The spiritist interpretation of dreams

"The dream" by Pierre-Cécile Puvis de Chavannes, 1883. Source: Wikipedia.

"Poor human beings! how little do you know of the commonest phenomena of your life! You

fancy yourselves to be very learned, and you are puzzled by the most ordinary things. To

questions that any child might ask, 'What do we do when we are asleep?' 'What are dreams?'

you are incapable of replying." (1)

“One day it will have to be officially admitted 

that what we have christened reality is 

an even greater illusion than the world of dreams.” ― Salvador Dali

We sleep a considerable portion of our lives, more precisely, about one-third of our incarnate lives. What happens in this state? It is easy to understand the need for sleep - so natural that we hardly question its importance - however, how do we justify dreams? What does the understanding of the dual nature of the human being, allowed by the Spiritist knowledge, help us to understand the mechanism of dreaming? 

The dream experience is quite different from the ordinary experiences of the waking state. The latter admits "witnesses", who share these experiences publicly. If I travel with my family to a tourist destination, the experiences I had there are the same my relatives had. In dreams, however, this does not apply. Thus, if I dream about going to a distant place with my relatives, they will not confirm the same experience if I question them about their dreams. In principle, the whole experience of dreaming is private, that is, lived only in the "first person", by myself exclusively. Such a striking difference makes dreams to be considered mental experiences par excellence, that is, experiences created solely by the dreamer's mind. 

Another distinguishing feature of dreams (I have already experienced this myself) is the apparent lack of causal connection among events within a dream. What happens at a particular moment - even though the apparent cause is declared in the dream - is not related causally to the following dream action. I remember a dream when I parked a car in a certain place. After other facts in the dream, when I return to get the car, it was no longer there or, at least, I could not remember where I had left the car in the dream... But I also remember dreams in which I was aware I was dreaming and could also keep the details of previous dreams connected to the last one I was having. In these cases, I was just finishing an adventure of a few nights before (someone told me in the dream): a situation best described as a "lucid dream".

The dream as a mnemonic synthesis of past experiences of the soul during sleep.

Dreams are the remembrance of what your spirit has seen during sleep, but you must remark that you do not always dream, because you do not always remember what you have seen, or all that you have seen. Your dreams do not always reflect the action of your soul in its full development; for they are often only the reflex of the confusion that accompanies your departure or your return, mingled with the vague remembrance of what you have done, or of what has occupied your thoughts, in your waking state. (1)

As already described in Question #402 in The Spirit's Book (1), dreams do not reduce themselves simply to the state of the soul freed from the body. If this were so, the experience, although private, should be consistent, in other words, dreams would be indistinguishable from "out-of-the-body" experiences. Dreams may be described rather as a kind of mnemonic synthesis of what occurs during sleep which is meaningful to the spirit; a re-construction or assembly, greatly affected by memories of past experiences, of what is important to the mind during sleep. Although the mechanism is fully unknown, this synthesis or composite is constructed from almost everything relevant to the individual at the moment of awakening: desires, fears, the reinterpreted experience of the previous day, memories of the present and past lives, and even past experiences the spirit has had recently, that is, the very memories of other dreams.

For me, the immense majority of people (including myself) cannot perfectly retain, through the "prism of the brain", the memories acquired by the senses of the soul during the dreaming state. The events of the dream are therefore recreated from a "bank of memories", almost entirely based on previous experiences of the waking state. It is like creating a new movie using a sequence of edited scenes from old films. In this "editing" process, the memory bank is accessed and its symbols, scenes or poses are used to "synthesize" a memory of the actual experience. Thus, after waking up, most recollected sequences are often erratic or does not fit into a rational or logic arrangement.

For example, imagine that I, in spirit state, was in contact with other people during sleep. When I awake, the remembrance process will most likely substitute the personality whom I have been in contact with by other people I recognize in the vigil state: sometimes a friend I know later was indeed awakened, or another person whom I have long forgotten and so on. It is even possible that the dream is filled out with an image of a discarnate relative. And so we usually wake up with the impression of having been in contact with that dead relative, but in fact, that was not true. It was rather a recreation because in no way my physical brain is able to sustain faithfully the images of my actual experience as a spirit in the dream. Only the script is more or less similar. The mnemonic assembly is necessary to give a meaning of those experiences lived in the dream to my consciousness in the awakened state. We should remember that the experiences of the dream do not reach the soul through the common pathways of the material senses (the nervous system). Therefore, they are reinterpreted when they finally reach the brain when we awake.

