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Neuroscience and Biobehavioral Reviews May 2019Lucid dreaming refers to the phenomenon of becoming aware of the fact that one is dreaming during ongoing sleep. Despite having been physiologically validated for... (Review)
Review
Lucid dreaming refers to the phenomenon of becoming aware of the fact that one is dreaming during ongoing sleep. Despite having been physiologically validated for decades, the neurobiology of lucid dreaming is still incompletely characterized. Here we review the neuroscientific literature on lucid dreaming, including electroencephalographic, neuroimaging, brain lesion, pharmacological and brain stimulation studies. Electroencephalographic studies of lucid dreaming are mostly underpowered and show mixed results. Neuroimaging data is scant but preliminary results suggest that prefrontal and parietal regions are involved in lucid dreaming. A focus of research is also to develop methods to induce lucid dreams. Combining training in mental set with cholinergic stimulation has shown promising results, while it remains unclear whether electrical brain stimulation could be used to induce lucid dreams. Finally, we discuss strategies to measure lucid dreaming, including best-practice procedures for the sleep laboratory. Lucid dreaming has clinical and scientific applications, and shows emerging potential as a methodology in the cognitive neuroscience of consciousness. Further research with larger sample sizes and refined methodology is needed.
Topics: Awareness; Brain; Brain Mapping; Brain Waves; Cognitive Neuroscience; Dreams; Humans; Magnetic Resonance Imaging; Metacognition; Transcranial Direct Current Stimulation
PubMed: 30880167
DOI: 10.1016/j.neubiorev.2019.03.008 -
Annals of the New York Academy of... Oct 2017Where do our dreams originate from, and what do they tell us? Is there a universal set of symbols that are common to all dreams, regardless of a person's ethnicity or... (Review)
Review
Where do our dreams originate from, and what do they tell us? Is there a universal set of symbols that are common to all dreams, regardless of a person's ethnicity or culture? What does dreaming reveal about the unconscious? Why do some dreams remain etched in our memories, whereas others are almost instantly forgotten? Some scientists have adopted the position that dreams are little more than noise in the brain, without any substantive purpose or function. Yet, such a stance seemingly runs counter to the experience of many people who reflect upon and even analyze their dreams, often in search of clues to their daily lives or insights into their deeper selves. Similarly, in virtually all wisdom traditions, dreams are invoked as an important source of revelation or prophecy. Steve Paulson, executive producer and host of To the Best of Our Knowledge, moderated a discussion that included psychologist Deirdre Barrett, dream researcher Kelly Bulkeley, and psychologist and sleep/dream medicine specialist Rubin Naiman; they examined dreams from a variety of perspectives to answer these questions.
Topics: Awareness; Brain; Dreams; Humans; Sleep, REM; Unconscious, Psychology; Wakefulness; Webcasts as Topic
PubMed: 28618458
DOI: 10.1111/nyas.13389 -
Neurotherapeutics : the Journal of the... Jan 2021Nightmare disorder and recurrent isolated sleep paralysis are rapid eye movement (REM) parasomnias that cause significant distress to those who suffer from them.... (Review)
Review
Nightmare disorder and recurrent isolated sleep paralysis are rapid eye movement (REM) parasomnias that cause significant distress to those who suffer from them. Nightmare disorder can cause insomnia due to fear of falling asleep through dread of nightmare occurrence. Hyperarousal and impaired fear extinction are involved in nightmare generation, as well as brain areas involved in emotion regulation. Nightmare disorder is particularly frequent in psychiatric disorders and posttraumatic stress disorder. Nonmedication treatment, in particular imagery rehearsal therapy, is especially effective. Isolated sleep paralysis is experienced at least once by up to 40% of the general population, whereas recurrence is less frequent. Isolated sleep paralysis can be accompanied by very intense and vivid hallucinations. Sleep paralysis represents a dissociated state, with persistence of REM atonia into wakefulness. Variations in circadian rhythm genes might be involved in their pathogenesis. Predisposing factors include sleep deprivation, irregular sleep-wake schedules, and jetlag. The most effective therapy consists of avoiding those factors.
