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Hypnagogic and Hypnopompic Hallucinations during Sleep Paralysis: Neurological and Cultural Construction of the Night-Mare
Abstract
Hypnagogic and hypnopompic experiences (HHEs) accompanying sleep paralysis (SP) are often cited as sources of accounts of supernatural nocturnal assaults and paranormal experiences. Descriptions of such experiences are remarkably consistent across time and cultures and consistent also with known mechanisms of REM states. A three-factor structural model of HHEs based on their relations both to cultural narratives and REM neurophysiology is developed and tested with several large samples. One factor, labeled Intruder, consisting of sensed presence, fear, and auditory and visual hallucinations, is conjectured to originate in a hypervigilant state initiated in the midbrain. Another factor, Incubus, comprising pressure on the chest, breathing difficulties, and pain, is attributed to effects of hyperpolarization of motoneurons on perceptions of respiration. These two factors have in common an implied alien "other" consistent with occult narratives identified in numerous contemporary and historical cultures. A third factor, labeled Unusual Bodily Experiences, consisting of floating/flying sensations, out-of-body experiences, and feelings of bliss, is related to physically impossible experiences generated by conflicts of endogenous and exogenous activation related to body position, orientation, and movement. Implications of this last factor for understanding of orientational primacy in self-consciousness are considered. Central features of the model developed here are consistent with recent work on hallucinations associated with hypnosis and schizophrenia.
... 7 These hallucinations typically fall into three categories. 8,9 Intruder hallucinations consist of a sense of evil presence in the room, along with vivid multisensory hallucinations of a bedroom intruder. Incubus hallucinations describe a sense of pressure on the chest, often accompanied by sensations of being choked or suffocated. ...
... These two categories of hallucinations typically co-occur. 8 The third category, vestibular-motor (V-M) hallucinations involve illusory feelings of movement, out-of-body feelings, and out-of-body autoscopy. 9 It is possible that the hallucinatory content of sleep paralysis may result from the intrusion of REM-generated dream mentation into wakefulness. ...
... The vast majority (up to 90%) of sleep paralysis episodes are associated with fear. 8 This contrasts with ~30% of dreams being rated as frightening. 10 In a study comparing the contents of sleep paralysis and dream reports, sleep paralysis episodes were found to be emotionally uniform, feature more aggressive "characters," and the "dreamer" was more frequently the victim of attacks compared with typical dreams. ...
... SP episodes manifest as an inability to move (muscle atonia) as in normal sleep, but the person stays awake [1,2]. It often proceeds with hypnopompic and hypnogogic hallucinations: visual, tactile, kinesthetic, auditory, and less often olfactory [3][4][5]. There are three types of hallucinations typical of SP: (1) the "intruder", associated with a sense of a threatening/hostile presence, fear, auditory and visual hallucinations (often a shadow or dark form); (2) the "incubus", associated with a feeling of tightness or pain on the chest, breathing difficulties, and sometimes visual In the general population, one of the most common sleep disorders is insomnia, and its prevalence is estimated to range between 6 and 15%, while poor-quality sleep is experienced by up to 30% of people around the world [15]. ...
... [10]. The course of SP episodes in the groups we studied was typical, as already described by other researchers [3,5,49,50]. Study participants reported the presence of hypnopompic and hypnagogic hallucinations of various modalities. ...
... Study participants reported the presence of hypnopompic and hypnagogic hallucinations of various modalities. They also described hallucinations characteristic of SP, as described by Cheyne et al.: intruder, incubus and vestibular-motor [3]. The types of hallucinations reported did not differ significantly between studied groups. ...
Sleep paralysis (SP) is a hypnagogic or hypnopompic state associated with the inability to move while conscious. Recurrent isolated sleep paralysis (RISP) is a type of REM parasomnia. Individuals experiencing anxiety disorders, PTSD, exposure to chronic stress, or shift work are at risk of developing this sleep disorder. This study aimed to assess: (1) the prevalence, frequency, and symptomatology of SP, and (2) the impact of the severity of anxiety symptoms, perceived stress, and lifestyle mode variables on the frequency and severity of SP in four professional groups at high risk of SP (n = 844): nurses and midwives (n = 172), policemen (n = 174), teachers (n = 107), and a group of mixed professions—“other professions” (n = 391). The study used a battery of online questionnaires: the Sociodemographic and Health Status Questionnaire, the SP-EPQ, the PCL -5, the STAI-T, the PSWQ and the PSS-10. The prevalence of SP was the lowest among policemen (15.5%) and the highest in the group of “other professions” (39.4%). The association of SP with symptoms of PTSD and anxiety was confirmed in the group of nurses and “other professions”. Among other factors modulating the incidence and severity of SP were: age, BMI, smoking, alcohol consumption, sleep duration, and perceived stress. This study indicates that there exist links between SP and psychological and lifestyle factors, suggesting a complex etiology for this sleep disorder. Due to the high prevalence of SP in the studied groups of occupations, further research is necessary to develop preventive and therapeutic methods for SP.
... Muscle atonia, which occurs several times nightly during normal REM sleep (Molendijk et al., 2017), persists into the waking stage and the sleeper's awareness, creating a sense of paralysis. Remarkable congruence in the characteristics associated with SP is found cross-culturally and historically (Cheyne et al., 1999;Jalal et al., 2021). The widespread and profound impact of SP on the human psyche is evident in that SP is found in mythology, lore, and literature worldwide Rees & Whitney, 2020;Stefani & Högl, 2021). ...
... In a majority of SP cases, individuals do not present with sufficient distress to warrant this diagnosis (Sharpless & Kliková, 2019), yet are often clearly discomfited by their experiences, expressing both fear and efforts to prevent future episodes (Sharpless & Grom, 2016). Vivid subconscious content intrudes into consciousness in approximately 75% of SP cases (Cheyne et al., 1999;Sharpless et al., 2010;Sharpless & Grom, 2016), often registering as terrifying and somewhat stereotyped hallucinations, with common themes including a malevolent presence or leaving one's body (Cheyne 2003;Denis & Poerio, 2017;Stefani & Högl, 2021). A small minority of SP episodes are perceived as pleasant (Kliková et al., 2021). ...
... High SP frequency could create significant additional affective burden for those already struggling with traumatic grief, because a great majority of SP experiencers report fear with the episodes, both in this study and in prior research (eg. Cheyne et al., 1999;Jalal et al., 2021;Sharpless et al., 2010;Sharpless & Gromm, 2016). About half the participants in this study also specifically feared death during their episodes; a similar rate to that found by Jalal et al. (2021), using the same measure. ...
Adverse life events are associated with the often-terrifying REM sleep parasomnia of sleep paralysis (SP), but the impact of bereavement on SP has not been specifically examined. This exploratory, mixed-methods study (N = 168) includes qualitative data from 55 participants who described factors they believed led to their SP. Of these, almost half with a traumatic loss listed death-related precipitants. In unadjusted (bivariate) negative binomial regression models, traumatic death, time since death, religiosity, and age estimated increased SP frequency in the prior month, prior year, or both. In multivariable models, traumatic death, time since death, and age estimated increased frequency in the prior month, prior year, or both. Unexpectedly, in all models, as compared to death ≥9 years earlier, prior month SP was greater with death 1-6 years earlier, but not <1 year earlier. Discussion includes the possible role of social constraints in traumatic grief trajectories and care provider recommendations.
... respectively. 10,11 In addition, sleep-related factors, such as sleep deprivation, shift work, jet lag, and a few medical conditions, such as hypertension,seem to have a connection with SP. [12][13][14] The presence of nightmares play a core role factor for more frequent episodes of SP. 10 Nevertheless, people's perceptions of SP as a supernatural power can be a risk factor of SP. [15][16][17] In Saudi Arabia, SP is described as Al-Jathoum, and a case study in which a Saudi patient, who at first complained of sleep disruption due to driving long distances and nightmares, described it as a type of alien power, likely to be jin that squeezed his chest for a period of time. 18 There is an ultimate need to conduct this study due to the significance of the prevalence of SP worldwide, and the importance of identifying SP as a medical condition rather than cultural misconceptions. ...
... 14 This study has shown that the supine position was the most common sleeping position for participants when SP occurred. Among the few studies on the association between SP and sleeping position, a study by Cheyne et al 12 found that a greater number of individuals reported SP in the supine position than all other positions combined. ...
... Saudi Med J 2021; Vol. 42(12) Awareness of sleep paralysis phenomenon ... Aledili et al ...
Objectives:
To assess prevalence and perception of sleep paralysis and its relationship with socioeconomic determinants, and risk factors in a cross-sectional sample of Saudi general population from Al-Ahsa city.
Methods:
A cross-sectional sampling survey was conducted during 2020 to 2021. The targets were aged above 18 and belonged to Al-Ahsa. Patients were sent self-reported anonymous questionnaires to complete.
Results:
A total of 524 participants, whose ages ranged from 18 to 60 years, were analyzed. Among 85.7% of participants aged 55 years and over, compared to 65.8% of those who were aged under 35, 379 (72.3%) respondents were females. Moreover, 438 (83.6%) participants were university graduates, 271 (51.7%) were students and 40.8% had psychological disorders including anxiety (25.2%) and depression (5.7%). Family history of sleep paralysis was reported by 369 (70.4%) participants. A total of 97.5% study participants were aware of sleep paralysis.
Conclusion:
Sleep paralysis is a common occurrence in people residing in Al-Ahsa, Saudi Arabia. A considerable number of the society held wrong beliefs regarding sleep paralysis. Therefore, raising public of identity of sleep paralysis is crucial. We recommend applying the study in other cities within Saudi Arabia to identify common risk factors and perceptions among the society.
... SP is often associated with severe anxiety [1,9,[20][21][22], and cultural interpretations of SP (e.g., as a supernatural experience) seem to exacerbate its severity. In Egypt, where SP is regarded as a supernatural experience, 50% of respondents reported fear of death. ...
... Ninety-three percent of study participants reported that they experienced fear during SP, and 46% reported a specific fear of death. The most similar result was obtained in a Canadian study in which 90% of participants reported anxiety [21]. For comparison, in Ireland, fear was reported by 82% and fear of death by 39.8% [52]. ...
... The most frequently reported somatic symptom was perceived feelings of the heart beating faster (76% of respondents). Other studies have also reported the presence of symptoms such as feelings of pressure [9,21,29,51], difficulty breathing, pain, light-headedness, and dizziness [21], smothering, numbness, vibrating, tingling sensations and feeling numbness [29]. , described the presence of multiple somatic symptoms such as palpitations and shortness of breath during sleep paralysis among Cambodian refugees that include extremely high rates of panic [6,53]. ...
Sleep paralysis (SP) is a psychobiological phenomenon caused by temporary desynchrony in the architecture of rapid eye movement (REM) sleep. It affects approximately 7.6% of the general population during their lifetime. The aim of this study was to assess (1) the prevalence of SP among Polish students in Lublin (n = 439) using self-reported online surveys, (2) the frequency of SP-related somatic and psychopathologic symptoms, and (3) the factors potentially affecting the occurrence of symptoms among people experiencing SP. We found that the incidence of SP in the Polish student population was slightly higher (32%) than the average prevalence found in other student populations (28.3%). The SP clinical picture was dominated by somatic symptomatology: 94% of respondents reported somatic symptoms (most commonly tachycardia, 76%), 93% reported fear (most commonly fear of death, 46%), and 66% reported hallucinations (most commonly visual hallucinations, 37%). The number of SP episodes was related to sleep duration and supine position during sleep. The severity of somatic symptoms correlated with lifestyle variables and anxiety symptomatology. Our study shows that a significant proportion of students experience recurrent SP and that this phenomenon is associated with fear and physical discomfort. The scale of the phenomenon requires a deeper analysis.
