What Is the Link Between Hallucinations, Dreams, and Hypnagogic-Hypnopompic Experiences?
Flavie Waters, Jan Dirk Blom, Thien Thanh Dang‐Vu, Allan J Cheyne, Ben Alderson-Day, Peter Woodruff, Daniel Collerton
Schizophrenia Bulletin June 29, 2016 DOI: 10.1093/schbul/sbw076 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Review Peer reviewed |
|---|---|
| Topics | Dreaming |
| Keywords | Brain Nerve net Humans Parkinson disease Hallucinations Eye diseases Dreams Sleep, rem Schizophrenia Consciousness Parkinson’s disease Misperception Parasomnia |
| Key findings | The authors argue that sleep-related experiences and hallucinations in Parkinson's disease, schizophrenia, and eye disease share considerable phenomenological and neural overlap, but that key differences remain: sleep-related perceptions are immersive and largely cut off from reality, whereas hallucinations are discrete and overlaid on veridical perceptions, and sleep-related perceptions involve only a subset of the neural networks implicated in hallucinations. They conclude that insufficient evidence exists to fully support the notion that most hallucinations depend on REM processes or REM intrusions into waking consciousness. |
Abstract
By definition, hallucinations occur only in the full waking state. Yet similarities to sleep-related experiences such as hypnagogic and hypnopompic hallucinations, dreams and parasomnias, have been noted since antiquity. These observations have prompted researchers to suggest a common aetiology for these phenomena based on the neurobiology of rapid eye movement (REM) sleep. With our recent understanding of hallucinations in different population groups and at the neurobiological, cognitive and interpersonal levels, it is now possible to draw comparisons between the 2 sets of experiences as never before. In the current article, we make detailed comparisons between sleep-related experiences and hallucinations in Parkinson's disease, schizophrenia and eye disease, at the levels of phenomenology (content, sensory modalities involved, perceptual attributes) and of brain function (brain activations, resting-state networks, neurotransmitter action). Findings show that sleep-related experiences share considerable overlap with hallucinations at the level of subjective descriptions and underlying brain mechanisms. Key differences remain however: (1) Sleep-related perceptions are immersive and largely cut off from reality, whereas hallucinations are discrete and overlaid on veridical perceptions; and (2) Sleep-related perceptions involve only a subset of neural networks implicated in hallucinations, reflecting perceptual signals processed in a functionally and cognitively closed-loop circuit. In summary, both phenomena are non-veridical perceptions that share some phenomenological and neural similarities, but insufficient evidence exists to fully support the notion that the majority of hallucinations depend on REM processes or REM intrusions into waking consciousness.
Comparable studies
Other narrative reviews on dreaming, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| The cognitive neuroscience of lucid dreaming | 2019 | Review | |
| Sleep and dreaming are for important matters | 2013 | Review | |
| Nightmare Disorder and Isolated Sleep Paralysis | 2020 | Review | |
| My Dream, My Rules: Can Lucid Dreaming Treat Nightmares? | 2019 | Review | |
| Dream Recall: State or Trait Variable? Part I: Model, Theories, Methodology and Trait Factors | 1996 | Review |
Citations in the library
Cited by 50
- Severe Sleep Deprivation Causes Hallucinations and a Gradual Progression Toward Psychosis With Increasing Time Awake Frontiers in Psychiatry July 10, 2018
- Beyond Trauma: A Multiple Pathways Approach to Auditory Hallucinations in Clinical and Nonclinical Populations Schizophrenia Bulletin August 8, 2018
- Occurrence and phenomenology of hallucinations in the general population: A large online survey Schizophrenia April 23, 2022
- The hypnagogic state: A brief update Journal of Sleep Research August 26, 2022
- Psychedelics as potential catalysts of scientific creativity and insight Drug Science, Policy and Law 2022
and 45 more in the library
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