So, those were not the ones I have been in contact with when I dreamed about my deceased mother, father or any other relative? Not necessarily. A somewhat different situation occurs in the already mentioned lucid dreams, which are a category of rare and peculiar dreams. In them, the dreamer knows he/she is dreaming or is having the experience. In the dreams I had with my deceased mother, I had a distinct impression that she came to visit me. Amazingly, the dream environment was the bed I was lying - somehow I know it - and the dream finished when I woke up in tears. These particular dreams differ greatly from the immense majority of banal, meaningless dreams we have often because they are full of meaning to us.

The idea of dreams as a process of re-creation of experience of the soul during sleep by assembling preexisting memories allows us to explain the so-called "premonitory dreams". In fact, these can also be recreated from previous images, but they deal with future events based on the experience of the soul in the Beyond regarding these facts. Trying to interpret them may be a frustrating practice because they only make sense to the dreamer who preserves their real meaning unconsciously. Moreover, premonition dreamers might not be competent in conveying or communicating the true meaning in time, which is a source of countless confusions.

In summary, we can divide the impressions caused by the dreams in three levels of meanings:

1. The deep meaning, ultimately existing only for the soul, that is, as an unconscious "memory" impressed to the incarnate being, an "unfelt awareness". The sense can be recapitulated in other dreams or invoked in lucid dreams. It certainly survives physical death as the heritage of the soul experience,
2. The fragmented vigil meaning, recreated on the base of preexisting images or memories of the vigil state, the materialized meaning for the waking being, perhaps to be forgotten with physical death,
3. The sense conveyed to others, depending on our ability to communicate the dream experience to others in the incarnate world. This meaning can cause a very different impression, making their "interpretation" difficult, although in some anomalous case, the meaning is very clear. 

"Joseph interpreting Pharaoh’s dream" (Genesis cap 41, 14-36),
The Phillip Medhurst Picture Torah 199. Source: Wikipedia.

The importance of anomalous dreams

Presently, most of the theoretical impasse regarding the most popular conceptions of the mind is due to their exclusive reference to the events taking place with the immense majority of people. I understand the reason from a practical point of view. Statistically, it makes sense to devote research effort to what happens most of the time. By doing this, however, we sacrifice the understanding of the deeper causes in detriment of what is more frequent. Thus the anomalies that occur with only a few are swept under the rug by explanations seemingly applicable to what is general. It is reasonable to ask if the truest theory is the one fitting the majority of the facts or the one leaving no fact aside. In medicine, one does not learn anything about diseases by studying only healthy people. Therefore, anomalies should be regarded since they are a way to establish correlations and to explain the exceptions beyond the rule.

The so-called "anomalous dreams" represent precisely this situation. Unlike ordinary dreams, they resemble lucid dreams by bringing meaningful messages containing "anomalous content". An elucidating work about anomalous dreams is due to S. Krippner and L. Faith entitled "Exotic dreams: A cross-cultural study" (2). In this work, the authors identified (from a set of about 1700 dream reports), nearly 185 (or 8%) considered "exotic". Such reports were then classified according to several types: healing dreams, lucid dreams, creative dreams, dreams with out-of-body experiences, shared dreams, dreams within dreams (as I had), dreams of past lives, visitation dreams, etc.

The so-called "shared dreams" are particularly interesting. These are reports of people who experience mutual dreams or dreams whose content is partially shared among individuals. Thus, the "first person" character of dreams may be weakened (3).

In creative dreams, Krippner and Faith reported dream narratives in which people were aided in dreams to solve problems of everyday life.

In a visitation dream, a painter from Japan reported having been advised by her father, who died in World War II, to choose her paintings and even on how to use the brush. The experience was highly significative and helped to improve the painter professional performance.

According to the authors in (2), dreams about tragedies (precognitive dreams) do not always end in a fatal way. They usually manifest themselves as the announcement of diseases or vulnerable situations of people at a distance.

Finally, the authors in (2) suggest a correlation between the incidence of anomalous dreams and the cultural environment in which they occur. In fact, this correlation is expected, considering that dreams are interpreted in terms of previous mental baggage. Therefore, the greater the individual' awareness about spiritual realities, the clearer will be their representation in exotic or peculiar dreams.

As for lucid dreams, it is possible that most people have already experienced - at least once in life - this kind of dream which would be more expected in cultures which value spirituality.

Conclusions

In this note, I have listed some relevant aspects to our understanding of the genesis and unfolding of dreams. A suitable explanation of the mechanism of dreams must both explain the dynamics with the vast majority of people, and the peculiar cases occurring with specific groups as well. Such anomalous experiences may also manifest at least once in people's life.