... 2 SP is a component of narcolepsya neurological disorder, 3 but it can also occur independently of the condition. 4 SP occurring outside of narcolepsy is referred to as isolated sleep paralysis (ISP) 5 , and SP episodes involving clinically significant levels of fear have been termed fearful ISP. 6 Individuals who experience recurrent episodes of ISP and significant clinical distress may meet criteria for the disorder of recurrent ISP. 1 More stringent clinical criteria have also been developed for use in research (i.e., fearful recurrent isolated sleep paralysis) which include frequency thresholds (i.e., at least two fearful ISP episodes in the past six months) and the presence of either clinically-significant distress and/or impairment. ...
... 6 Individuals who experience recurrent episodes of ISP and significant clinical distress may meet criteria for the disorder of recurrent ISP. 1 More stringent clinical criteria have also been developed for use in research (i.e., fearful recurrent isolated sleep paralysis) which include frequency thresholds (i.e., at least two fearful ISP episodes in the past six months) and the presence of either clinically-significant distress and/or impairment. 6,7 While a benign phenomenon on its own, 8 there is often a lot of fear and anxiety surrounding SP. 5 For example, out of 635 college students who had experienced SP in Japan, 60% reported feelings of anxiety and terror during an episode. 9 Subsequent research has reported associations between anxiety, stress, and SP episodes. ...
Study objectives:
Isolated sleep paralysis is a benign but frightening condition characterised by a temporary inability to move at sleep onset or upon awakening. Despite the prevalence of this condition, little is known concerning its clinical features, associated demographic characteristics, and prevention as well as disruption strategies.
Methods:
An online cross-sectional study was conducted. The sample comprised 3523 participants who had reported at least one lifetime episode of ISP and 3288 participants without a lifetime episode. Participants answered a survey including questions about sleep quality, sleep paralysis, and sleep paralysis prevention/disruption techniques.
Results:
A total of 6811 participants were investigated (mean age = 46.9, SD = 15.4, age range = 18-89, 66.1% female). Those who reported experiencing ISP at least once during their lives reported longer sleep onset latencies, shorter sleep duration, and greater insomnia symptoms. Females (vs. male) and younger (vs. older) participants were more likely to experience ISP. Significant fear during episodes was reported by 76.0% of the participants. Most people (63.3%) who experienced ISP believed it to be caused by 'something in the brain'. A minority endorsed supernatural causes (7.1%). Five prevention strategies (e.g., changing sleep position, adjusting sleep patterns) with at least 60.0% effectiveness, and five disruption strategies (e.g., physical/bodily action, making noise) with varying degrees of effectiveness (ranging from 29.5 to 61.8) were identified through open-ended responses.
Conclusions:
ISP is associated with shorter sleep duration, longer sleep onset latency, and greater insomnia symptoms. The multiple prevention and disruption techniques identified in this study support existing treatment approaches and may inform subsequent treatment development. Implications for current diagnostic criteria are discussed.
... When I think about something relaxing, it all goes away" [sic]. This coincides with the role suggested for a hypervigilant state initiated in the midbrain (35), with psychological as well as neurobiological components. Although this is in need of further study, this might also explain why all the participants in the patient group who experienced a sleep paralysis went on to develop an incubus phenomenon (vs. ...
... The underlying theory of the incubus phenomenon, formulated by Cheyne et al. (35), has become known as the experiential source hypothesis, which holds that the neurobiological underpinnings of the phenomenon are hardwired, whereas its phenomenological features depend on attributional styles, which are in turn steeped in cultural and religious values. The threat-activated vigilance system is a neural network in which the midbrain and the amygdala play important roles. ...
Background
The incubus phenomenon is a paroxysmal sleep-related disorder characterized by the visuotactile sensation of a person or entity exerting pressure on one’s thorax during episodes of sleep paralysis and (apparent) wakefulness. This terrifying phenomenon is relatively unknown even though a previous meta-analysis indicated a lifetime prevalence of 0.11 for individuals in the general population and of 0.41 for selected at-risk groups, including people diagnosed with schizophrenia and students. Since the studies reviewed did not always make a strict distinction between the incubus phenomenon and isolated sleep paralysis, we carried out a cross-sectional study in a contemporary patient and student sample to attain current, more detailed data on the incubus phenomenon.Materials and methodsIn a cross-sectional design, we used the Waterloo Unusual Sleep Experience Questionnaire (WUSEQ) to screen patients with severe psychiatric disorders and university undergraduates to establish and compare prevalence rates, frequencies of occurrence, and risk factors for the incubus phenomenon.ResultsHaving interviewed 749 people, comprising 606 students and 143 patients with a schizophrenia spectrum or related disorder who had been acutely admitted to a secluded nursing ward, we computed a reported lifetime prevalence of 0.12 and 0.09, respectively, which rates were not statistically different. In both groups, the phenomenon was more common in people with a non-Western European background. Risk factors noted for the students were the use of psychotropic medication and the lifetime presence of an anxiety disorder, eating disorder, or sleeping disorder. We found no associations with age or gender in either group.Conclusion
The 0.09 and 0.12 lifetime prevalence rates we recorded for the incubus phenomenon in students and psychiatric inpatients is substantially lower than the 0.41 found in an earlier meta-analysis. We tentatively attribute this difference to an overgeneralization in previous studies but also discuss alternative explanations. The elevated prevalence among non-Western European participants may well be due to the fact that the topic continues to be part of the cultural and religious heritage of many non-Western countries.
... They comprise vivid auditory impressions of words or names, people talking, but also environmental or animal sounds (101). Somatic experiences such as feelings of weightlessness, flying or falling, but also bodily distortions, and more rarely, a sense of presence in the room can occur (102). More rarely and frequently associated with underlying disorders or conditions, such as narcolepsy or altered sleep-wake cycle (92,103), hypnagogic hallucinations can arise from sleep onset REM periods, sharing more similarities with hypnopompic hallucinations, which arise from a mixed state of REM and wake EEG (90). ...
... Dream ideation of REM sleep intruding into wakefulness gives hypnopompic hallucinations a greater emotional load, as unpleasant and frightening experiences, especially when associated with sleep paralysis, where the muscular atonia at EMG extends into wakefulness (85,104). During these episodes, the person feels awake but unable to move, perceives ominous sounds (such as approaching footsteps), feels movement in the bed, and then feels (and/or smells) a person, creature or unspecified entity climbing upon the chest, a smothering sensation, and sometimes even a physical or sexual assault (102). In contrast to simple hypnagogic experiences, these events are typically accepted as vividly real, sometimes taken as assaults by human intruders but often interpreted as occult or metaphysical events (105). ...
Oneiric Stupor (OS) in Agrypnia Excitata represents a peculiar condition characterized by the recurrence of stereotyped gestures such as mimicking daily-life activities associated with the reporting of a dream mentation consisting in a single oneiric scene. It arises in the context of a completely disorganized sleep structure lacking any physiological cyclic organization, thus, going beyond the concept of abnormal dream. However, a proper differential diagnosis of OS, in the complex world of the “disorders of dreaming” can become quite challenging. The aim of this review is to provide useful clinical and videopolygraphic data on OS to differentiate it from other dreaming disorders. Each entity will be clinically evaluated among the areas of dream mentation and abnormal sleep behaviors and its polygraphic features will be analyzed and distinguished from OS.
... Signals from the brainstem to the thalamus project to the cerebral cortex, amygdala, and cingulate cortex. [18] Concomitantly, paralysis occurs due to GABAergic and glycinergic projections originating in the pontine reticular formation and ventromedial region of the medulla on the interneurons of the spinal cord. During SP, wakefulness occurs at the same time as muscle atony. ...
Objectives
The objectives of this study were to determine the prevalence of sleep paralysis (SP) in medical students from the University of Buenos Aires (UBA).
Materials and Methods
An ad hoc questionnaire based on the diagnosis of SP and a demographic survey was electronically presented to students of Internal Medicine at the School of Medicine of the UBA. The respondents answered both questionnaires using Google Forms ® .
Results
The prevalence of SP was 40.7% (95% CI 33.5–47.8). A higher percentage of the respondents (76%) reported experiencing SP-related anxiety. An association between self-perceived quality of sleep and the incidence of SP was found (χ ² : 12.712, P = 0.002). The highest frequency was hypnopompic SP (55.55%), and the highest percentage (55.4%) suffered from SP less than once every 6 months. Most respondents (59.5%) reported having started with SP symptoms after 18 years of age, and the highest percentage (66.2%) had exacerbated their symptoms at college. The frequency of the Incubus phenomenon was 14.5% (95% CI 6.2–23). Most respondents (70.8%) denied the association of SP with religious or paranormal beliefs.
Conclusion
SP is highly prevalent in medical students and is associated with poor sleep habits and perceived poor sleep quality. Clinicians should be aware of this parasomnia to avoid a misdiagnosis of psychosis and inform sufferers of the nature of SP.
... Un episodio puede durar de segundos a varios minutos, aunque bajo este estado las personas son incapaces de hacer movimientos corporales, pueden abrir sus ojos y percibir eventos externos (Hishikawa, 1976;Hishikawa y Shimizu, 1995). Aproximadamente el 30% de los adultos jóvenes ha tenido alguna experiencia de parálisis de sueño (Cheyne, Newby-Clark y Rueffer, 1999b;Fukuda et al., 1998;Spanos et al., 1995). Más allá de una combinación de experiencias sensoriales detalladas y complejas, provenientes de "ataques de íncubos", posesión demoníaca, daño a distancia (mediante el acto mágico de una hechicera que ataca) y abducciones extraterrestres (Baker, 1990;Firestone, 1985;Hufford, 1982;Ness, 1978;Spanos et al., 1993), estas experiencias típicas son aterradoras y las referentes originales del término "pesadilla" o su equivalente en inglés nightmare (Liddon, 1967;Hufford, 1982). ...
Las alucinaciones son percepciones que ocurren en ausencia de estímulos sensoriales correspondientes, pero desde el punto de vista subjetivo del individuo que las experimenta son indistinguibles de la percepción normal. Algo es percibido, pero objetivamente no hay nada para percibir. La alucinación presenta tres características; en primer lugar, existe la convicción de que el fenómeno tiene su origen fuera de uno mismo, hay una falta de control por parte del individuo que in¬tenta distinguir entre las alucinaciones y, por ejemplo, la imaginación; y en tercer lugar, existe una imposibilidad, o por lo menos una dificultad, de alterar o disminuir la experiencia en forma voluntaria.
En buena medida, lo disfuncional de una experiencia alucinatoria dependerá de la respuesta social. Definitivamente, existe diferencia entre una persona que experimenta un delirio místico y una que tiene una experiencia mística. Es diagnóstico psicológico de una persona que dice ver a Jesucristo o a la Virgen María en un santuario mariano no recibe el mismo juicio de integridad mental que una persona que está en un hospital neuropsiquiátrico. Además, individuos que mantienen conversaciones con espíritus son menos propensos a padecer empeoramiento funcional, en tanto y en cuanto, estén rodeados por personas que acepten su experiencia, que si están rodeados por individuos que menosprecian o rechazan sus experiencias.
En conclusión, el autor sostiene que las alucinaciones también pueden ser observadas en personas que no presentan ningún tipo de trastorno psicopatológico. Esta situación lleva a proponer una continuidad del fenómeno alucinatorio entre la normalidad y la patología. Más aún, el modelo de continuidad de la experiencia alucinatoria que se desarrolla en esta obra se basa principalmente en estudios epidemiológicos, y como varía la distribución de estos síntomas en la población general según cómo se mida el fenómeno y explorar otras experiencias perceptuales anómalas. Finalmente, se examina si resulta necesario una nueva palabra para suplir el termino “alucinación” a causa de la clara connotación patológica de la experiencia.
