid dream was coined by the German gestalt psychologist Paul Tholey . Terrifying and anxiety-inducing dreams are called nightmares .
The frequency of dreaming seems to be about the same in all people, although the ability to remember is very different from one individual to another. By taking certain psychotropic drugs , dreaming can be suppressed or the lucid dream experience can be intensified. Targeted meditation before sleep and concentration after waking up can also expand the intensity of the dream experience and the ability to remember.
Dreams and their interpretation had in antiquity a central position with respect to the future and destiny of human existence. During the so-called temple sleep , a practice of dream incubation that has been documented since antiquity, a sick person visited the sanctuary of a god or a hero and hoped there - sometimes in connection with a corresponding ritual and more or less elaborate preparation - in the dream sleep an indication of an effective one To receive therapy for his illness.
The cause and function of the dream have not yet been extensively researched. Various hypotheses have been developed which, depending on the scientific and ideological background, arrive at different conceptions of dreams: For example, dreams are viewed by brain research as a physiological response to neuronal processes, while depth psychology sees it as the effect of unconscious processes.
Hermann Hesse formulated the irrefutable hypothesis "Nobody dreams that is none of his business".
The dream from a critical-realistic point of view
In many dreams, the environment and one's own body appear as realistic as in the waking state. Tholey describes these conditions from the point of view of critical realism , as it is also represented within gestalt theory . This is an epistemological - but not an ontological - dualism . In his sensorimotor approach, Tholey describes the perception and actions within the dream and waking state. The critical-realistic model is the starting point for distinguishing between a physical (trans- phenomenal ) environment and a phenomenal world of experience or perception. The latter is based on the sensual perception of the physical environment and also includes the perception of one's own body. The physical environment is represented in this model in the so-called psychophysical level (PPN), on the basis of the sensory impressions processed there. The hypothetically assumed PPN can be understood as a networked system of different, not firmly localized areas of the cerebrum .
In the waking state, the phenomenal world is formed from the various sensory impressions, understood as an image of the physical world. Desired movements are converted from movement intentions into corresponding movements of the body. These movements are in turn reported back to the PPN via the senses. This establishes a so-called sensorimotor control loop between the physical and the phenomenal world. In the dream state this control cycle is canceled. The phenomenal world is no longer a reflection of the physical world, but is based on the psychological conditions of the sleeper, ultimately on his brain states. Everything that appears directly to the subject is fundamentally part of its own phenomenal world in every state of consciousness. However, while the PPN can intervene in the physical world via sensorimotor control circuits in the waking state, in the dream state no direct impact on the physical environment is possible: Movement intentions are then no longer converted into corresponding movements of the physical body.
In general, dream research is confronted with a central problem: the dream event as experienced by the dreamer is not directly accessible from an empirical point of view. The various approaches to researching the dream phenomenon are divided into three areas.
|Physiological approaches, especially neurobiology||Brain wave measurements (EEG), identification of sleep phases in the brain, research into the brain structures involved, recording of other vital parameters such as heartbeat, breathing or skin conductivity|
|Observable sleep behavior||Eye movements, muscle twitching, change of position, movements of the limbs (e.g. clenching a fist), behavior of dreaming animals during sleep after targeted interventions in the brain|
|Experimental psychology||Examination of the testimonials of test subjects after specific waking in the sleep laboratory during certain sleep phases, during sleep deprivation experiments, after sleepwalking episodes, after or during lucid dreams by means of eye movements agreed before going to sleep , investigation of the effects of external stimuli and daily experiences on the dream, or the effect from dreams to waking life|
So far, there is no generally accepted hypothesis among neurophysiologists about the function of dream and REM sleep . The sleep researcher Jerome Siegel comments: "It is difficult to believe that this physiological state does not play some kind of vital role," but there is no general agreement among sleep researchers about the function of REM sleep.