Topics: Dreams; Humans; Sleep Paralysis; Sleep, REM
PubMed: 33230689
DOI: 10.1007/s13311-020-00966-8 -
ELife Jun 2020Deep inside the temporal lobe of the brain, the hippocampus has a central role in our ability to remember, imagine and dream.
Deep inside the temporal lobe of the brain, the hippocampus has a central role in our ability to remember, imagine and dream.
Topics: Brain; Dreams; Hippocampus; Mental Recall
PubMed: 32508304
DOI: 10.7554/eLife.58874 -
Nature Neuroscience Jun 2017Consciousness never fades during waking. However, when awakened from sleep, we sometimes recall dreams and sometimes recall no experiences. Traditionally, dreaming has...
Consciousness never fades during waking. However, when awakened from sleep, we sometimes recall dreams and sometimes recall no experiences. Traditionally, dreaming has been identified with rapid eye-movement (REM) sleep, characterized by wake-like, globally 'activated', high-frequency electroencephalographic activity. However, dreaming also occurs in non-REM (NREM) sleep, characterized by prominent low-frequency activity. This challenges our understanding of the neural correlates of conscious experiences in sleep. Using high-density electroencephalography, we contrasted the presence and absence of dreaming in NREM and REM sleep. In both NREM and REM sleep, reports of dream experience were associated with local decreases in low-frequency activity in posterior cortical regions. High-frequency activity in these regions correlated with specific dream contents. Monitoring this posterior 'hot zone' in real time predicted whether an individual reported dreaming or the absence of dream experiences during NREM sleep, suggesting that it may constitute a core correlate of conscious experiences in sleep.
Topics: Adult; Aged; Cerebral Cortex; Dreams; Electroencephalography; Female; Humans; Male; Mental Recall; Middle Aged; Polysomnography; Sleep Stages; Young Adult
PubMed: 28394322
DOI: 10.1038/nn.4545 -
The Lancet. Neurology Oct 2020Dreams are experiences that occur during sleep, while we are disconnected from the environment. Thanks to recent progress in neuroimaging techniques, it is now becoming... (Review)
Review
Dreams are experiences that occur during sleep, while we are disconnected from the environment. Thanks to recent progress in neuroimaging techniques, it is now becoming possible to relate dream features to specific patterns of brain activity. Some conditions occurring in patients with neurological disorders, such as lucid dreams and parasomnias, not only have diagnostic value, but also offer a window into the dream process. They show that dreaming is reflected in physiological signals, behaviours, and brain activity patterns, and that the body can enact dream content. Yet, the dream body can also be distinct from the real body; in their dreams, patients with congenital paraplegia can walk, those with sleep apnoea rarely suffocate, and phantom limb pain can disappear. These conditions provide valuable models for future studies investigating the mechanisms that underlie oneiric experiences.
Topics: Adult; Dreams; Humans; Nervous System Diseases; Sleep; Sleep Stages; Sleep Wake Disorders
PubMed: 32949545
DOI: 10.1016/S1474-4422(20)30275-1 -
Neuroscience Research Apr 2023Dreams are mental experiences, including perceptions, thoughts, and emotions, that occur during sleep. In dreams, hallucinatory perceptions, particularly visual and... (Review)
Review
Dreams are mental experiences, including perceptions, thoughts, and emotions, that occur during sleep. In dreams, hallucinatory perceptions, particularly visual and motoric, are often accompanied by negative emotions. When people dream, they perceive them as real even though they are bizarre and distorted in time and space. People often cannot recall their dreams, even though people dream every night. Dreaming is a strange physiological phenomenon. Research has demonstrated that dreaming is closely associated with rapid eye movement (REM) sleep. It is known that dreaming also occurs during non-REM (NREM) sleep, but the content appears to be different. Dreams during REM sleep tend to be longer, more vivid, more story-like, and more bizarre than those during NREM sleep. In this review, the neural circuits underlying dreaming and the physiological functions associated with it are summarized. Two major theories have been proposed regarding the neural circuits involved in dreaming. One is that dreams are generated by the activation of neural activity in the brainstem and its signal transmission to the cortex. The other is that dreams are caused by forebrain activation by dopamine. Whereas the physiological function of dreams remains unclear, several hypotheses have been proposed that are associated with memory and emotions.