... The risk of 5-hydroxytryptamine syndrome/toxicity will increase if you're conjointly taking different medications that increase serotonin 64 . Examplesstreet drugs like MDMA / ecstasy, certain antidepressants (fluoxetine/paroxetine, different SNRIs such as duloxetine/milnacipran), tryptophan, and others, the chance of serotonin toxicity could be high if you begin or increase the dose for for of for these for For medications for 65 . ...
The brain alternates between wakefulness, nonrapid eye movement (NREM) sleep and rapid eye movement (REM) sleep during sleep. Sleepwalking, sleep terrors, sleepwalking and sleep paralysis are common examples of the behavioral manifestations linked with parasomnias or partial arousals from sleep. Sleep Paralysis is a condition in which someone lying supine position, about drop off to sleep or just upon waking from sleep realize that she/ he unfit to speak or walk or cry out, this may lose many seconds or moments, occupationally longer. The sensation of being paralyzed can be accompanied by various vivid and powerful sensory sensations, such as mentation in visual, aural, and tactile modalities and a distinct sense of presence. People always feel that they've been hanging by someone or wrong, sometimes, cases report this type of problem. They feel that wrong is following, sitting behind them going to be attacked is the condition they feel, in this. Composition reviewed the causes of sleep palsy and what's sleep; many sleep diseases are bandied then. This review discusses details on the management and treatment of sleep paralysis, basic description of sleep paralysis and pathology, etiology, history, epidemiology, and pathogenesis involved in sleep paralysis.
... During REM sleep the EEG expresses with low voltage and desynchronization. In this stage peoples are dreaming (Cheyne et al., 1999). ...
Introduction: Parasomnias are disorders that may appear during sleep with and/or without dreams. To describe them we must take in account a subjective description by the patient and his relatives. Objective measurement of this phenomenology is made with Polysomnography, Electromyography and Holter EKG. Material and Methods: We searched the recent data about parasomnia in the Medline, Pubmed, Google academic databases as also in classic books and reviews. Results: The clinical picture is various from motor and neurological signs to autonomic signs as also sleep related hallucinations. There are more rare presentations with associated disorders due to excretion and involuntary urinary emission during sleep disorders. Parasomnias are often preceded by a traumatic event for the patient and his family members which can be a head trauma or an infection or an intoxication which can be accompanied by psycho vulnerable events. On the other part parasomnias can be themselves a preamble announcing neurodegenerative diseases like Parkinson disease, Lewy Body Dementia or some synucleopathies. Conclusions: The fluctuations of neurotransmitters (Dopamine, Serotonine or Acetylcholine) due to specific neurologic pathology can lead to particular parasomnias, their evolution corresponding to each impairment. The knowledge of accompanying parasomnias of neurologic disorders like those from Parkinson disease helps manage diseases of neurological patients already known with Parkinson's disease or other neurological diseases, leading to increased quality of life for these patients as a result of specialized intervention.
... Both sleep paralysis and hypnagogic states are features commonly associated with narcolepsy (D' Agostino & Limosani, 2010). Appropriately, the anomalous experiences during sleep paralysis have been labelled as hypnagogic and hypnopompic (Cheyne et al., 1999). ...
The hypnagogic state refers to a transitional stage between wakefulness and sleep, in which sensory perceptions can be experienced. In this review, we compile and discuss the recent scientific literature on hypnagogia research regarding the future directions proposed by Schacter (1976; Psychological Bulletin, 83, 452). After a short introduction discussing the terminology used in hypnagogia research and the differentiation of hypnagogic states with other related phenomena, we review the reported prevalence of hypnagogic states. Then, we evaluate the six future directions suggested by Schacter and we propose three further future directions. First, a better understanding of the emotional quality of hypnagogic states is needed. Second, a better understanding of why hypnagogic states occur so frequently in the visual and kinaesthetic modalities is needed. Lastly, a better understanding of the purpose of hypnagogic states is needed. In conclusion, research has made great progress in recent years, and we are one step closer to demystifying the hypnagogic state.
... The highest prevalence in the student population was recorded in Peru namely 55% [52]. In student populations within other countries, the prevalence of SP varies by study, e.g. in Canada, 29 to 41.9% of students have experienced at least one episode of SP [53,54]; in the USA about 25% [55], in Japan from 38.9 to 43% [54,56]; in Nigeria, from 26.2 to 44.2% [57,58]; in Egypt 43% [10], in Kuwait about 29% and in Sudan 30% [59]. ...
Background:
Sleep paralysis (SP) is a transitional dissociative state associated with the REM sleep phase that affects approximately 28.3% of the student population during their lifetime. The reasons for the high prevalence of SP in the student population are not entirely clear. Research indicates possible influencing factors such as the intensification of anxiety symptoms, a tendency to worry, the presence of PTSD symptoms, and behavioral factors such as the consumption of psychoactive substances (caffeine, alcohol, nicotine), sleep deprivations and poor sleep hygiene. The study aimed to assess the prevalence of SP and determine the risk factors for the occurrence of SP in the population of Polish students.
Methods:
The study used a battery online consisting of a set of questionnaires 1) a personal questionnaire, 2) the SP-EPQ, 3) the PCL -5, 4) the STAI-T, 5) the PSWQ. The questionnaire was sent via Facebook to 4500 randomly selected students from different universities in Poland. The questionnaire was completed by 2598 students. To unify the participant sample, people over 35 were excluded from the study (45 students). Ultimately, data from 2553 students were analyzed.
Results:
A total of 33.14% of individuals experienced at least one episode of SP in their lives. The highest odds ratio for SP was associated with: the presence of three or more health problems (OR: 2.3; p = 0.002), the presence of any mental disorder (OR: 1.77; p = 0.002), including mood disorders (OR: 2.07; p = 0.002), suffering from at least one somatic disease (OR: 1.34; p = 0.002), a high level of anxiety as a constant personality trait (OR: 1.20; p = 0.035) and smoking (OR: 1.48; p = 0.0002), alcohol consumption (OR: 1.52; p < 0.0001), physical activity (OR: 1.31; p = 0.001).
Conclusions:
The results of our research indicate that a large proportion of students experienced isolated sleep paralysis. Mental and somatic health problems and lifestyle factors were found to predispose individuals to this disorder. Due to the numerous risk factors for SP, it is necessary to conduct additional research to confirm the impact of these factors and to investigate the mechanisms of their influence on SP.
... Lucid dreams that occur close to the waking state, such as wake-initiated lucid dreams, might be especially prone to incorporate actual bodily sensations or shifts in perspective. Future studies could explore whether other mixed states between wakefulness and REM sleep, including states of sleep paralysis, out-of-body experiences and dissociation [47][48][49], are also related to better balance. ...
Study Objectives
Early research suggests that the vestibular system is implicated in lucid dreaming, e.g., frequent lucid dreamers outperform others on static balance tasks. Further, gravity-themed dreams, such as flying dreams, frequently accompany lucid dreaming. Nonetheless, studies are scarce.
Methods
We attempted to: 1) replicate previous findings using more sensitive static balance measures and 2) extend these findings by examining relationships with dreamed gravity imagery more generally. 131 participants (80 F; Mage=24.1±4.1yrs) estimated lucid dreaming frequency then completed a 5-day home log with ratings for dream lucidity awareness, control, and gravity sensations (flying, falling). They then performed balance tasks on a sensitive force plate, e.g., standing on one or both feet, with eyes open or closed. Center of pressure (CoP) Displacement and CoP Velocity on each trial measured postural stability.
Results
Findings partially support the claim of a vestibular contribution to lucid dreaming. Frequent lucid dreamers displayed better balance (lower CoP Velocity) than did other participants on some trials and lucid dreaming frequency was globally correlated with better balance (lower CoP Velocity). Lower CoP Velocity was related to flying sensations in men’s dreams and with more dream control in women’s dreams. However, body height—possibly due to its relationship to sex—and levels of sleepiness confound some of these effects.
Conclusion
While findings only provide a partial replication of previous work, they nonetheless support an emerging view that the vestibular system underlies basic attributes of bodily self-consciousness, such as feelings of self-agency and self-location, whether such consciousness occurs during wakefulness or dreaming.
... The dream world often makes intentions harder to achieve. This evidence is used to support the threat simulation theory of dreaming, according to which dreams let us practise responding to threatening scenarios (Cheyne 2000;Cheyne et al. 1999;Revonsuo et al. 2015b). A fluke could occur if the dreamer forms an intention to sink the ball in the far-right pocket, they shoot and fail, but the ball rebounds and sinks, to their surprise, in the near left pocket. ...
Although the sense of agency is often reduced if not absent in dreams, our agentive dream experiences can at times be similar to or enhanced compared to waking. The sense of agency displayed in dreams is perplexing as we are mostly shut off from real stimulus whilst asleep. Theories of waking sense of agency, in particular, comparator and holistic models, are analysed in order to argue that despite the isolation from the real environment, these models can help account for dream experience. The dreamer might feel an increased sense of control of their dream bodies and a sense that they can directly control elements of the dream world. Such experiences may at times be caused by superstitious or delusional thinking due to altered cognition and changes to the sleeping brain. Here it is argued that some such experiences are akin to specific waking delusions, such as delusions of grandeur, with similar cognitive features. However, other instances of increased sense of agency in dreaming appear to be sui generis and nothing like what we experience when awake. Lucid control dreams, in which the dreamer realises that they are dreaming and that they can control the dream environment, are examples of such an experience although further nuance is required to account for their specific cognitive attributes. Future empirical research should focus on controlled dream reporting conditions in order to clarify the types of experience that occur and determine the relevant cognitive mechanisms that relate to each type.
... Debido a la distancia que toman ciertos aspectos clínicos frente a la temática especializada en esta investigación, no se ve oportuno adentrarnos profundamente en el contexto médico. No obstante, mencionar que hay numerosos estudios en el campo neurológico que estudian en profundidad las características neurobiológicas de las alucinaciones en la parálisis del sueño y la modulación cerebral que acompaña a estas experiencias perceptivas (J. A. Cheyne et al., 1999; J. Allan Cheyne & Girard, 2007;D'Agostino & Limosani, 2016;Manford & Andermann, 1998;Manni et al., 2002). En las características cualitativas de la experiencia, se clasifican de forma esquemática algunas de las experiencias y vivencias sensoriales producto de las alucinaciones. ...
During this research, called Prototypes and archetypes of the representation of sleep paralysis: an approach from art, we analyzed, as its title indicates, the different artistic prototypes and archetypes that have emerged around a neurological sleep disorder known as sleep paralysis. This parasomnia takes place during the transition from sleep to wakefulness, responding to common symptoms that cause great suffering and fear to those afflicted by it, primarily through visual sensory hallucinations.
Due to the limited and scarce information on this sleep disorder in the field of artistic research, a medical approach has been followed in the first and second chapters, accompanied by a discussion of the relevant psychological aspects, which will enable a better understanding of the anthropological field that surrounds it. This allows us to enter in the third chapter, where the cultural evolution of this parasomnia in the anthropological context is investigated through the examination of the mythology surrounding the incubus and the succubus, both of which are figures that are frequently associated with sleep paralysis. Their respective interpretation and interiorization as real beings will provide, through the association of ideas and the collective imagination, different social behavioral values to people regarding their experience with sleep paralysis. In the fourth chapter, an exhaustive analysis of prototypes and archetypes arising from the artistic representation of sleep paralysis is presented, focusing on the study of the work The Nightmare (1781) by Henry Füssli. A categorization and methodological chronology of different works ranging from the 18th century to the present day is discovered, which allows us to understand and study their analogous corresponding representation in art. In the fifth chapter, it is provided a reflection On the artistic representation and interpretation of different concepts associated with sleep paralysis, such as identity, memory and the emotion of fear, which has forwarded our understanding of this sleep disorder. At the same time, a study specifically designed for this project involved the collection of testimonies of people who have experienced sleep paralysis, in order to study their visual patterns in hallucinations from their descriptions. In the sixth and last chapter, a new perspective on the representation of sleep paralysis is proposed through the creation of subjective visual works (based on the testimonies) using photographic techniques.