It is not possible to understand dreams without appealing to the dual nature of the human being, a simple reality that is able to explain both the reported exceptions and everyday life dreams. What we call dreams are, in fact, memories of events taking place during sleep, memories that are reconstructed out of other perceptions of facts lived by the person in the awaken state. This explanation agrees with the idea that, in the dream state, the spirit cannot excite the body directly (that is, the brain), because it is partially detached from it. In the process of "reassembling" the experience as a meaningful narrative to the vigil state, experiences of the present life (everyday facts, known people etc) are used, just as "extraordinary" memories (e. g., of previous lives, or other dreams etc).

The random, erratic or senseless impression of most dreams is a consequence of such reassembly of memories from a bank of internal fragments. In general, the meaning of dreams only exists unconsciously for the person who experiences it. It is very difficult to interpret dreams correctly, although this might be possible exceptionally.

The understanding that dreams are memories of the spiritual life allows us to explain a great variety of accounts considered "anomalous", which are then important sources confirming the proposed mechanism behind dreams. Without proper attention to such anomalous accounts, dreams are often considered merely as "hallucinations" or "fantasies" of the brain, showing no correlation with the true and hidden reality.

In addition to dividing dreams between "ordinary" and "peculiar" types, for most people, dreams may be further subdivided into "ordinary/common" and "lucid" dreams. In the last case, the dreamer knows he/she is dreaming and, therefore, can "control" the dream in principle. Apparently, such control is subjected to training (4).

It seems evident that dreaming is an important stage in the progress of the incarnate soul. By countless repetitions, the spirit liberates itself from the physical world and recalls its disembodied life. In a certain sense, dreaming is a training process for the ultimate physical deliverance that we call death.

References

(1) Question 402, "The Spirit's Book" (A. Kardec). Translated from French by Anne Blackwell. Online version here: http://geeaknorge.com/wp-content/uploads/2014/05/Spiritsbook.pdf (March 2019).

(2) Krippner, S., & Faith, L. (2001). "Exotic dreams: A cross-cultural study". Dreaming, 11(2), 73-82.

(3) Another work related to shared dreams is Davis, W. J., & Frank, M. (1994). "Dream sharing: A case study". The Journal of Psychology, 128 (2), 133-147.

(4) See, e. g., May E. C & LaBerge S. (1991) "Anomalous Cognition in Lucid Dreams". Science Applications International Corporation. In March 2019, this work can be downloaded here:

https://www.cia.gov/library/readingroom/document/cia-rdp96-00789r003100140001-2

Draft of a spiritist explanation of sleep paralysis

Our studies show that the invisible world surrounding us constantly acts on the visible world as one of the forces of Nature. Would the knowledge of these hidden forces that dominate and subjugate us constitute the key to many problems, the explanation of a lot of unnoticed things? If these effects can be afflictive, would the knowledge of the causes for such evil represent a mean to preserve us against it, just as the knowledge of electricity provided us the means of mitigating the perils of lightning? If we fail, we should complain only of ourselves because ignorance will not serve as an excuse. (A. Kardec, La Revue Spirite, July 1859, "Closing speech of the social year 1858-1859")

I looked for rest in the setting of a pleasant weekend afternoon. Sleep comes, but not in the usual way. Just before waking up, I begin to perceive everything around me. Through eyes half closed, I see the familiar decoration of my bedroom. Suddenly, panic and despair take hold of me: I cannot get up! I hear voices of relatives nearby who know I am asleep. I try to turn my head, but it turned into lead. I try to raise my arm over my abdomen, but it is now made of steel. How long do I stay in this state? I do not know, but, when I finally wake up, I have the strange feeling of having being separated from my body for an unknown period of time. What happened to me? I just went through an experience of sleep paralysis.

How many times did I have this experience? Probably, three times in my life. The so-called "sleep paralysis" is a rare occurrence in the life of an individual, however, statistically, it is much disseminated in the population. Also, my private experience is far from being the most common. In addition to the feeling of lack of "body control", people often describe hidden presences, anomalous perceptions of intrusive figures in the scene, adding terror to the unpleasant feeling of an immovable body. However, reports have a point in common: during sleep paralysis, the personality remains intact, aware of the reality around it, but, for some reason, cannot "adjust itself" to the body and ends up perceiving what appears to be a mixture of "reality" and "hallucination".

Hallucinations or reports of anomalous perceptions?

