Rem Sleep And Dreaming Towards A Theory Of Protoconsciousness Pdf
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Primary consciousness can be defined as simple aware-ness that includes perception and emotion.
- REM sleep and dreaming towards a theory of protoconsciousness
- REM sleep and dreaming towards a theory of protoconsciousness
- REM sleep and dreaming: towards a theory of protoconsciousness and quality during the sleep–wake...
Known for his AIM model of dreaming states and his extensive work on sleep, Allan Hobson is both an experimental researcher and a psychiatrist, and is Professor Emeritus at Harvard Medical School.
REM sleep and dreaming towards a theory of protoconsciousness
The science of dreaming constitutes a relevant topic in modern-day neuroscientific research and provides major insights into the study of human consciousness. Linking specific, universal, and regularly occurring stages of sleep with dreaming encourages the direct and systematic investigation of a topic that has fascinated humankind for centuries. In this review, we explore to what extent individuals dream during periods of rapid eye movement and non-rapid eye movement sleep, and we introduce research on lucid dreaming.
We then discuss how dreaming during different stages of sleep varies in terms of phenomenological characteristics, and to what extent individuals are conscious throughout the sleep cycle. Finally, we provide a synopsis of the previous literature on brain activity during sleep, and we aim to clarify how the neurofunctional changes observed throughout sleep may lead to changes in phenomenological aspects of dreams, and in the domain of consciousness.
Sleep deceives by the ingenuity of its illusions, that there are no certain indications by which we may clearly distinguish wakefulness from sleep.
From death, even. Dreaming may be defined as a mental state, an altered state of consciousness, which occurs during sleep. Dreams usually involve fictive events that are organized in a story-like manner, characterized by a range of internally generated sensory, perceptual, and emotional experiences Desseilles et al. The world of dreams constitutes a major aspect of human experience and has both fascinated and mystified mankind since time immemorial.
Much has been speculated about the origin, meaning, and purpose of dreaming, while the private nature of dreams has made an objective analysis extremely difficult Horikawa et al. The scientific investigation of dreaming only emerged during the late 19th century and primarily focused on factors that influence dream content e. Throughout the past few decades, several biological and psychological theories about the purpose of dreaming have been put forward Lavie and Hobson ; Barbera According to one of the most prominent theories of the origin of dreams, the activation-synthesis hypothesis, dreaming results from rapid eye movement REM sleep physiology Hobson and McCarley More recent theories suggest that dreams fulfil an adaptive function related to emotion-regulation, learning, and memory consolidation e.
Eiser ; Desseilles et al. Dreaming may play an important role in reactivating and further consolidating novel and individually relevant experiences that occurred during waking hours Cipolli et al. It might also constitute a biological defence mechanism, which has evolved as a capacity to repeatedly simulate threatening situations Revonsuo In the present review, we provide an overview of the extent to which dreaming occurs during different stages of sleep and discuss how dreams vary in terms of phenomenological characteristics and consciousness.
To this end, one way of studying a mechanism— such as consciousness—is to examine it in different states of functionality. This is a necessary endeavour to gather a comprehensive understanding of the overall functionality of the mechanism or process in question.
We provide a synopsis of the literature that explored the neural correlates of dreaming and highlight some methodological issues in dream research. Our aim is to clarify how the neural correlates of dreams relate to changes in phenomenological characteristics and features of consciousness throughout sleep. Dreaming often goes unnoticed, and people tend to underestimate how often and how much they dream Nir and Tononi This is due to our tendency to forget dreams, also known as dream amnesia Roth et al.
During the early s, Aserinsky and Kleitman discovered REM sleep, which is characterized by REMs, global high-frequency and low amplitude electroencephalogram EEG activity similar to the waking state , as well as increased heart rate, respiratory activity, and muscle atonia i. In the early days of dream research, dream physiology was equated with REM sleep physiology Aserinsky and Kleitman ; Dement and Kleitman ; Eiser because individuals are most likely to report dreams after awaking from this phase of sleep Maquet et al.
However, it is important to note that REM sleep and dreaming can be dissociated: lesions in the forebrain can leave REM sleep intact while dreaming ceases, whereas brain stem lesions can prevent REM sleep from occurring while individuals continue to report dreams after awakening Solms NREM sleep is characterized by a global low frequency and high amplitude EEG signal, slow and regular breathing and heart rate, as well as low blood pressure.
Sleep inertia i. Dreams that were reported after awakenings from NREM sleep were frequently attributed to confounding factors such as recall of dreams from REM sleep periods or waking confabulations i. However, it is important to note that reports of dreams after awakenings from NREM sleep are not merely a recall of dreams that occurred during the REM sleep phase Nielsen , because 1 dreaming has been reported after awakenings from the first period of NREM sleep before the occurrence of REM sleep Nielsen ; Cavallero et al.