The methodology used to undertake this research involved the study and analysis of ancient medical and cultural treatises, such as the Persian manuscript Hidayat by Akhawayni Bohkari from the 10th century, The Discoverie of Witchcraft (1584) by Reginald Scot, the story The Night-Mare (1664) by Isbrand Van Diermerbroeck, the essay An essay on the incubus, or nightmare (1753) by John Bond and The Nightmare (1931) by Ernest Jones, among others. In additioninterviews were taken from contemporary artists who currently represent sleep paralysis very similar and were assembled in a compendium. Furthermore, an analytical and statistical study was also carried out, based on interviews of people who have suffered from this sleep disorder accompanied by a collection of written testimonies submitted through a web page created specifically for this artistic study.
One of the main objectives was to develop a codified study of the myths and legends in different cultures and countries, and to understand their symbolic representation based on their popular imagery and the existing tradition in the category of the monstrous and the figure of the incubus in art. Specifically, we tracked the above mentioned work The Nightmare by Füssli, a work whose influence pertains to this day, being the most representative prototype and archetype of sleep paralysis. These research outputs will allow us to reflect on, to recreate and to question the existing representation of sleep paralysis in art until our days. The final objective is to approach the subjective representation of the experience of sleep paralysis, breaking with the prototype and archetype created over the years. To this end, new patterns of representation will be proposed through the author`s artistic creation based on the collected testimonies, in order to create a visual guide that serves as a means of understanding a society that has no prior experience with sleep paralysis.
As a final conclusion, the interdisciplinary nature of this research has allowed us to understand the mythology and beliefs associated with sleep paralysis, which enables the identification and designation of possible prototypes and archetypes in the artistic representation of this parasomnia, marked by a powerful collective imagination. The artistic work presented here has created novel prototypes and archetypes of sleep paralysis, which greatly advances our understanding of this experience. As it is shown, this work is considerably better understood when is accompanied by the description of testimonies, as it connects a communication code between the text and the image. Nevertheless, despite the fact that a new proposal for the representation of sleep paralysis in art is emerging, the timeless value of the representation of Füssli’s The Nightmare is confirmed here. With this study, and with the resulting artistic works, we are able to approximate the experience of this parasomnia to a public that was unaware of it, which also reveals how the imagination operates on a collective and personal level, since it is built on each individual with components that are inherited culturally and transmitted and expressed through art.
... The essential factors of IM efficiency are hypnopompic hallucinations, which are the opposite of hypnogogic hallucinations. Hypnopompic hallucinations are sensory or emotional perceptions that occur during the process of awakening and don't have a real physical basis (Cheyne et al., 1999). They can be very stable and might be considered as remnants of REM sleep. ...
Most people experience lucid dreams (LDs), which are dreams in which the dreamer is conscious and able to perceive vivid perceptions. There are many ways to induce LDs, but their levels of efficiency are far from satisfactory. In this study, we analyze the efficiency of an LD method that was tested in commercial events with hundreds of groups over 12 years. The main feature of the method is that hypnopompic hallucinations are induced that allow an LD plot to start directly from the bedroom upon awakening, which makes the LD feel like an out-of-body experience. This method originated from the Tibetan dream yoga tradition and has been heavily modified according to a strict algorithm of specific actions. Data from 449 people, mostly newbies, who tried this method over the course of two nights indicated that 484 attempts were successful. This method might help ordinary LD enthusiasts to get efficient practice, as well as more research opportunities for studying lucid dreaming and the human brain.
... 6 According to Cheyne, 7 fear arises mostly from the reaction to an inability to move or the hallucinatory content. Approximately 70% of SP episodes are accompanied by hallucinations, 8,9 although some studies found theirsimultaneous occurrence only in 33%.10 Mostly, we distinguish 3 types of hallucinationsintruders, incubus and ...
Sleep paralysis is atemporary disorder where the suffering person is unable to talk or move the body parts and also experience a temporary breathlessness. Patient may complaint like an evil is sitting on them and making them immovable. It occurred due to the sleep disturbances during sleep while drop off to a sleep or during awaking from a sleep. Sleep paralysis may last for few seconds tominutes mostly. The main common causes for sleep paralysis are stress, sudden disturbances in sleep etc. The very common symptoms are anxiety, hallucination or paralysis which is temporary. In this article the causes and treatment for sleep paralysis are discussed."
... These often take the form of uncanny "ghost-like" experiences and evoke extreme fear reactions (Jalal, 2018). Cheyne places these into three categories: intruder (sense of evil presence and multi-sensory hallucinations of intruder), incubus (feeling of pressure on the chest, suffocation, and physical pain), and vestibular-motor (feature illusorymovement and out-of-body experiences) (Cheyne et al., 1999b;Cheyne, 2003). Intruder and incubus hallucinations typically cooccur and are accompanied by fear, whereas vestibular-motor hallucinations are more positive (Cheyne, 2003). ...
... Sleep has been associated with out of body experiences (Cheyne et al., 1999;Maquet et al., 1996). More specifically, the hypnagogic and hypnopompic experiences are accompanying sleep paralysis and include supernatural nocturnal assaults and paranormal experiences and are closely associated with Rapid Eye Movement (REM) sleep. ...
Body ownership reflects our ability to recognise our body at a certain location, enabling us to interact with the world. Emotion has a strong impact on memory and body ownership; interestingly, skin temperature may at least in part mediate this impact. Previous studies have found that out-of-body experiences (OBE) impair memory encoding and cause skin temperature to drop. In the present study a new method for inducing OBE was designed and their impact on a different stage and type of memory processing (emotional memory consolidation) and on skin temperature was investigated. In our experiment, we presented three types of emotional pictures (neutral, pleasant, unpleasant) before inducing OBE and testing our participants’ recognition memory in a retrieval session. Throughout the whole experiment, both neck and hand skin temperature were measured using iButtons. Participants’ performance was calculated using d-prime and statistical analyses included one-way ANOVA, probing the relationship between the score on the OBE questionnaire, performance and skin temperature; we also compared the differences between the experimental and a control group. Results showed that OBE favour emotional memory consolidation and cause a temperature increase, supporting the embodied cognition theory as proposed by Anderson (2003). Future studies should expand our findings, to rule out that participants experiencing OBE could have a better memory at baseline or that temperature could be increased due to other reasons.
... For a review on further historic and more recent studies into the neurophysiology of sleep paralysis, see Stefani et al. [6]). For the co-occurrence of sleep paralysis together with hypnagogic or hypnopompic hallucinations, a three-factor structural model (intruder, incubus, and unusual bodily experience) has been proposed [48]. Intruder consists of sensed presence, fear, and auditory and visual hallucinations. ...
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.
... People's familiarity with pain and its causes (i.e., emotional vividness of pain, quick pain appearance; Nagi et al., 2019), the existence of psychosomatic pain (Tyrer, 2006), and the theoretical possibility of PLD (Zadra et al., 1998) make pain a fitting concept to examine to study the influence of LD on psychophysiological processes. Though studies on hypnopompic hallucinations and their nature (Cheyne, Rueffer, & Newby-Clark, 1999) make sense of PLDW, there is no evidence suggesting that it is possible to control hypnopompic hallucinations in such a way. ...
During lucid dreaming, people experience vivid perceptions and emotions that may have a psychophysiological impact after the person awakens. The goal of this research is to test whether it is possible to create pain during lucid dreaming and maintain it upon awakening. For this study, 151 volunteers completed a task in which they needed to achieve pain during lucid dreams (LD) and then wake up. They then checked whether the pain from the dream remained after they awoke and, if so, they reported how long the pain lasted. Of the participants, 74% experienced pain during LD and 28% of them continued feeling the pain after waking. Our results may lead to new pain treatments and a better understanding of the nature of pain, LD, and hypnopompic hallucinations.
... SP is characterized by the inability to move or speak upon awakening or while falling asleep [17,18] and lasts no longer than a couple of minutes [19,20]. SP occurs during REM sleep [21]. ...
During REM sleep we normally experience dreams. However, there are other less common REM sleep phenomena, like lucid dreaming (LD), false awakening (FA), sleep paralysis (SP), and out of body experiences (OBE). LD occurs when one is conscious during dreaming, and FA occurs when one is dreaming but believes that has woken up. SP is characterized by skeletal muscle atonia and occurs mainly during awakening or falling asleep. OBE is the subjective sensation of ‘leaving the physical body’. Since all these phenomena happen during REM sleep, their frequency is probably connected. The goal of this research is to explore how these phenomena are connected to each other in terms of frequency. We surveyed 974 people on the streets of Moscow and found significant correlations between the phenomena. Of those surveyed, 88% have experienced at least one of the phenomena of interest (i.e., LD, OBE, FA, and SP), which appeared to be closely correlated to each other. Furthermore, 43% of respondents stated that they often experience at least one of these phenomena. We found that the recurrence of these phenomena correlated with sleep duration and dream recall frequency. The results of the survey provide better understanding of the nature of REM sleep dissociative phenomena.
Cross-correlations between REM sleep dissociated phenomena, like lucid dreaming, sleep paralysis, out-of-body experiences, and false awakening, revealed by a survey
... "Some people have such deep visions that they feel like someone is trying to strangle or suffocate them. I see someone coming into their room, and they are unable to move '' (Cheyne, 1999). The concept of paranormal comes and can exist only in the human imagination because people's belief in exorcism, possession, paranormal events appeared after the television broadcast of a film called The Exorcist (Sersch, 2013). ...
... 6 According to Cheyne, 7 fear arises mostly from the reaction to an inability to move or the hallucinatory content. Approximately 70% of SP episodes are accompanied by hallucinations, 8,9 although some studies found theirsimultaneous occurrence only in 33%.10 Mostly, we distinguish 3 types of hallucinationsintruders, incubus and ...
This report presents the personal experiences of three individuals who ingested iboga or ibogaine in different contexts and for different reasons. Narrative analysis reveals a connection with previously identified phenomenological categories of experience, however demonstrating a wide variability. Most notably, each of these interviewees reported a distinct impression of transpersonal communication, either with “iboga/ine” or with visions of others encountered in the oneirogenic experience. This relates with a sense of transpersonal presence that is mentioned elsewhere in literature describing waking REM experiences, such as sleep paralysis. Within these cases, a sense of transpersonal intersubjectivity appears to contribute a sense of ontological realism and meaningfulness of the experiences. Similar deep engagement with narrative reports may better inform future research, as well as ibogaine‐assisted therapies.
The author examines the concept of “sleep paralysis” from the point of view of biology and folk culture. The key components of this concept, highlighted by various authors, touches on the main problems related to this concept, including the relationship between biological and cultural in the context of sleep paralysis, are presented. In addition, the work describes possible interpretations of sleep paralysis, mythological characters associated with it in the folklore of different peoples of the world, and folklore genres in which it is reflected. Moreover, the article contains examples of narratives about cases of sleep paralysis in folklore; outside the cultural tradition, where mythological characters associated with sleep paralysis are known; as well as an example of the appearance of mythological characters connected with manifestations of sleep paralysis not in a mythological text, but in other folklore genres.