Medical and scientific research into the dream phenomenon began in Chicago in 1953 with Eugene Aserinsky's discovery of the REM phase in sleep. At the University of Lyon, researchers working with Michel Jouvet were able to localize the pons (also known as the bridge, part of the brain stem ) in 1962 as the area of the brain that controls the sleep phases.
At Harvard University , Allan Hobson and Robert McCarley then developed two influential theories: the reciprocal interaction model and the activation-synthesis hypothesis. which he later extended to the activation-input-output gating-modulation model, or AIM for short. The reciprocal interaction model is a neurobiological description model that explains the change between REM and NREM phases during sleep. With the activation-synthesis hypothesis, Hobson and McCarley try to explain the occurrence of a dream on the basis of their knowledge of the reciprocal interaction model. Neurons in the upper brain stem produce random excitation patterns, which are the starting point for the dream experience. The cortex is confronted with the sleep paralysis of REM sleep, is now seeking to make sensible interpretations of these patterns. The result is a dream. The cause of dreams can thus be assigned to the lower brain functions and, according to this model, the dream itself is “meaningless” or has no meaning. The result was contradicting itself, and not just in psychoanalysis. In addition, more and more anomalies were discovered that could no longer be reconciled with the model. What speaks against the model is the fact that empirical research rarely reports bizarre dream contents that Hobson started out with. Hobson himself therefore restricted his model and made it clear that memory contents play a role in dream formation and dreams are important for unconscious processes. The model also provides only weak explanations for non-rem dreams (NREM dreams), the importance of which has increased in research in the recent past. Today he is of the opinion that the mechanisms he described only act as a switch to “switch” from one dream episode to the next.
The neurophysiologist and psychoanalyst Mark Solms assumes that dreams are generated by higher brain functions and that there is no direct connection between REM sleep and dreams. Solms examined various patients in whom REM sleep no longer occurred due to damage and trauma in REM sleep-relevant areas of the brain. Nevertheless, the patients reported dream activity. On the basis of his empirical results, Solms comes to the old Freudian assumption that the dream is the keeper of sleep .
REM dreams are usually qualitatively different from dreams that are reported outside of REM phases (NREM dreams), or while falling asleep. The NREM dreams reported in up to 70% of the cases seem less vivid, less pictorial, but more real.
The contents of experimental-psychological dream research can be divided into three groups.
Firstly, the description of dreams in order to be able to clearly differentiate them from waking fantasies and thoughts, but also to generate general ways of describing them for better evaluation. Sleep researchers call dream what the dreamer experiences in REM sleep, while they call dreams in the falling asleep phase hypnagogic hallucinations .
Second, the factors influencing dreams, i. H. the question of what effects the previous waking life and external stimuli during sleep have on the dream. Several research groups have examined the extent to which external stimuli are taken over into the dream. Sometimes there was a partial takeover, but often none at all, and in no case did the stimulus become the central dream topic. This difficulty in dissuading the dreamer from his inner invention is what Allan called Rechtschaffen single-minded process. The correlation of the dream with the physiology of the dreamer (eye movement, pulse, breathing, etc.) is also of interest. Here, too, there is still no generally accepted doctrine. While P. Lavie, himself et al. a. relying on the tennis dream in which the dreamer's eye movements coincided with the back and forth of the ball tends to see a connection, this isolated evidence is insufficient for M. Jouvet. In addition, people who are blind from birth experience occasional eye movements during REM sleep, even though they dream in sounds, feelings, and emotional states.
Thirdly, the feedback from experienced dream to waking life, such as after nightmares or creative dreams.
In addition, more speculative questions about the nature of dreams and their content are motivated experiments, such as investigations by u. a. possibility of limited awareness of characters appearing in dreams suggested by Paul Tholey .
Different studies show different factors that have a variable influence on the dream content . The influence of experiences in the waking state decreases exponentially with the period between experience and dream, so experiences from, for example, five days ago are significantly paler than from two days ago. Furthermore, the emotional involvement and the nature of the last watch activities can play a major role. The period between the start of sleep and the start of a dream can affect the time relationships of the dream elements. Dreams in the first REM phases usually contain more current references than dreams in the second half of sleep.