In line with this view, it is important to realize that wakefulness, REM, and NREM sleep are not necessarily mutually exclusive phenomena Mahowald and Schenck ; sleep is far from being homogenous in terms of mental experiences. Hence, dreaming might be described along a continuum, ranging from thought-like mentation that is typical of the early stages of NREM sleep to very vivid dreams that are more typical of REM sleep Desseilles et al.
Lucid dreaming is a rare state of sleep in which individuals achieve awareness of their own state of consciousness. According to the most frequently used sleep scoring criteria, lucid dreaming is considered being a part of REM sleep Rechtschaffen and Kales ; Iber et al. However, recent preliminary evidence suggests that lucid dreaming may also occur during periods of NREM sleep Stumbrys and Erlacher Lucid dreaming has a special status compared with non-lucid REM and NREM dreaming because it is a skill that needs to be trained and occurs only rarely in untrained individuals.
Lucid dreaming itself might occur in different degrees, ranging from pre-lucid reflections i. Since dream lucidity can be trained and signalized in experimental settings by means of the eye-signalling technique LaBerge et al.
Many of the typical qualities of dreaming are similar to our waking experience. Such similarities include the full range of multimodal sensory qualities, colourful visual imagery, occasionally realistic pain perception, as well as almost identical spatial organization i. Interestingly, the phenomenological characteristics of dreams in the various phases of the sleep cycle differ in several ways.
Particularly rich, emotional, and perceptually vivid dream experiences have been reported after awakenings from REM sleep e. Foulkes ; Dresler et al. Dreaming during REM sleep typically follows loose, fanciful, and often very bizarre narratives; relates to current concerns; reflects interests, personality, and mood; draws on long-term memory; and involves social interactions Hall and Van de Castle ; Domhoff ; Fox et al.
The dreamer is often uncertain about time, space, and personal identities and typically has the subjective experience of being awake Schwartz and Maquet Reports of dreaming tend to be most elaborate and bizarre after waking up from the last period of REM sleep Hobson Sensation and perception. Dreams share similarities with experiences during wakefulness, since the perceptual modalities that are utilized most during waking hours also dominate during dreaming Hobson Dream experiences are typically characterized by a range of visual and auditory sensations, physical activities such as self-motion or interaction with objects in the environment, and involve written and spoken language Desseilles et al.
Tactile percepts, odours, tastes, as well as pleasure and pain are not as commonly reported following REM sleep awakenings Hall and Van de Castle ; Domhoff ; Hobson ; Foulkes Oftentimes the sensational and perceptual experiences of the dream world are unlike those which occur in the world of wakefulness.
Alterations from waking life experiences include sensory distortions, misidentifications of characters and places, changes in spatio-temporal integration e. Dreamers tend to report elevated levels of joy, surprise, anger, fear, and anxiety Foulkes et al. A possible explanation for this finding might be less critical self-reflection during dreams Hobson et al. Since REM dream reports frequently contain fear- and anxiety-related elements Valli and Revonsuo , it has been suggested that the realistic representation of fear in dreams and nightmares serves as a threat simulation in a harmless environment in order to prepare individuals for dangerous situations in real life Revonsuo ; Valli et al.
It has also been shown that several periods of dreaming during one night may be related to the same emotional conflict Offenkrantz and Rechtschaffen During the sleep-onset phase, individuals frequently experience hypnagogic hallucinations while being unaware that they have already fallen asleep Underwood These experiences share some similarities with dreams during REM sleep in terms of dream bizarreness but are typically characterized by emotional flatness Foulkes and Vogel ; Vogel et al.
They are often static Hobson et al. Activities that were performed before sleeping might influence the content of such hallucinations Stickgold et al. After the sleep-onset, NREM dreams are typically more thought-like, fragmentary, and related to current concerns, unlike the vivid, hallucinatory, and mainly visual content of REM dreams Eiser After awakenings from sleep stage N3 early during the night, reports tend to be short, thought-like, less vivid, less visual, less motorically animated, less emotional, and less emotionally pleasant than REM reports, while being more conceptual, more plausible, more concerned with current issues, and typically involve greater volitional control Rechtschaffen ; Hobson et al.
Interestingly, dream phenomenology has often been compared with psychosis because dreams share large similarities with many of the typical characteristics of psychosis and particularly with the positive symptoms of schizophrenia e.
These similarities range from internally generated, vivid imagery to intensified and often inappropriate affect as well as diminished ego functions i. Most pronounced are elevated levels and uncritical acceptance of cognitive bizarreness, decreased reality testing, and the delusional belief of being awake while dreaming Limosani et al. Furthermore, the dreamer lacks control of dream events and often shows blunted distinction between first- and third-person perspectives Hobson et al.
These observations are supported by functional magnetic resonance imagining data of psychotic patients, which suggest that dream bizarreness i.