Sleep paralysis is a period of time at sleep onset or upon awakening from sleep during which voluntary muscle movements are inhibited. Ocular and respiratory movements remain unaltered and perception of the immediate environment is clear. A common symptom of narcolepsy, the term isolated sleep paralysis is preferred when sleep paralysis is present in the absence of a narcolepsy diagnosis. The presence of frequent episodes is termed recurrent isolated sleep paralysis. Alongside the paralysis, episodes are accompanied by a range of bizarre and often terrifying hallucinations.
Sleep paralysis, as it is known today, was one of the most remarked-upon maladies in premodern medicine. The feeling of being choked during sleep was usually seen by physicians as being caused by an abundance of melancholic humors. Others interpreted the experience as a supernatural attack. However, the distinctions between medical and “superstitious” remedies against nightmares were rarely so clear cut, especially given the belief that demons were able to manipulate the bodily humors. In this article I will chart the various substances—plant and stone—that were traditionally believed to assuage the symptoms of the nightmare. I will examine how “hot” herbs, such as peony, and minerals with occult heating properties, such as gagate, could rebalance the dangerously cold and heavy vapors that provoked a nightmare attack. It will be seen that even seemingly “magical” apotropaic practices were entirely rational within the milieu of humoral theory.
We investigated sleep paralysis (SP) with an online questionnaire. Our sample consisted of 380 participants who experienced at least one SP. In this paper, we present the relation of SP to extraordinary experiences, paranormal beliefs , and absorption. We used a German questionnaire, Fragebogen zur Phänomenologie außergewöhnlicher Erfahrungen (PAGE-R-II), to assess the extent to which people with SP have had other extraordinary experiences, a German translation of the Belief in the Supernatural Scale (BitSS), and a German version of the Tellegen Absorption Scale (TAS). Our hypotheses regarding a positive correlation between the frequency of SP and certain forms of extraordinary experiences, paranomal/ supernatural beliefs, and absorption were only partially confirmed. We found an expected significant correlation between the frequency of SP and the expression on the PAGE dimensions "Dissociation" and "External," but not between SP frequency and the other scales. The group (55%) reporting paranormal experiences during SP had highly significant higher mean scores on the PAGE, BitSS, and TAS. There were also significant correlations between the applied scales and specific hallucinatory perceptions and emotions, which leads us to believe that two main types of experiencing SP may exist: one mainly connected with typical negative emotions and a more external focus of experience, and another characterized by positive emotions and more internally experienced perceptions. This hypothesis requires further investigations. Highlights • The frequency of sleep paralysis (SP) episodes is highly correlated with the frequency of other specific extraordinary experiences outside of SP.
Background: Sleep paralysis (SP) is a transit dissociative state associated with the REM sleep phase that affects approximately 28.3% of the student population during their lifetime. The reasons for the high prevalence of SP in the student population are not entirely clear. Research indicates possible influencing factors such as the intensification of anxiety symptoms, a tendency to worry, the presence of PTSD symptoms, and behavioral factors such as the consumption of psychoactive substances (caffeine, alcohol, nicotine) and poor sleep hygiene. The study aimed to assess the prevalence of SP and its risk factors in the Polish student population.
Methods: The study used a battery online consisting of a set of questionnaires (a personal questionnaire, 2) the SP-EPQ, 3) the PCL -5, 4) the STAI-T, 5) the PSWQ). The questionnaire was sent via Facebook to 4500 randomly selected students from different universities in Poland. The questionnaire was completed by 2598 students. To unify the participant sample, people over 35 were excluded from the study (45 students). Ultimately, data from 2553 students were analyzed.
Results: A total of 33.14% of individuals experienced at least one episode of SP in their lives. The highest odds ratio for SP was associated with: the presence of three or more health problems (OR: 2.3; p = 0.002), the presence of any mental disorder (OR: 1.77; p = 0.002), including mood disorders (OR: 2.07 ; p = 0.002), suffering from at least one somatic disorder (OR: 1.34; p = 0.002), a high level of anxiety as a constant personality trait (OR: 1.20; p = 0.035) and smoking (OR: 1.48; p = 0.0002), alcohol consumption (OR: 1.52; p <0.0001), physical activity (OR: 1.31; p = 0.001).
Conclusions: The results of our research indicate that a large proportion of students experienced isolated sleep paralysis. Mental and somatic health problems and lifestyle factors were found to predispose to this disorder. Due to the numerous risk factors for SP, it is necessary to conduct additional research to confirm the impact of these factors and to investigate the mechanisms of their influence on SP.
Since antiquity, the mystery around sleep and its disorders, particularly parasomnias, has stimulated the development of superstitions, myths and tales. In Modern Age, some physicians had tried to explain these phenomena as neuropsychiatric and organic diseases. The definitive acknowledgment of parasomnias as organic disorders occurred only during the twentieth century when sleep medicine became a scientific discipline. Recently, the development of the modern polysomnography has allowed identifying new parasomnias, so the history of parasomnias does not seem to end in the first part of the last century, but new sleep disorders could be identified in future years.
Sleep paralysis (SP) is the inability to
conduct voluntary movement either at
sleep onset or upon awakening. Half of
these episodes are accompanied by
hallucinatory experiences. This study
explored the predictive value of
catastrophic thinking patterns and a
tendency to use of supernatural beliefs as
explanations for these episodes in the
hallucinatory experiences and level of postepisode distress reported in young adults
experiencing the phenomenon. A crosssectional design was employed. 289
undergraduate students completed a series
of online self-report measures. Multiple
regression analysis revealed that
catastrophic thinking and age explained
19% of the variance in frequency of
hallucinatory experiences reported.
Separate regression analysis revealed that
catastrophic thinking, gender, depression
and hypnagogic and hypnopompic
hallucinations explained 43% of the
variance related to post-episode distress.
Hallucinatory experiences during sleep
paralysis may be exacerbated via a
catastrophic thinking style and this may
subsequently heighten post-episode
distress. Sleep paralysis post-episode
distress should be viewed from a
multidimensional perspective and sleep
paralysis treatment may benefit from a
CLINICAL PSYCHOLOGY TODAY VOL 5(2)
DECEMBER 2021 22
psychologically informed approach. Future
research should replicate these findings in a
clinical population.
We present some key findings from an online survey on isolated sleep paralysis. The aim of our study was to get a differentiated picture of the correlation between the frequency of sleep paralysis and several phenomena (symptoms, experiences) as well as factors correlated with these phenomena. We also investigated the role of gender in relation to the experience of sleep paralysis. We used a selected sample of subjects who had had at least one sleep paralysis experience, with a total of 380 subjects. On average, the participants experienced 10–20 sleep paralysis episodes. We found high and expected positive correlations between the frequency of sleep paralysis experiences and the amount of phenomena, emotions, and perceived shapes and forms experienced during sleep paralysis. An increased frequency of sleep paralysis also appears to lead to habituation and de-dramatization in some affected individuals. Interestingly, significant correlations are missing where one would have suspected them based on the previous hypotheses. Neither self-perceived general stress nor poor sleep hygiene appeared to influence the frequency of sleep paralysis. We found highly significant gender differences in some items. Women reported more experienced phenomena and emotions overall, had more frequent sleep paralysis experiences of the intruder and incubus type, and were significantly more likely to perceive concrete forms such as human figures or people they know. They were also more likely than men to report experiencing fearful emotions, especially the fear of going crazy. Most of these findings were based on exploratory questions; they require replication for validation.
Part II began by asking whether it was appropriate for NDE subjects to conclude that ND/OBE are completely unrelated to dreams. Ordinary daytime living consciousness comprises three state-boundaries: wakefulness, and the two modes of natural sleep: rapid-eye movement (REM) and non-REM (NREM) sleep. Essentially, these are mutually controlled by the “cerebral monoaminergic fountain” (Fig. 5.1) between acetyl-choline, serotonin, dopamine, and adrenaline (nor-epinephrine) secretion. Reversion from one state-boundary to another can be almost instantaneous as we all recognise if having overslept, that crisis being immediately followed by the rapid reversion to attention required in meeting immediate responsibilities. Although subjects while sleeping may seem to be “unconscious”, their brains are considerably active, especially during the REM sleep mode. REM sleep-mode is, surprisingly, an example of intense cortical arousal following secretion of nor-adrenaline and serotonin (secreted from midbrain/pontine neurones), during which physical parameters (pulse, temperature and blood pressure, and the EEG) suggest that subjects are actually awake. Sleeping itself comprises several recurring cycles of NREM and REM sleep. Dreaming occurs during both, but more so within successive REM periods, while NREM dreams are generally more abstract in nature. Above, the striking parallels between various forms of normal dreaming and ND/OBE phenomenology were brought to light ( Addendum II.1).
Background
Few studies have investigated hallucinations that occur at the onset/offset of sleep (called hypnagogic/hypnopompic hallucinations; HHHs), despite the fact that their prevalence in the general population is reported to be higher than the prevalence of daytime hallucinations. We utilized data from an epidemiological study to explore the prevalence of HHHs in various modalities. We also investigated phenomenological differences between sleep-related (HHHs) and daytime hallucinations in the auditory modality. We hypothesized that individuals with only HHHs would not differ from controls on a range of mental health and wellbeing measures, but that if they occur together with daytime hallucinations will pose a greater burden on the individual experiencing them. We also hypothesize that HHHs are qualitatively different (i.e. less severe) from daytime hallucinations.
Methods
This study utilized data from a cross-sectional epidemiological study on the prevalence of hallucinations in the Norwegian general population. The sample (n = 2533) was divided into a control group without hallucinations (n = 2303), a group only experiencing sleep-related hallucinations (n = 62), a group only experiencing daytime hallucinations (n = 57), and a group experiencing both sleep-related as well as daytime hallucinations (n = 111). Prevalence rates were calculated and groups were compared using analyses of variance and chi-square tests where applicable.
Results
The prevalence for HHHs in the auditory domain was found to be 6.8%, whereas 12.3% reported multimodal HHHs, and 32.2% indicated out-of-body experiences at the onset/offset of sleep. Group comparisons of hallucinations in the auditory modality showed that individuals that experienced only auditory HHHs scored significantly (p < 0.05) lower than those who also experienced daytime auditory hallucinations on a range of variables including mental health, anxiety, childhood happiness, and wellbeing. In addition, individuals with only auditory HHHs reported significantly (p < 0.05) less frequent hallucinations, less disturbing hallucinations, more neutral (in terms of content) hallucinations, hallucinations with less influence over their behavior, and less hallucination-related interference with social life compared to those individuals that experience daytime hallucinations. We also found that purely auditory HHHs had a significantly higher age of first onset of hallucinations than the purely daytime and the combined daytime and auditory HHHs groups (28.2 years>20.9 > 19.1).
Conclusions
Sleep-related hallucinations are common experiences in the general population, with the auditory modality being the least common. They occur mostly in combination with daytime hallucinations. However, some individuals (2.4%) experience only (auditory) sleep-related hallucinations and this group can be seen as more closely related, on a range of health-related factors, to non-hallucinating individuals than individuals who experience daytime hallucinations. Finally, there is a clear need for more research in this field, and ideas for future studies are presented.
About 35–45% of refugees and asylum seekers in Denmark suffer from PTSD, anxiety and/or depression, and a growing number of Muslim refugees encounter Danish psychiatry, e.g., at the outpatient mental health facility Competence Centre for Transcultural Psychiatry (CTP) in Copenhagen (Turrini et al. in Journal of Mental Health Systems 11:51, 2017). The intercultural encounter between refugees from Muslim countries and Western psychiatry reveals differences in the conceptualization of mental illness. Jinn beliefs (beliefs in spirits in Islam) can play a substantial role in some Muslim patients’ conceptualization of distress, while Western mental health professionals rarely incorporate religious beliefs in their understanding of mental illness. The mismatch in explanatory models is grounded in divergent ontological worldviews and can lead to misdiagnosis and delayed treatment. This article stresses the need for incorporating both cultural and psychiatric perspectives to understand distress attributed to jinn influence by Muslim patients. First, the article introduces the Islamic notion of jinn. Then, it addresses the subject of possession from a psychiatric and anthropological perspective. Additionally, an example of a phenomenon often attributed to jinn will also be presented from a psychiatric and cultural perspective. Second, the article presents three cases in which patients from the CTP use jinn beliefs as an explanatory model for (part of) their afflictions.