In addition to the internal sources of the dream content, external stimuli occurring at the same time as the dream can have an effect. These are picked up by the human sensory organs and processed accordingly. The sounds of cars driving by, alarm clocks, spoken words, light effects through the closed eyelid and physical impressions (hunger, thirst, urge to urinate) can be considered as stimuli. Research results allow the assumption that depending on the importance of the impression for the person (e.g. after threat) the corresponding stimulus is incorporated into the dream. While the above influencing factors affect the dream, the dream can also affect physical functions. There is a direct influence on eye movements, heart rate and breathing rate. Although a correlation can be demonstrated, the strength and shape cannot be clearly determined.
Dream memory and effects of dreams
People who rarely remember dreams are more likely to report dreams when they are awakened during one of the REM phases of sleep. In a 1999 study, Nielsen and Chenier reported that 82% of study subjects who were awakened during an REM period reported a dream, while 42% of the cases reported it outside of a REM sleep period.
The variance in the extent of dream memory is great both in the individual dreamer and in the amount. For example, individual dreamers report one or more dreams in one night, while other people have the impression that they have hardly or never dreamed. A study that examined the influence of the variables personality factors, creativity, frequency of nocturnal awakenings and attitudes towards dreams on dream memory could not provide an explanation for the variance.
In his sleep laboratory in Haifa , Peretz Lavie studied the frequency of dream reports during REM sleep in different population groups. The test persons were each woken up and questioned when the measuring devices indicated REM sleep. Only 33% of Holocaust survivors who had integrated themselves well into daily life remembered a dream, while the second group of test subjects, Holocaust survivors who still had nightmares and difficulties, remembered 55% of the Cases of a dream, while dream recall in the control group, consisting of people born in Israel, was close to the average value of 78%. There is no explanation of the phenomenon. Lavie suspects that depth of sleep plays a role.
There is a gender difference in dream memory. On average, women remember the dream experience more often than men. Even the simple request to remember dreams or keeping a dream diary can significantly increase the memory of the dreams you have experienced.
There are hardly any systematic studies on the effects of dreams on later waking life. However, previous studies show that nightmares have the strongest influence on the subjective feeling on the day after. Also known are creative impulses that come from nightly dream experiences. The influences in painting ( surrealism ) and music (e.g. Yesterday by the Beatles) are known. In his celebratory speech in 1890 , August von Kekule reported to have seen atoms “dangle” in his mind's eye while he was “half asleep”, and “One of the snakes took hold of its own tail ( Ouroboros ) and sneered at the structure before my eyes. I woke up as if by a bolt of lightning; ... ". With this he found the solution for the ring-shaped benzene structure . Even should Dmitri Mendeleev and (the elements of the periodic table) Elias Howe (sewing machine) have found their solutions in a dream.
|REM dream||Dream that occurs during a REM period of sleep|
|NREM dream||Dream that occurs outside of a REM phase ( sleep phases 2, 3, or 4 )|
|Sleep dream||Dream while falling asleep|
|nightmare||REM dream with fear and panic inducing content that leads to awakening, such as catastrophes, sequences of persecutions, social exposure, personal death, etc.|
|Lucid dream (lucid dream)||Dream in which there is awareness of the dream state. Dream contents can be controlled by the dreamer. Lucid dreams can be used for both creative purposes and research. The in Buddhism occurring dream yoga is based on lucid dreaming. A person capable of lucid dreams is called a oneironaut .|
Function of the dream
In principle, when asked about the function of the dream, a distinction must be made between what function REM sleep has and what function REM dream fulfills in REM sleep. Recent studies confirm the hypothesis that memory consolidation takes place during REM sleep. A connection with the REM dream can be established on the basis of an individual study, but a correlation cannot be reliably proven. The methodological hurdle that a dream can only be examined depending on the waking state is (currently) an insurmountable difficulty in dream research.