The term "hallucination" is relatively recent. Popularized by J. Étienne Esquirol around 1817, its modern meaning involves "a percept, experienced by a waking individual, in the absence of an appropriate stimulus from the extracorporeal world" (Blom 2009). Its widespread use substituted the previous term "Phantasia". In the works of A. Kardec, both "hallucination" and "apparition" refer to distinct phenomena. The distinction is of fundamental importance since skeptics of the spiritual nature of man obviously deny the existence of apparitions which exist as perceptions of a hidden world. In other words, to deny the existence of apparitions is to constrain the entire external world to the limits of ordinary human senses, which was disproven by modern science (physics in particular) for a wide class of material phenomena. The realm of psychic reality still awaits exploration.

Thus, many perceptions during sleep paralysis are repeatedly described as "hypnagogic" and "hypnopompic" hallucinations. These words were created by the Spiritualist philologist Frederic Myers (1843-1901), but they do not explain anything. These are seemingly scaring words for perceptions occurring before and after sleep, respectively, but no explanatory power.

Already in the XIXth century, reports of sleep paralysis called the attention of W. James as described by Hufford (2005):

It was about September of 1884... Suddenly I felt something come into the room and stay close to my bed. It remained only a minute or two. I did not recognize it by any ordinary sense, and yet there was a horrible ‘sensation’ connected with it. It stirred something more at the roots of my being than any ordinary perception. The feeling had something of the quality of a very large tearing vital pain spreading chiefly over the chest, but within the organism – and yet the feeling was not pain so much as abhorrence. At all events, something was present with me, and I knew its presence far more surely than I had ever known the presence of any fleshly living creature. I was conscious of its departure as of its coming; an almost instantaneously swift going through the door, and the ‘horrible sensation’ disappeared.

as the typical manifestation of the 'bedroom intruder' in the experience. The reader can find other reports on the internet taking into account Note 1.

In an interesting relationship of sleep paralysis and psychic phenomena, Proud (2009) describes Hufford (1989) report of a case in 1975, the so-called "Ghost of Bowling Green" in which some people experienced sleep paralysis in a haunted house. An important key to understanding sleep paralysis and definitely establishing their 'spirit' origin is the similarity of accounts across many cultures. As pointed out by Proud (2009):

Why, Hufford asks, are the “hallucinations” of SP sufferers, though separated in time and by culture, so remarkably similar? How does one explain such common sensations as being strangled, of having one’s bed shaken back and forth, or of being grasped by the hand? The same can be said of the voices SP sufferers hear, which, in Cheyne’s words, “are typically simple and direct.” Why don’t the messages of these voices vary all that much from SP sufferer to SP sufferer? And why – as shown in previous chapters – do people in haunted houses experience the same types of phenomena as SP sufferers?

Thus, the regularity of the experiences points to an external cause, albeit somehow altered by the semi-awake state. A crucial line of investigation to rule out the "hallucination" hypothesis is to investigate a possible connection between sleep paralysis and psychic phenomena. Another interesting conclusion by Proud is the link between sleep paralysis and claimed "UFO abductions". These later ones might be explained in terms of sleep paralysis episodes.

In summary,  some of the features of sleep paralysis are:

• The feeling of being "awake". The sensation of sleep paralysis is not of a dream. As pointed out by Parker and Blackmore (2002): "These results show that SP is significantly different from dreams, but is a remarkably uniform state, regardless of 'the dreamer's' gender".
• The environment is perceived realistically which adds to the feeling of being, in fact, awake during sleep paralysis;
• Inability to move which makes the subject a passive observer of his state;
• They are more often during awakening (only about 10% occur when one falls asleep, therefore, they often share a "hypnopompic" character);
• Occurrences seem to mainly affect young adults;
• The person who suffers paralysis is not under drug effects;
• Also, the paralyzed person is mentally healthy with no sign of mental illness of any sort (however, some accounts seem to correlate sleep paralysis with mental disorders, see Cheyene 2001)
• Some experiences describe breathing difficulties;
• The episodes are uncontrollable. They cannot be predicted and no infallible method of stopping them could be found yet;
• A strong feeling of lack of body control, hence the name "paralysis". During sleep paralysis consciousness remains active - it is not a dream state - although the person may feel displaced or not attached to the body. In my own experience I feel as if a "rubber band" connected my head to my other body's head;
• Some reports (about 1/4 of the cases) almost always describe the presence of a malignant entity or "thing" that observes the paralyzed person;
• A few reports describe complete out-of-body experiences.
• As described by Hufford (1989), careful investigations would reveal a hidden link between sleep paralysis and many psychic phenomena. 