Sleep paralysis is a curious condition where the paralyzed person may hallucinate terrifying ghosts. These hypnogogic and hypnopompic visions are common worldwide. They often entail seeing and sensing shadow beings; although hallucinating full-fledged figures (e.g., cat-like creatures and witches) are not uncommon. In this paper, I propose a neuroscientific account (building on previous work) for why people see ghosts during sleep paralysis and why these tend to manifest as faceless shadows. This novel venture considers the distinct computational styles of the right and left hemisphere and their functional specializations vis-à-vis florid intruder hallucinations and out-of-body experiences (OBEs) during these dream-like states. Additionally, I provide a brain-based explanation for dissociative phenomena common during sleep paralysis. Specifically, I posit that these ghost hallucinations and OBEs are chiefly mediated by activity in key regions in the right hemisphere; and outline how the functional organization of the visual system (evoking concepts like surface interpolation) and its economizing nature (i.e., proclivity to minimize computational load and take short-cuts) can explain faceless humanoid-shadows and sensed presence hallucinations during sleep paralysis; and how the hypothalamus and anterior cingulate may be implicated during related dissociative states. Ultimately empirical research must shed light on the validity of this account. If this hypothesis is correct, patients with right hemisphere damage (i.e., in implicated areas) should be less likely to hallucinate ghosts during sleep paralysis; i.e., compared to those with intact hemispheres or damage to the left only. It may also be possible to temporarily disable right hemisphere functions during sleep paralysis using transcranial magnetic stimulation. Accordingly, this procedure should eradicate sleep paralysis ghost hallucinations.
Purpose of the review:
Recent studies have increased our understanding of the biochemical and structural bases of visual hallucinations in patients with a variety of underlying causes.
Recent findings:
Visual hallucinations may be related to disruption of functional connectivity networks, with underlying biochemical dysfunction such as decreased in cholinergic activity. Structural abnormalities in primary and higher order visual processing areas also have been found in patients with visual hallucinations. The occurrence of visual hallucinations after vision loss, the Charles Bonnet syndrome, may have more functional similarity to psychiatric and neurodegenerative causes than previously suspected despite retained insight into the unreal nature of the phenomena.
Summary:
Visual hallucinations are common, and patients may not report them if specific inquiries are not made. Presence or absence of hallucinations may be of diagnostic and therapeutic importance, especially in patients with neurodegenerative conditions that have overlapping features. Treatment of visual hallucinations remains challenging and must be tailored to each patient based on the underlying cause and comorbid conditions.
This chapter looks at the ways that individual conceptions of reality can become shared cultural elements. Instead of relying on shared categories, people often communicate across differences by using empathy, giving anthropologists a new perspective on processes of cultural change. Ben and his family believe that, over the years, he was attacked by several ghosts. The behavior of these ghosts has strayed from how most Thais expect them to behave. This is not a problem when it comes to understanding Ben’s ghost stories, however; instead of trying to fit Ben’s idiosyncratic stories into preexisting models about ghosts, his friends and family ask themselves, “Is this something that could happen to a person?” That is, they engage in empathic perspective taking to solve the problems his stories present, experimentally putting themselves in his shoes and thinking about Ben’s nature as a human being, rather than referring to preexisting cultural categories.
We explore the application of a wide range of sensory stimulation technologies to the area of sleep and dream engineering. We begin by emphasizing the causal role of the body in dream generation, and describe a circuitry between the sleeping body and the dreaming mind. We suggest that nearly any sensory stimuli has potential for modulating experience in sleep. Considering other areas that might afford tools for engineering sensory content in simulated worlds, we turn to Virtual Reality (VR). We outline a collection of relevant VR technologies, including devices engineered to stimulate haptic, temperature, vestibular, olfactory, and auditory sensations. We believe these technologies, which have been developed for high mobility and low cost, can be translated to the field of dream engineering. We close by discussing possible future directions in this field and the ethics of a world in which targeted dream direction and sleep manipulation are feasible.
The sleep paralysis nightmare has been reported from antiquity to modernity across manifold cultures. Many people who experience nocturnal assaults by dark entities, demons, hags, or incubi during sleep paralysis ascribe them to evil spirits with varying degrees of malevolence. The majority report the episodes as terrifying, mysterious, and uncanny. Known in the neurocognitive literature as “isolated sleep paralysis” or “sleep paralysis with hypnagogic and hypnopompic hallucinations,” the phenomenon is fascinating to researchers across disciplines because it occurs when we are both asleep and awake, presenting fundamental questions on the subject of conscious experiences in sleep.
This article considers the nightmare of sleep paralysis to be an archetypal psychic process akin to Jung’s night sea journey and having correspondence to the wrathful deities presented in the Tibetan Book of the Dead. With a Jungian perspective directed at artwork created by a person who has experienced sleep paralysis, archetypal imagery emerges and reveals elements missing from conscious view. Utilizing the interpretive frameworks of Jungian-oriented depth psychology and Tibetan Buddhist psychology, this universally experienced nightmare of terror can also be undergone as a dream of transformation with potential for psychological and spiritual growth.
This article explores the nature of psychedelically induced anomalous experiences for what they reveal regarding the nature of “expanded consciousness” and its implications for humanistic and transpersonal psychology, parapsychology, and the psychology and underlying neuroscience of such experiences. Taking a multidisciplinary approach, this essay reviews the nature of 10 transpersonal or parapsychological experiences that commonly occur spontaneously and in relation to the use of psychedelic substances, namely synesthesia, extradimensional percepts, out-of-body experiences, near-death experiences, entity encounters, alien abduction, sleep paralysis, interspecies communication, possession, and psi (telepathy, precognition, and clairvoyance and psychokinesis).
Resumen
Los años recientes han visto un interés creciente en la experiencia alucinatoria, incluidas investigaciones de su prevalencia fenomenológica y carácter tanto en poblaciones patológicas como normales (predispuestas). Investigamos la multidimensionalidad de las experiencias alucinatorias en 265 sujetos de la población normal que rellenaron una versión modificada de la Escala de Alucinaciones de Launay-Slade. Se realizó análisis de componentes principales sobre los datos. Se obtuvieron cuatro factores que saturaban en elementos que reflejaban (1) experiencias alucinatorias relacionadas con el sueño, (2) ensoñaciones diurnas vividas, (3) pensamientos intrusos o carácter real del pensamiento y (4) alucinaciones auditivas. Los resultados ofrecen nuevos datos de la multidimensionalidad de la disposición alucinatoria en la población normal. Se analizan direcciones para investigaciones futuras en la predisposición alucinatoria.
In Japan, there is a set of experiences called kanashibari, which is symptomatically identical to sleep paralysis with or without hypnagogic hallucinations. In a former study (Fukuda et al., 1987a), the author and co-workers have investigated this phenomenon by a questionnaire method and have found that among the normal population the phenomenon is apparently more common than has been usually appreciated. The author conducted this study to confirm the coincidence between kanashibari and sleep paralysis polygraphically, and then to investigate the characteristics of sleep onset REM periods (SOREMPs) with the kanashibari phenomenon. The two subjects with frequent experiences of kanashibari and the other two subjects without the experience slept under an altered sleep schedule. The schedule, which consisted of reversal of usual sleep-wakefulness cycle and sleep interruption. One of the subjects reported that she had been about to have a kanashibari attack during the experiment. During the REM sleep, when the subject was probably about to experience kanashibari, abundant alpha EEG and an elevated heart rate were observed. The author suggests the relations between a higher consciousness level in kanashibari and the abundant alpha EEG, and between emotional components of the phenomenon and the increased heart rate.
Sleep paralysis is an essentially rare condition of unknown aetiology associated with both the narcolepsy-cataplexy syndrome and with psychological dissociative experiences. This supposedly rare condition seems to be well known to Alaska Eskimos, having Eskimo names, a traditional cause, and a method for treatment. Pertinent literature is reviewed on sleep paralysis, Eskimo personality dynamics, in particular the use of hysterical mechanisms, and traditional explanations for phenomena of this type including literature on shamanism. Suggestions are made for the clinical approach to patients in the cross-cultural setting.
There have been tremendous advances in our knowledge of the neurobiological basis of human anxiety and fear. This review seeks to highlight how specific neuronal circuits, neural mechanisms, and neuromod ulators may play a critical role in anxiety and fear states. It focuses on several brain structures, including the amygdala, locus coeruleus, hippocampus, and various cortical regions and the functional interactions among brain noradrenergic (NE), corticotropin releasing hormone (CRH), and the hypothalamic pituitary adrenal axis (HPA). Particular attention is directed toward results that can lead to a better understanding of the constellation of the symptoms associated with two of the more severe anxiety disorders, panic disorder and posttraumatic stress disorder (PTSD), the persistence of traumatic memories, and the effects of stress, particularly early life adverse experiences, on brain function and clinical outcome. NEUROSCIENTIST 4: 35-44, 1998
Assessments of anterior cingulate cortex in experimental animals and humans have led to unifying theories of its structural organization and contributions to mammalian behaviour The anterior cingulate cortex forms a large region around the rostrum of the corpus callosum that is termed the anterior executive region. This region has numerous projections into motor systems, however since these projections originate from different parts of anterior cingulate cortex and because functional studies have shown that it does not have a uniform contribution to brain functions, the anterior executive region is further subdivided into 'affect' and 'cognition' components. The affect division includes areas 25, 33 and rostral area 24, and has extensive connections with the amygdala and periaqueductal grey, and parts of it project to autonomic brainstem motor nuclei. In addition to regulating autonomic and endocrine functions, it is involved in conditioned emotional learning, vocalizations associated with expressing internal states, assessments of motivational content and assigning emotional valence to internal and external stimuli, and maternal-infant interactions. The cognition divi sion includes caudal areas 24' and 32', the cingulate motor areas in the cingulate sulcus and nociceptive cortex. The cingulate motor areas project to the spinal cord and red nucleus and have premotor functions, while the nociceptive area is engaged in both response selection and cognitively demanding information processing. The cingulate epilepsy syndrome provides important support of experimental animal and human functional imaging studies for the role of anterior cingulate cortex in movement affect and social behaviours. Excessive cingulate activity in cases with seizures confirmed in anterior cingulate cortex with subdural electrode recordings, can impair consciousness alter affective stare and expression, and influence skeletomotor and autonomic activity. Interictally, patients with anterior cingulate cortex epilepsy often display psychopathic or sociopathic behaviours. In other clinical examples of elevated anterior cingulate cortex activity it may contribute to ties, obsessive-compulsive behaviours, and aberrent social behaviour. Conversely, reduced cingulate activity following infarcts or surgery can contribute to behavioural disorders including akinetic mutism, diminished self-awareness and depression, motor neglect and impaired motor initiation, reduced responses to pain, and aberrent social behaviour. The role of anterior cingulate cortex in pain responsiveness is suggested by cingulumotomy results and functional imaging studies during noxious somatic stimulation. The affect division of anterior cingulate cortex modulates autonomic activity and internal emotional responses, while the cognition division is engaged in response selection associated with skeletomotor activity and responses to noxious stimuli. Over-all, anterior cingulate cortex appears to play a crucial role in initiation, motivation, and goal-directed behaviours. The anterior cingulate cortex is part of a larger matrix of structures that are engaged in similar functions. These structures from the rostral limbic system and include the amygdala, periaqueductal grey, ventral striatum, orbitofrontal and anterior insular cortices. The system formed by these interconnected areas assesses the motivational content of internal and external stimuli and regulates context-dependent behaviours.