Further hypotheses about the function of the dream:
- Leftover from evolution, so no function,
- Brain maturation through REM sleep (the increased REM percentage in newborns serves as evidence),
- Programming with the same patterns over and over to maintain individuality,
- mental function: For Sigmund Freud every dream wish fulfillment and guardian's sleep to it pulses to control,
- Compensation of one-sidedness in order to achieve whole ( CG Jung ), occurrence of archetypes ,
- Dreaming to forget (cleanup function),
- Processing and solving problems from awake life,
- process emotional experiences and smooth out moods,
- State of relaxation for processing fearful content,
- Dreaming is comparable to the training phase of a neural network.
In addition to these "material" hypotheses, there are also ideas that the mind leaves the body in the dream. See also out-of-body experiences .
Historical conceptions of dreams
Already in the Mesopotamian culture, dream-breath huts served next to the temples as dream-catcher places for future foresight and omen interpretation . In Delphi , Greece and Memphis , priestesses interpreted the dreams of pilgrims.
In the Tanach , dreams and their interpretation therefore play an equally important role. So with Jacob's decisions (Genesis 28.12 f and 31.10 f and 37.5 ff). The best known are the dream interpretations of Joseph in Egypt, especially the dream of the seven fat and the seven lean years (Genesis 40: 9 ff), and the Daniels for Nebuchadnezzar II (four-part statue with feet of clay).
Great importance was attached to dream visions among the Indians of North America, including the appointment to medicine man and the execution of rituals, as can be seen from the memories of the Oglala -Sioux Black Deer .
In the medieval and late medieval occident the continuation of the ancient tradition took place through the distribution of so-called dream books .
In the 19th century, however, it was assumed in Europe that dreams were only expressions of physical conditions, which Alfred Maury tried to prove with his experiments. However, in his case, according to the dream researchers, it is not a question of dreams, but of hallucinations during the sleep phase .
Historically significant dreams
Several times throughout history, dreams have been attributed to initiating significant events, such as scientific discoveries and political decision-making, or turning them around for the better. The truth of such decision-making in the dream is not always unequivocally established, in some cases it is definitely legends.
- The ladder to heaven appears to the biblical Jacob in a dream.
- The idea of the Trojan horse is said to have been whispered to the legendary Odysseus by Athene in a dream.
- In the 2nd millennium BC Kabti-ilāni-Marduk , born in BC, is said to have seen the Erra poem in full in a dream before he wrote it down.
- Alexander the Great dreamed of a passage from Homer's Odysseus, in which the island of Pharos appeared. After the dream, he traveled there and founded the city of Alexandria .
- Antigonus I. Monophthalmos , one of the most important diadochi who lived in the third century BC, is said to have seen a field in a dream that made him want to murder Mithridates .
- In a dream, Joseph is said to have been asked by God to flee to Egypt so that Jesus can escape the wrath of Herod. ( Mt 2 : 13-15 EU )
- Constantine the Great defeated Maxentius in the sign of the cross in battle 312, which Christ, who appeared in a dream, had previously meant to him. (see " In hoc signo vinces ")
- The legendary Ursula of Cologne , who is said to have lived in the 4th century, is said to have learned in a dream of her impending martyrdom by a prince of the Huns and the siege of Cologne.
- Cædmon , an English poet of the late 7th century, is said to have been a simple shepherd, according to legend, before he acquired the gift of poetry in a dream.
- The Rhenish folk saint, Termelines , traveled from Ireland to Germany, where he was murdered, in search of a dream location.
- Orgyenpa Rinchen Pel, the supreme lama of the Karma Kagyu, allegedly dreamed of meeting Rangjung Dorje in 1289 , who later became the third Karmapa of the Karma Kagyu school of Tibetan Buddhism.