Toward a Spiritist explanation

There is no definitive theory allowing us to integrate all conscious (and worse still unconscious) perception states in the brain. This is so in spite of the countless materialistic proposals in the literature. All materialistic "explanations" however presuppose from the start that sleep paralysis is just a variety of hallucinatory experience (remember, we start this discussion with a very brief reference to Esquirol and the word he invented), even though there is a common pattern behind all accounts. As such they supposed to be false perceptions created by the brain in spite of the similarities of reports. This is the most important and unproven assumption of these approaches. Now, it is obvious that false perceptions do exist - although they may be motivated by external stimuli that reach the nervous system – when the body is in an altered state of consciousness (as caused, for example, by drugs), the mind may hallucinate and create false impressions. However, from this, it does not follow logically that all impressions gained while awake are indeed false. Nor it is clear where and how these perceptions are created, that is, what is the real source of them. 

The inexistence of such complete theory of mind implies that hallucinations, in general, cannot be explained away easily, but only associated or correlated to certain mental states. Indeed none of our perceptions can be satisfactorily explained by modern neurologic theories. The use of complicated names does not help to explain anything either, nor any reference to precise subparts of the cerebral tissue where the onset of these states is allegedly located. As put forward by David Chalmers the roots of this state of affairs are the called “hard problem of mind”, so that we are still very far away from any solid explanation in spite of all progress made in neurobiology. This opens a universe of possibilities, including Spiritualist explanations. The existence of certain correlations between the use of drugs and unconformities in the nervous systems (mental disorders) does not authorize us to explain sleep paralysis in the same way. In many of the sleep paralysis reports, the person was not under the effect of drugs. Although sleep paralysis may affect from 3% to 6% of the population. it is still a rare event in the life of an individual. Most importantly, the events are uncontrollable. Thus there is no known way to induce sleep paralysis, it cannot be regarded as a mental disease affecting the population.

Indeed, the presence of a "malignant entity" is so frequent that many clinicians are forced to provide an explanation. Let us have a look at a good one:

It is argued that the sensed presence during sleep paralysis arises because of REM-related endogenous activation of a hypervigilant and biased attentive state, the normal function of which is to resolve ambiguities inherent in biologically relevant threat cues. Given the lack of disambiguating environmental cues, however, the feeling of presence persists as a protracted experience that is both numinous and ominous. (Cheyne 2001).

From our point of view, however, this is a typical ad-hoc construction, a mixture of linguistic elements common to certain mind approaches giving the impression of explanation based on the idea of false perceptions. Moreover, this idea only fits some reports and lacks generality which is the real challenge of theories of mental events.  It surely does not explain my own experience, I did not catch glimpse of any "mysterious threat". In fact, many sleep paralysis accounts are devoid of such presences. 

For Spiritism, the brain does not create the mental state, nor consciousness. It is indeed an interface for the mind manifestation. As a consequence, even if some physiological causes may be found associated with sleep paralysis, its dynamics cannot despise the true nature of the human being. All hallucinations, appearing as tangible objects to the mind (that give rise to the so-called "lucid dreams") have an origin in the spiritual element, be it the incarnate being a product of its mental activity or the disembodied spirit. In fact, some medium's accounts (as A. Luiz in F. Xavier literature) describe spirits having hallucinations, which suggests that the phenomenon is not destroyed by physical death since its origin is not in the physical brain.

"Achilles searching for the soul of Patroclus" by Johann Heinrich Füssli (1741-1825)

From the spiritist perspective, two main principles orient the understanding of sleep paralysis:

1. The dual nature of the human being: the biological evolution in humans are constantly providing experiences that begin to prepare the being for an unfolded life - between the two planes of existence (dreams are just part of these experiences). Sleep paralysis may be seen as normal "training" episodes in the material life of the incarnated spirit;
2. Spirits are everywhere" (6b). Probably many reports of strange presences - most often linked to feelings of evil - are actually brought about by disembodied entities;

Sleep paralysis, therefore, could be described as an "incomplete splitting" phenomenon, a threshold zone between the onset of sleep and the awakened state, when faculties typical of the disembodied spirit operate together but out of sync with the sensory faculties of the incarnate. During this condition, the person begins to feel the presence of other spirits (which are most often around us) but interpret them in an exaggerated way. Clearly, only a few people can delve into the spirit realm even during such altered state, so that the majority only experience the paralysis as a manifestation of this lack of synchronicity between the spirit and the material bodies. 