Although sleep paralysis had been treated as one of the symptoms of narcolepsy, recently it has become recognized as occurring frequently in normal individuals. However, among the few published studies that have examined sleep paralysis, there are great discrepancies in its reported prevalence. These discrepancies could be attributed to differences in survey methods, to the description of the symptom employed in each study, or to the race or culture of the research participants. We administered a questionnaire, with equivalent Japanese and English forms, to 86 Canadian and 149 Japanese university students. Although the reported prevalence of sleep paralysis was almost the same (Canada: 41.9%, Japan: 38.9%), the characterization of the phenomenon differed greatly between the two samples. Over 55% of the Canadian and only about 15% of the Japanese students regarded the experience as 'a kind of dream.' This difference may be one of the reasons for the varying prevalence noted in previous studies. Although many Japanese students (40.5%) and a very small number of Canadians (3.5%) usually prefer the supine position while sleeping, the majority of both groups (Canada: 57.9%, Japan: 83.8%) reported that, during the episodes of sleep paralysis, they found themselves in the supine position.
In Japan, a set of experiences called kanashibari is considered identical with isolated sleep paralysis. We investigated this phenomenon by means of a questionnaire administered to 635 college students (390 men and 245 women). Of all subjects, about 40% had experienced at least one episode of kanashibari [subjects of K(+)]. Therefore, isolated sleep paralysis is apparently a more common phenomenon than is usually appreciated. About half of the subjects of K(+) reported that they had been under "physical or psychological stress" or in a "disturbed sleep and wakefulness cycle" immediately before the episode. Many subjects of K(+) experienced the first episode in adolescence. In the distribution of age of first attack, the peak occurred at an earlier age in women subjects than in men subjects. These findings suggest that two factors influence the occurrence of the phenomenon. One is exogenous physical or psychological load and the other is endogenous biological development.
During an experiment on nocturnal sleep interruption, we observed a unique case of hallucination without sleep paralysis during the sleep-onset REM period in a normal individual. We documented the polysomnogram recorded during this hallucination. The polysomnogram showed a mixed pattern of Stages REM and W, with muscle-tone inhibition, rapid eye movements (REMs), slow eye movements (SEMs), and abundant alpha EEG trains. The blocking of alpha EEG trains by REMs appeared to reflect visual processing similar to that which occurs during waking. This hallucination was distinct from ordinary sleep-onset mentation in that it included strong emotional components and in that the subject simultaneously experienced both hallucinatory mentation and reality contact. This hallucination may resemble sleep paralysis with regard to its physiological and psychological background, and the discrimination of these two phenomena may depend on the subject's own awareness of muscle-tone inhibition.
Most normal subjects keep their arterial oxygen saturation above 90% both when awake and during sleep. However, some seemingly normal subjects intermittently desaturate during sleep and Block et al. [5] found this was much more common in men than women. Unfortunately, in that study four obese males contributed the majority of the desaturation and the majority of the irregular breathing. Furthermore, the men were older than the women in that study and there was also a tendency for the oxygen saturation when awake to be lower in the men than in the women. We therefore studied the breathing patterns during sleep of 40 normal subjects (21 women, 19 men), all of whom were within 12% of average body weight. None of these subjects described daytime somnolence or disturbed nocturnal sleep. This study showed [8] that there was no sex difference between normal men and normal women at any age in either the amount of nocturnal irregular breathing or in the lowest oxygen saturation achieved during sleep. The study did, however, confirm the observation [4, 7, 21] that irregular breathing and desaturation during sleep are commoner in older subjects.
The objective of this chapter is to explore the possible relationship between proneness to lucid dreaming and the occurrence of a phenomenon known as the out-of-the-body experience (henceforth, OBE). In an OBE, the experient (or OBEr) has the impression that consciousness or the center of awareness is outside the physical body. Among the general public, the OBE commonly is regarded as a mystical phenomenon within which context it is known as astral projection or astral travel. Particularly in recent years, however, OBEs have attracted scientific interest among psychologists, parapsychologists, and psychiatrists so that there is a growing quantity of data as to the nature of the experience.
Lucid dreams have much in common with out-of-body experiences, or OBEs. Harvey Irwin has described, elsewhere in this book, the empirical evidence for similarities and statistical relationships between the two experiences. I believe these relationships are important: so much so that any theory of one experience must also be able to account for the other.KeywordsBody ImageSensory InputMental ImageryTestable PredictionAltered StateThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
The studies reported in the following articles are aimed at providing a comprehensive, detailed, and quantitative picture of cognition in human dreaming. Our main premises are that waking, REM sleep, and non-REM (NREM) sleep represent physiologically distinct and identifiable brain states and that the differences between waking, REM, and NREM mentation reflect these physiological differences. We have studied dreams at a formal level of analysis and, in these papers, have studied the specific dream properties of emotions, bizarre transformations, scene shifts, and plot coherence, in adults and 4- to 10-year-old children, as part of a larger effort to map state-dependent mental phenomena back onto the varying neurobiological processes that must underlie them. We believe that such efforts will enhance our understanding not only of dreaming and its neurophysiological substrates, but also of the cognitive processes that dreaming shares with other unusual mental states.
Reviews the books, Using LISREL for structural equation modelling: A researcher’s guide and Principles and practice of structural equation modelling by E. Kevin Kelloway (see record 1998-08130-000) and Principles and practice of structural equation modelling by Rex B. Kline (see record 1998-02720-000). Structural equation modeling (SEM) is one of the most rapidly growing analytic techniques in use today. Proponents of the approach have virtually declared die advent of a statistical revolution, while skeptics worry about the widespread misuse of complex and often poorly understood analytic methods. The two new books under review are therefore timely. Both are valuable, but differ in important ways. Kevin Kelloway's book is directed at the researcher with little knowledge of structural equation modeling and is intricately linked to one of the more popular structural equation modeling programs, LISREL. For researchers keen to begin analyzing data quickly, this book is an invaluable resource that will speed one's introduction to SEM. On the other hand, the volume written by Rex Kline represents one of the most comprehensive of available introductions to the application, execution, and interpretation of this technique. The book is written for both students and researchers who do not have extensive quantitative background. It is especially attentive to quantitative issues common to most structural equation applications. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Special issue: Methodological developments in personality research. Examines the usefulness of factor analysis (FA) in developing and evaluating personality scales that measure limited domain constructs. The approach advocated follows from the assumptions that a scale ought to measure a single construct, that FA ought to be applied routinely to new personality scales, and that the factors of a scale are important if they are differentially related to other measures. A detailed study of the Self-Monitoring Scale illustrates how FA can help determine what a scale measures. A 2nd example uses the self-esteem literature to illustrate how FA can clarify the proliferation of scales within a single content domain. Confirmatory techniques are also introduced as a means for testing specific hypotheses.
philosophical contrasts between exploratory and confirmatory factor analysis / inductivism versus hypotheticism in science
fundamentals of confirmatory factor analysis / identification / methods of parameter estimation / evaluating a confirmatory factor analysis model
applications for confirmatory factor analysis / second-order factors (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Investigated the emotional profile of dreams and the relationship between dream emotion and cognition using a form that specifically asked Ss to identify emotions within their dreams. 200 dream reports were collected from 14 female and 6 male university students. Anxiety/fear was reported most frequently, followed by joy/elation, anger, sadness, shame/guilt, and, least frequently, affection/eroticism. Unexpectedly, there was no significant gender difference in the profiles of emotion reported. A significant correlation was found between the occurrence of bizarreness and major shifts in emotion. Results support the conclusion that dreaming is a mental state whose general emotional features are widely shared across individuals and are strongly linked to cognitive features within individual dreams. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Presents a medical interpretation of a culturally stereotyped affliction of sleep paralysis in Newfoundland (described by D. J. Hufford, 1976) known as "Old Hag." During "Old Hag" paralysis, the afflicted individual finds him/herself unable to move but is conscious and able to hear. The affliction usually follows a period of sleep and is sometimes accompanied by hallucinations. In Newfoundland, the affliction is attributed to attack by the spirit of a witch who sits on the sleeper. The condition is defined medically as sleep paralysis with hypnogogic hallucinations and is examined with regard to physiological, psychogenic, and social factors. Sleep deprivation, long work hours, passive/aggressive conflict, and hostility suppression are identified as factors that may contribute to the condition. Examples of sleep paralysis in other cultures are presented. (56 ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)
In a positron emission tomography (PET) study of hypnotic auditory hallucinations (Szechtman, Woody, Bowers and Nahmias, 1998), we found that activation of the right anterior cingulate seems to be critically implicated in the experience of a hallucination. Here we discuss two alternative interpretations of this result, consistent with the known functions of this region. First, hallucinations may occur when affect drives the generation of an internal percept, and then outwardly directed attention leads to the misattribution of this percept to the external world. This interpretation is consistent with the model of hallucinations by Bentall (1990). Alternatively, hallucinations may stem from what we herein term a ‘feeling of knowing’, or conviction that a stimulus is out there, around which the hallucinator constructs and rationalizes a percept. We relate the latter proposal to ideas by Rapoport (1989) and Damasio (1994) concerning the biological underpinnings of the sense of external reality. We also suggest ways that research on the neural bases of hypnosis might offer clues about the neural bases of psychopathologies, such as obsessive-compulsive disorder and schizophrenia. Copyright © 2000 British Society of Experimental and Clinical Hypnosis
This article is a nontechnical introduction to the use of structural equation models in personality research Although such models can be fruitfully used to address a variety of important theoretical issues, the substantive focus in this article is on the use of such models for elucidating the construct validity of personality measures We include numerous more specific topics under our treatment of construct validity First of all, we show how structural equation models can be applied to the issues of convergent and discriminant validity Do our variables measure the constructs we want them to measure and not other constructs that we would prefer not to measure? Second, we show the utility of structural equation models for predictive validity Do our variables reliably predict other constructs with which they are theoretically linked? Finally, we examine the stability of personality constructs through structural equation models Through-out, our emphasis is on the particular advantages that structural equation models bring to these analytic tasks Ultimately, such models must be used in the service of theory, and when used appropriately, they can help us to refine both our measures and our theories of individual differences
This paper presents a theory of the “I” and its relationship to consciousness and cognition, which integrates its relationship to the selves and the person. When cerebral neural systems are unable to automatically process information, they become disequilibrated. The person's “I” is the experiential display of autoregulatory orientational operations when the limbic brain/frontal lobe matrix becomes disequilibrated. The “I” and the sources of disequilibration are displayed in consciousness, facilitating cognition. Cognition and consciousness produce the experience of selves/person in relationship to plans and action programs (behavior) designed to stabilize disequilibrated neural structures.
In a sample of 1798 university undergraduates (females, n = 976; males, n = 822) 21% reported one or more episodes of sleep paralysis, and there was no significant sex difference in this regard. Most (98.4%) sleep paralysis sufferers reported at least one psychological symptom (e.g., hallucinations) accompanying their last (or only) episode. A total of 190 sleep paralysis reporters and 221 controls who did not report sleep paralysis were further tested on a battery of instruments that assessed other sleep phenomena (e.g., nightmares), psychopathology, reported physical and sexual abuse, and imaginativeness. A composite index of imaginativeness predicted both the occurrence and frequency of sleep paralysis and also the intensity of sleep paralysis symptomatology. A salience hypothesis of sleep paralysis occurrence was developed to account for these findings.