- The apprentice of the master stonemason, who is said to have built the Rosslyn Chapel in the 15th century, is said to have seen the column arrangement in a dream, whereupon his jealous master killed him.
- In the 17th century, an old bricklayer from Carinthia is said to have been moved by a dream to make a pilgrimage to the Wiblingen Monastery again , where he helped rediscover the Holy Cross relic.
- Elias Howe stated that he saw the two-thread sewing machine he designed in 1835 in a dream in which he sewed for a foreign child.
- George Phineas Gordond claimed in 1851 that Benjamin Franklin described the Gordon crucible press to him in a dream.
- August Kekulé reported that in 1861, half asleep, he blinked into his fireplace and saw hydrogen and carbon atoms dancing there, as well as a snake biting its own tail, which made him use the ring as a symbol for benzene.
- The term Necronomicon , first used by HP Lovecraft in 1922 , is said to have been invented in a dream.
- In January 1938, Franz Jägerstätter saw in a dream a train that more and more people were getting on and heard a voice say: "This train is going to hell". This is one of the reasons why he resisted National Socialism and was therefore murdered.
- When James Cameron fell ill in 1981 while filming Piranha II: The Spawning , a metal torso appeared to him in a feverish dream that - armed with knives - crawled away from an explosion: The idea for the film Terminator was born.
- At the end of the 20th century, Margaret Profet said she was inspired by a dream for her evolutionary explanation of menstruation.
Dream about animals
There is now extensive research into the field of dreaming in animals. The results are to be regarded as preliminary and are currently changing rapidly. Signs of REM sleep have been discovered in birds and almost all mammals. Exceptions are the anticorns (or beak urchins with four species) and platypus . Winson assumes that dreams and especially REM sleep play a role in the consolidation of memory contents. The processing of spatial experience is one of the most important aspects of information storage in animals. The researcher suspects that the prefrontal cortex plays an important role in this. In higher mammals and marsupials , this area of the brain is relatively small, whereas in the Echidna it is very large. Winson suspects that in the course of evolution the development of the brain took place in such a way that instead of processing the content in waking life it was fitted into a sleep phase. As a result, the brain was used during sleep, while the animal is externally at rest. The development by enlarging the brain area was probably not possible due to the dimensions. This is how dreaming evolved. The primitive ant urchin with a large prefrontal cortex, on the other hand, processes the associated information in the awake life and does not dream.
One research method for dreaming in animals is based on experimentally destroying those neurons in the brain stem that suppress movement during sleep. The movements of the animals then show that they are running away, attacking or being frightened by something that is not actually there. From this one concludes that these things occur in the dream experience and one can observe the physical correlate of the dream behavior of the animal.
REM-like sleep was also recently demonstrated in zebrafish . This result is interpreted to mean that sleep could have originated more than 450 million years ago.
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- Jonathan Winson: Neurobiology of Dreaming. In: Brain and Consciousness, Spectrum of Science, pp. 48–56, (here: p. 50). Similar: Michel Jouvet: The Night Side of Consciousness: Why We Dream. Rowohlt, Reinbek near Hamburg, p. 163.
- John A. Lesku, Leith CR Meyer, Andrea Fuller, Shane K. Maloney, Giacomo Dell'Omo, Alexei L. Vyssotski, Niels C. Rattenborg: Ostriches Sleep like Platypuses. In: PLoS ONE; August 2011, 6 (8), e23203, p. 1. PMC 3160860 (free full text)
- Jonathan Winson: Neurobiology of Dreaming. In: Brain and Consciousness, Spectrum of Science, pp. 48–56. P. 51 ff.
- Jonathan Winson: Neurobiology of Dreaming. In: Brain and Consciousness, Spectrum of Science, pp. 48–56, (here: p. 49).
- Both fish and humans have REM-like sleep. In: Science News. July 10, 2019, Retrieved November 20, 2019 (American English).