Why incubus attack

These 13 records reported on 14 k independent prevalence estimates. Figure 2 is a flow diagram showing the identification, screening, and inclusion of eligible publications. Table 1 lists the included studies by year of publication and alphabetically within a single year.

Full references are provided in the reference list. Figure 2. Flowchart for identification, screening, and inclusion of eligible publications.

Table 1. Quality assessment of the included studies on the prevalence of the incubus phenomenon. All studies reported lifetime prevalence rates of the incubus phenomenon. For additional information on the included samples, see Tables 1 and 2. Tables 3 and 4 show the items that compose the Newcastle-Ottawa Scale, as well as the item and total methodological scores per included study. Figure 3.

Forest plot for the random-effects model estimating the pooled prevalence of the incubus phenomenon. Note that prevalence estimates are also shown as a function of whether the estimate was derived from a random or a selected sample e.

In the selected samples, the pooled prevalence rate of the incubus phenomenon was about four times higher 0.

Even when accounting for variance due to selected and unselected samples, significant between-study heterogeneity remained. However, this could not be explained by the variables that were a priori defined as potential effect modifiers, i. Given that sleep paralysis is reported to have a higher prevalence in student samples relative to non-student samples derived from the general population 11 , we also tested for differences in prevalence rates of the incubus phenomenon between these specific groups.

The prevalence rates of the incubus phenomenon were somewhat higher in student samples 0. A test of publication bias was considered irrelevant, since our main outcome was a straightforward prevalence rate. That said, as noted earlier, we suspect that some of the original studies included in our analysis suffered from selection bias due to self-selection of eligible patients.

A systematic review and meta-analysis of published studies was performed to provide for the first time an estimate of the prevalence rate of the incubus phenomenon.

In the general population, its lifetime prevalence was found to be 0. The incubus phenomenon has been known since Antiquity 32 and belongs to a select number of neuropsychiatric syndromes that have shown a remarkably stable clinical presentation over time Moreover, it appears to be a universal phenomenon, in the sense that as far as we know it does not miss out any historical or contemporary population group. As a consequence, each and every culture has had to come to terms with it.

As these varying explanatory models appear to be grafted on a rather stereotypic set of clinical phenomena, Cheyne et al. This brief cultural-historical excursion demonstrates that, in an experiential sense, the incubus phenomenon has always been considered something extraordinary, even though in an epidemiological sense it is relatively common and ordinary as shown here. With a risk of 0.

However, this is not the case. Instead, the incubus phenomenon is the staple of a fringe group of writers and filmmakers, mostly in the horror genre For the rest, apart from Japanese pop culture with its numerous references to kanashibari 40 , and a rural population in Canada where the inhabitants are so well-acquainted with the incubus phenomenon that they perform practical jokes to make one another believe that they are having an attack 10 , we are still dealing here with a topic that in most societies is hardly known to the greater public and not much better known to many health professionals It may also be due to the fact that most instances of the incubus phenomenon are non-recurring 45 and that they rarely constitute prodromal symptoms of worse things to come.

That said, recurring attacks may occur. For sleep paralysis, an increased risk is primarily associated with narcolepsy and other sleep disorders 9 , 46 , alcohol intoxication 47 , posttraumatic stress disorder 38 , anxiety disorders 48 , exploding head syndrome 49 , sexual abuse 36 , stress 46 , and physical illness Other factors that may increase the risk for an attack include a supine sleeping position especially when complicated by apnea due to airway obstruction 50 , an irregular sleeping pattern 51 , and amphetamine use The consequences of our findings for future research and clinical practice are fourfold.

In the first place, a better dissemination of knowledge regarding the biomedical conceptualization of the incubus phenomenon in the general population might help to prevent or at least diminish catastrophic interpretations and, thus, help diminish the number of cases that go on to develop comorbid pathology.

Third, future editions of the major diagnostic classifications, such as the ICD and DSM systems, could include a specific diagnostic category describing the incubus phenomenon, to allow for proper diagnosis and an improved awareness of the condition.

Fourth, much work is required to gain better insight into the neurophysiology and neuropsychology of the incubus phenomenon and its possible although at present unlikely association with sudden death 7 , and to develop evidence-based treatment protocols for recurrent, isolated cases. The present study has several limitations. Like all meta-analyses, the quality of the outcome of our study stands and falls with the quality of the included studies. Although we followed strict procedures in conformity with the guidelines for systematic reviews and meta-analyses, we had to depend on the works of the original authors.

As the prevalence figures reported in some of those studies were substantially higher than others, we cannot exclude the possibility that some of them may have been biased by self-selection of eligible patients.

However, we were able to present prevalence rates for selected and random samples separately. We should note here that the random samples we report on were not composed of healthy individuals alone. Hence, the prevalence of the incubus phenomenon might be lower in groups of healthy individuals. Finally, due to the strictness of our procedure, the total number of studies to be analyzed was relatively small, at least in comparison with the number of studies on the related topic of sleep paralysis.

On the basis of this systematic review and meta-analysis of studies reporting on the prevalence of the incubus phenomenon, its lifetime prevalence rate in the general population was found to be 0. MM contributed to the conception and design of the work and to the acquisition and analysis and interpretation of data for the work, drafted and revised the work, gave final approval for the final version to be published, and agreed to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

HM and OB contributed to the interpretation of data for the work, revised the work, gave final approval for the final version to be published, and agreed to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

ZA and J-PB contributed to the acquisition, analysis, and interpretation of data for the work, revised the work, gave final approval for the final version to be published, and agreed to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

JDB contributed to the conception and design of the work and to the analysis and interpretation of data for the work, drafted and revised the work, gave final approval for the final version to be published, and agreed to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

The research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Hurd R. Sleep Paralysis. Google Scholar.

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Prevalence and correlates of sleep paralysis in adults reporting childhood sexual abuse. Jan Dirk Blom,a professor of clinical psychopathology at the University of Leiden in the Netherlands. The condition happens when a person is falling asleep or waking up. During sleep paralysis, two aspects of REM sleep, or rapid eye movement sleep, occur when a person is conscious.

During REM sleep , which is the period when a person typically dreams, the body's muscles are relaxed to the level of paralysis, presumably to prevent the sleeper from acting out his or her dreams, Blom said.

But when sleep paralysis takes place, the person's mind wakes up — however, the person is still dreaming, and the body is still paralyzed. What the afflicted person sees is a combination of their actual surroundings and a nightmare, which is projected onto the real world. The experience feels exceptionally real, Blom said. In the meta-analysis, which was published in November in the journal Frontiers in Psychiatry , the researchers looked at 13 studies of the incubus phenomenon that included nearly 1, people.

The researchers found that over 1 in 10 people, or 11 percent of the general population, will experience the incubus phenomenon in their lifetimes, Blom said. But in certain groups, the odds of "encountering" an incubus are higher. Among people with psychiatric disorders, as well as among refugees and — somewhat surprisingly — students, the odds of experiencing the incubus phenomenon are as high as 41 percent, Blom said.

The analysis also found that people sleeping on their backs are more likely to experience the phenomenon. Alcohol consumption and irregular sleeping patterns also make an incubus visit more probable, Blom said.