The nature and time course of sleep onset (hypnagogic) mentation was studied in the home environment using the Nightcap, a reliable, cost-effective, and relatively noninvasive sleep monitor. The Nightcap, linked to a personal computer, reliably identified sleep onset according to changes in perceived sleepiness and the appearance of hypnagogic dream features. Awakenings were performed by the computer after 15 s to 5 min of sleep as defined by eyelid quiescence. Awakenings from longer periods of sleep were associated with (1) an increase in reported sleepiness, (2) a decrease in the length of mentation reports, (3) a decrease in the frequency of reports of normal, wake-like thoughts, (4) an increase in the frequency of "unusual thoughts," and (5) increased frequencies of formal dream features, including visual hallucination, self-representation, fictive movement, narrative plot, and bizarreness. While sleep-onset reports can include all features of rapid eye movement (REM) dream reports, the number of such features is markedly reduced at sleep onset, suggesting that this mentation is a greatly diminished version of REM dreaming.
The neuroanatomical substrates controlling and regulating sleeping and waking, and thus consciousness, are located in the brain stem. Most crucial for bringing the brain into a state conducive for consciousness and information processing is the mesencephalic part of the brain stem. This part controls the state of waking, which is generally associated with a high degree of consciousness. Wakefulness is accompanied by a low-amplitude, high-frequency electroencephalogram, due to the fact that thalamocortical neurons fire in a state of tonic depolarization. Information can easily pass the low-level threshold of these neurons, leading to a high transfer ratio. The complexity of the electroencephalogram during conscious waking is high, as expressed in a high correlation dimension. Accordingly, the level of information processing is high. Spindles, and alpha waves in humans, mark the transition from wakefulness to sleep. These phenomena are related to drowsiness, associated with a reduction in consciousness. Drowsiness occurs when cells undergo moderate hyperpolarizations. Increased inhibitions result in a reduction of afferent information, with a lowered transfer ratio. Information processing subsides, which is also expressed in a diminished correlation dimension. Consciousness is further decreased at the onset of slow wave sleep. This sleep is controlled by the medullar reticular formation and is characterized by a high-voltage, low-frequency electroencephalogram. Slow wave sleep becomes manifest when neurons undergo a further hyperpolarization. Inhibitory activities are so strong that the transfer ratio further drops, as does the correlation dimension. Thus, sensory information is largely blocked and information processing is on a low level. Finally, rapid eye movement sleep is regulated by the pontine reticular formation and is associated with a "wake-like" electroencephalographic pattern. Just as during wakefulness, this is the expression of a depolarization of thalamocortical neurons. The transfer ratio of rapid eye movement sleep has not yet been determined, but seems to vary. Evidence exists that this type of sleep, associated with dreaming, with some kind of perception and consciousness, is involved in processing of "internal" information. In line with this, rapid eye movement sleep has higher correlation dimensions than slow-wave sleep and sometimes even higher than wakefulness. It is assumed that the "near-the-threshold" depolarized state of neurons in the thalamus and cerebral cortex is a necessary condition for perceptual processes and consciousness, such as occurs during waking and in an altered form during rapid eye movement sleep.
Recent PET imaging and brain lesion studies in humans are integrated with new basic research findings at the cellular level in animals to explain how the formal cognitive features of dreaming may be the combined product of a shift in neuromodulatory balance of the brain and a related redistribution of regional blood flow. The human PET data indicate a preferential activation in REM of the pontine brain stem and of limbic and paralimbic cortical structures involved in mediating emotion and a corresponding deactivation of dorsolateral prefrontal cortical structures involved in the executive and mnemonic aspects of cognition. The pontine brainstem mechanisms controlling the neuromodulatory balance of the brain in rats and cats include noradrenergic and serotonergic influences which enhance waking and impede REM via anticholinergic mechanisms and cholinergic mechanisms which are essential to REM sleep and only come into full play when the serotonergic and noradrenergic systems are inhibited. In REM, the brain thus becomes activated but processes its internally generated data in a manner quite different from that of waking.
Recent research in the neurobiology of dreaming sleep provides new evidence for possible structural and functional substrates of formal aspects of the dream process. The data suggest that dreaming sleep is physiologically determined and shaped by a brain stem neuronal mechanism that can be modeled physiologically and mathematically. Formal features of the generator processes with strong implications for dream theory include periodicity and automaticity of forebrain activation, suggesting a preprogrammed neural basis for dream mentation in sleep; intense and sporadic activation of brain stem sensorimotor circuits including reticular, oculomotor, and vestibular neurons, possibly determining spatiotemporal aspects of dream imagery; and shifts in transmitter ratios, possibly accounting for dream amnesia. The authors suggest that the automatically activated forebrain synthesizes the dream by comparing information generated in specific brain stem circuits with information stored in memory.
This paper describes a syndrome of psychological and physical symptoms involving body paralysis and hallucinations traditionally interpreted in Newfoundland as an attack of 'Old Hag'. Folk theories of cause and treatment are outlined based on 13 months of field research in a community on the northeast coast of Newfoundland. Data derived from the responses of 69 adults to the Cornell Medical Index (CMI) indicate that there are no significant differences in psychological or physical illness complaints between adults who have experienced the Old Hag and adults who have not had this experience. The striking similarity between the Old Hag experience and a clinical condition called sleep paralysis is analyzed, and the implications of viewing the Old Hag as sleep paralysis are discussed within the context of current theoretical issues in transcultural psychiatry.
Examines existing literature on the hypnagogic state , a term used in a descriptive sense to emphasize the fact that numerous phenomena characterize the drowsy interval between waking and sleeping. Major methodological issues are considered, psychological and physiological aspects of the hypnagogic state are reviewed, and theories concerned with the genesis and function of hypnagogic phenomena are critically evaluated. Possible directions for future research are outlined, with emphasis placed on elucidating the patterns of psychological and physiological phenomena which characterize the hypnagogic state. (131 ref)
1. In cats anesthetized with chloralose, responses of medial pontomedullary reticular neurons to stimulation of the body surface, vestibular nerves, superior colliculi, pericruciate cortices, cerebral peduncles, and spinal cord were studied at different stimulus rates. Raising the rate from 1/10 s to between 1/4 s and 2/s caused a significant decrement or increment in the response of most neurons tested. Response decrement typically began near the beginning of the higher frequency stimulus sequence and increased throughout the sequence. Response increment usually began somewhat later, rose to a peak, and then declined. Recovery from response decrement or increment usually occurred within 30-60 s at a 1/10 s stimulus rate.2. Measurements of response latency and of changes occurring in the initial and longer latency portions of responses indicated that all components of a response typically decreased or increased in parallel. Background spontaneous activity did not change during response decrements, but sometimes increased during response increment.3. Where changes could be detected, response decrement usually developed more rapidly when a sequence of repetitive stimulation was repeated.4. Response decrement was most pronounced at the highest stimulation rates and lowest stimulus intensities. Response increment was usually maximal at a stimulus rate of 1/s: at lower rates less increment occurred; at higher rates responses began to exhibit decrement.5. Response changes varied with the type of stimulus applied. Response decrements predominated when the body surface, vestibular nerves, or ipsilateral superior colliculus were stimulated. Approximately equal amounts of response increment and decrement were produced by repetitive stimulation of the cerebral peduncles and contralateral superior colliculus. Stimulation of the surface of the pericruciate cortex or of the spinal cord usually produced a long-lasting response increment.6. Generalization of response decrement and increment was observed in cases where trains of stimuli at a rate of 2/s applied to one point produced changes in the response to stimulation of another point which was tested once per 10 s and where single-shock stimulation of the first point was without effect on the test response. Generalization of response decrement occurred most often when two nearby points were stimulated. Generalization of response increment appeared to spread widely between distant cutaneous points and stimuli of different kinds.7. The response decrement and increment observed in medial pontomedullary reticular neurons displayed most of the parametric features of behavioral habituation and sensitization (8, 33) and therefore appear to represent neural analogs of these latter phenomena. The properties of response decrement suggest that it may occur to a large extent within afferent pathways leading to medial reticular neurons...
This study asks whether auditory hallucinations are reflected in a distinctive metabolic map of the brain.
Regional brain metabolism was measured by positron emission tomography with [18F]-fluorodeoxyglucose in 12 DSM-III schizophrenic patients who experienced auditory hallucinations during glucose uptake and 10 who did not. All patients were free of neuroleptics and 19 had never been treated with neuroleptics. Nine patients were reexamined after 1 year to assess effects of neuroleptic treatment.
Compared with the patients who did not experience hallucinations, the patients who did experience hallucinations had significantly lower relative metabolism in auditory and Wernicke's regions and a trend toward higher metabolism in the right hemisphere homologue of Broca's region. Hallucination scores correlated positively and significantly with relative metabolism in the striatum and anterior cingulate regions. Neuroleptic treatment resulted in a significant increase in striatal metabolism and a reduced frontal-parietal ratio, which was significantly correlated with a decrease in hallucination scores.
Auditory hallucinations involve language regions of the cortex in a pattern similar to that seen in normal subjects listening to their own voices but different in that left prefrontal regions are not activated. The striatum plays a critical role in auditory hallucinations.
Following a set of studies concerning the intrinsic electrophysiology of mammalian central neurons in relation to global brain function, we reach the following conclusions: (i) the main difference between wakefulness and paradoxical sleep lies in the weight given to sensory afferents in cognitive images; (ii) otherwise, wakefulness and paradoxical sleep are fundamentally equivalent brain states probably subserved by an intrinsic thalamo-cortical loop. From this assumption, we conclude that wakefulness is an intrinsic functional realm, modulated by sensory parameters. In support of this hypothesis, we review morphological studies of the thalamocortical system, which indicate that only a minor part of its connectivity is devoted to the transfer of direct sensory input. Rather, most of the connectivity is geared to the generation of internal functional modes, which may, in principle, operate in the presence or absence of sensory activation. These considerations lead us to challenge the traditional Jamesian view of brain function according to which consciousness is generated as an exclusive by-product of sensory input. Instead, we argue that consciousness is fundamentally a closed-loop property, in which the ability of cells to be intrinsically active plays a central role. We further discuss the importance of spatial and temporal mapping in the elaboration of cognitive and perceptual constructs.
Hallucinations are among the most severe and puzzling forms of psychopathology. Although usually regarded as first-rank symptoms of schizophrenia, they are found in a wide range of medical and psychiatric conditions. Moreover, a substantial minority of otherwise normal individuals report hallucinatory experiences. The purpose of this article is to review the considerable research into the cognitive mechanisms underlying (particularly psychotic) hallucinations that has been carried out and to integrate this research within a general framework. The available evidence suggests that hallucinations result from a failure of the metacognitive skills involved in discriminating between self-generated and external sources of information. It is likely that different aspects of these skills are implicated in different types of hallucinatory experiences. Further research should focus on specific metacognitive deficits associated with different types of hallucinations and on treatment strategies designed to train hallucinators to reattribute thoughts to themselves.
We report the cases of 10 patients with seizures and autoscopic phenomena, which include seeing one's double and out-of-body experiences, and review 33 additional cases of autoscopic seizures from the literature. Autoscopic phenomena may be symptoms of simple partial, complex partial, or generalized tonoclonic seizures. Autoscopic seizures may be more common than is recognized; we found a 6.3% incidence in the patients we interviewed. The temporal lobe was involved in 18 (86%) of the 21 patients in whom the seizure focus could be identified. There was no clear lateralization of lesions in patients with ictal autoscopy. The response of autoscopic episodes to treatment usually paralleled that of the underlying seizure disorder. Autoscopic phenomena are likely to be discovered only on specific questioning of patients with epilepsy and may be an important, distressing feature of a chronic seizure disorder.