Topics: Humans; Dreams; Sleep; Sleep, REM; Emotions; Mental Recall
PubMed: 36572252
DOI: 10.1016/j.neures.2022.12.017 -
Journal of Sleep Research Aug 2019This consensus paper provides an overview of the state of the art in research on the aetiology and treatment of nightmare disorder and outlines further perspectives on... (Review)
Review
This consensus paper provides an overview of the state of the art in research on the aetiology and treatment of nightmare disorder and outlines further perspectives on these issues. It presents a definition of nightmares and nightmare disorder followed by epidemiological findings, and then explains existing models of nightmare aetiology in traumatized and non-traumatized individuals. Chronic nightmares develop through the interaction of elevated hyperarousal and impaired fear extinction. This interplay is assumed to be facilitated by trait affect distress elicited by traumatic experiences, early childhood adversity and trait susceptibility, as well as by elevated thought suppression and potentially sleep-disordered breathing. Accordingly, different treatment options for nightmares focus on their meaning, on the chronic repetition of the nightmare or on maladaptive beliefs. Clinically, knowledge of healthcare providers about nightmare disorder and the delivery of evidence-based interventions in the healthcare system is discussed. Based on these findings, we highlight some future perspectives and potential further developments of nightmare treatments and research into nightmare aetiology.
Topics: Child; Dreams; Female; Humans; Imagery, Psychotherapy; Male
PubMed: 30697860
DOI: 10.1111/jsr.12820 -
Consciousness and Cognition Oct 2021The understanding of biological functions of sleep has improved recently, including an understanding of the deep evolutionary roots of sleep among animals. However,... (Review)
Review
The understanding of biological functions of sleep has improved recently, including an understanding of the deep evolutionary roots of sleep among animals. However, dreaming as an element of sleep may be particularly difficult to address in non-human animals because in humans dreaming involves a non-wakeful form of awareness typically identified through verbal report. Here, we argue that parallels that exist between the phenomenology, physiology, and sleep behaviors during human dreaming provide an avenue to investigate dreaming in non-human animals. We review three alternative measurements of human dreaming - neural correlates of dreaming, 'replay' of newly-acquired memories, and dream-enacting behaviors - and consider how these may be applied to non-human animal models. We suggest that while animals close in brain structure to humans (such as mammals and birds) may be optimal models for the first two of these measurements, cephalopods, especially octopuses, may be particularly good candidates for the third.
Topics: Animals; Brain; Dreams; Humans; Sleep; Sleep, REM
PubMed: 34653784
DOI: 10.1016/j.concog.2021.103214 -
Neuron May 2024Sleep is a universal, essential biological process. It is also an invaluable window on consciousness. It tells us that consciousness can be lost but also that it can be... (Review)
Review
Sleep is a universal, essential biological process. It is also an invaluable window on consciousness. It tells us that consciousness can be lost but also that it can be regained, in all its richness, when we are disconnected from the environment and unable to reflect. By considering the neurophysiological differences between dreaming and dreamless sleep, we can learn about the substrate of consciousness and understand why it vanishes. We also learn that the ongoing state of the substrate of consciousness determines the way each experience feels regardless of how it is triggered-endogenously or exogenously. Dreaming consciousness is also a window on sleep and its functions. Dreams tell us that the sleeping brain is remarkably lively, recombining intrinsic activation patterns from a vast repertoire, freed from the requirements of ongoing behavior and cognitive control.
Topics: Humans; Consciousness; Sleep; Dreams; Brain; Animals
PubMed: 38697113
DOI: 10.1016/j.neuron.2024.04.011