In fact, there are remarkable similarities in terms of cognitive bizarreness between the waking thoughts of individuals with psychosis, their dream reports, and the dream reports of healthy individuals e. Scarone et al. Interestingly though, the psychotic patients differ from the healthy individuals in that they tend to judge their dream reports as less bizarre Lusignan et al. Contrasting the state of lucid dreaming with psychosis, Dresler et al.
Taken together, these findings indicate that there might be a shared mechanism responsible for some of the features of dreaming and psychosis Limosani et al. However, a recent paper by Mota et al. As such, psychosis could potentially amplify the experience of internal stimuli at the expenses of external ones, enabling psychotic patients to better control their internal reality than healthy individuals.
These range from no consciousness to simple awareness of perception and emotion i. In the present review, we use the concepts of primary and secondary consciousness to represent the general notions of sensory awareness and higher level of awareness such as reflection, respectively.
One can generally differentiate between consciousness during wakefulness, consciousness during dreaming, and non-consciousness, with the possibility of intermediate states being present Limosani et al. Consciousness during waking hours is characterized by the awareness of the external world, our bodies, and our selves. When people are dreaming, they are to some extent consciously aware of their internal world, have sensory, perceptual, and emotional experiences but typically fail to recognize their own condition, the bizarre features of the dream world, their poor memory access, and their limited thought capabilities Hobson Dream consciousness and waking consciousness may differ in terms of their origin i.
In line with this notion, it has been suggested that dreams may be seen as a purer form of consciousness, which is free of the constraints imposed by the perception of, and interaction with, physical environments Revonsuo Early reports suggested a single-mindedness and isolation during dreaming, which refers to the dreamer being absorbed in the dream world without being aware of an alternative reality Rechtschaffen However, the nature, level, and quality of conscious experience during sleep show large variability Nir and Tononi To some extent, this might be comparable to the multiplicity of conscious substates that occur during wakefulness e.
Consciousness is clearly not an all-or-nothing phenomenon but a multifaceted concept with aspects varying across species, vigilance states i.
Although there is likely a consensus that consciousness exists while individuals are dreaming, there is an ongoing debate as to whether consciousness exists during dreamless sleep as well Windt et al. Some authors argue that consciousness continues throughout dreamless sleep, provided that one remains aware of having slept. The topic of dreamless sleep is beyond the scope of this paper for further discussions on this issue, please see Thompson ; see also Windt Dreams that occur during REM sleep show mostly aspects of primary but not of secondary consciousness.
During REM sleep, the dreamer tends to have less metacognitive activity i. The dreamer has only limited access to information about the past and anticipated future, and typically concerns him or herself exclusively with the present content of the dream narrative Fox et al.
Goodenough et al. Lucid dreaming is a hybrid state of consciousness with features of both waking and dreaming e. Dresler et al. They found that levels of self-determination i. Furthermore, planning ability i.
However, this may be because it is not necessary to plan during dreams and spontaneous execution of intentions is simply more common.
REM sleep and dreaming towards a theory of protoconsciousness
Dreaming has fascinated and mystified humankind for ages: the bizarre and evanescent qualities of dreams have invited boundless speculation about their origin, meaning and purpose. For most of the twentieth century, scientific dream theories were mainly psychological. Since the discovery of rapid eye movement REM sleep, the neural underpinnings of dreaming have become increasingly well understood, and it is now possible to complement the details of these brain mechanisms with a theory of consciousness that is derived from the study of dreaming. The theory advanced here emphasizes data that suggest that REM sleep may constitute a protoconscious state, providing a virtual reality model of the world that is of functional use to the development and maintenance of waking consciousness. Abstract Dreaming has fascinated and mystified humankind for ages: the bizarre and evanescent qualities of dreams have invited boundless speculation about their origin, meaning and purpose. Publication types Research Support, N.
Dream Consciousness pp Cite as. The role of sleep and dreaming in maintaining emotional stability represents a very tangible and practical example of protoconsciousness as a mental state that supports the proper functioning of normal waking consciousness. Normal sleep has been shown to promote basic mammalian mechanisms of emotion regulation such as habituation, extinction and physiological homeostasis Pace-Schott et al. Sleep deprivation experiments suggest that sleep is also essential to cognitively based emotion regulatory functions such as accurate identification of facial emotion van der Helm et al. Dreaming has been widely hypothesized to take part in this emotion regulatory process. For example, Rosalind Cartwright has suggested that negative affect is progressively ameliorated across dreams elicited from successive REM periods of a night in mildly depressed college students Cartwright et al.
REM sleep and dreaming: towards a theory of protoconsciousness and quality during the sleep–wake...
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The merits of Freudian dream theory continue to be debated and both supporters and critics appeal to empirical evidence to support their respective positions. What receives much less attention is the theoretical coherency of either Freudian dream theory or alternative perspectives. This paper examines Freudian dream theory and J.