We speak about the human senses in terms of only five traditional perceptions: sight (vision), hearing (audition), taste (gustation), smell (olfaction), and touch. However, the feeling of belonging and controlling our (material) body is also a state of perception which, during sleep paralysis, is challenged. For the majority of people (including me), the first spirit perception corresponds to the feeling of another body which must be reattached to the material counterpart. Other people, however, start to see and hear the spirit realm around and mix these perceptions with the immediate material "reality" (the vision of the room, nearby recognizable voices etc).  

Many of those who go through sleep paralysis consider themselves agnostic or religiously neutral. However, during the episodes they found themselves asking for the protection of God in some way. Maybe this is an indication that during sleep paralysis the person is under a strict control of his unconscious mind - which is a manifestation of the true spirit consciousness. During sleep paralysis, they think much more as a free (but bound) spirit than as an incarnate.

Obsession or spirit possession

We do not believe that sleep paralysis involves obsessions or even the onset of an obsessive process - that is the person is under the evil influence of earthbound spirits. Obsessions hardly restrict their performance to sleep, the waking period of people under the obsessive influence is also altered. Therefore, there is no point in applying "spirit release" therapies to the occasional sufferer of sleep paralysis.

How to mitigate the negative feeling during sleep paralysis

The spiritist explanation has an advantage: it allows us to propose procedures that can, in theory (and there are confirming reports), reduce the stress of paralysis. 

Bearing in mind that sleep paralysis is a phenomenon of spirit-body splitting, we must regard full mental control and the adoption of a positive attitude with requests of superior protection - which often involves the act of praying - as practical steps towards mitigating the negative effects of sleep paralysis. However, we cannot ensure complete elimination of the episodes because other causes may be involved. 

As the person during sleep paralysis is fully "aware", she/he should, in fact, ask for superior protection (in accordance with the person's own religious orientation). Prayer is, in fact, a kind of mental signal launched in space by way of which the devotee asks for help.  Prayer allows one to get rid of the oppressive influence, reduce or even eliminate the action of annoying spirits during sleep paralysis. It strengthens (predisposes positively) the spirit under the stressing situation because it calls out the help of spirit protectors who knows how to cease the phenomenon. Prayer will always work when it has a serious aim and does not involve any abrogation of God's laws - which are conditions fulfilled by the troubled person during paralysis. 

In any way, we will only have an effective sleep paralysis therapy when all causes (both physical and spiritual) are fully acknowledged. Clearly, the spiritist contribution cannot be overlooked.

References

Adler, S. R. (2011). Sleep paralysis: Night-mares, Nocebos, and the mind-body connection. Rutgers University Press.

Chalmers, D. (2007). The hard problem of consciousness. The Blackwell companion to consciousness, 225-235.

Blom, J. D. (2009). A dictionary of hallucinations. Springer Science & Business Media.

Cheyne, J. A. (2001). The ominous numinous. Sensed presence and "other" hallucinations. Journal of Consciousness Studies, 8(5-6), 133-150.

Cheyne, J. A. (2003). Sleep paralysis and the structure of waking-nightmare hallucinations. Dreaming, 13(3), 163.

Hufford, D. (1989). The terror that comes in the night: An experience-centered study of supernatural assault traditions (Vol. 7). University of Pennsylvania Press.

Hufford, D. J. (2005). Sleep paralysis as spiritual experience. Transcultural Psychiatry, 42(1), 11-45.

Parker, J. D., & Blackmore, S. J. (2002). Comparing the content of sleep paralysis and dream reports. Dreaming, 12(1), 45.

Proud, L. (2009). Dark intrusions: An investigation into the paranormal nature of sleep paralysis experiences. Anomalist Books.

McCarty, D. E., & Chesson Jr, A. L. (2009). A case of sleep paralysis with hypnopompic hallucinations. Journal of clinical sleep medicine: JCSM: official publication of the American Academy of Sleep Medicine, 5(1), 83.

Notes

(1) Many sites in 2018 describe experiences with adjectives such as 'terrifying', 'chilling', 'truly terrifying' etc and I don't reproduce them here since it is impossible to know if they were invented. I was not scared in my experience, however, I know about the scary ones based on witnesses accounts cited by serious researchers. 

Medical Sites on sleep paralysis

• Sleep paralysis Project. A site with a "scientific" proposal for treating sleep paralysis which presupposes the manifestations are caused by a pathology in the brain. 
• Periodic Paralysis Association. Another medical site on sleep paralysis with a lot of information.