Comments:

Many patients come to see their doctors with subjective symptoms that are hard to evaluate, particularly in the setting of general practice or primary care.

As a start, one should try to rule out the use of any medication such as beta-blockers (especially propranolol) for high blood pressure, hyperthyroidism or anxiety, etc., which might cause a range of sleep disturbances. Abuse of substances such as cerebral stimulants should also be excluded.

One might consider a wide differential diagnosis, including sleep paralysis (either non-pathological, or as a manifestation of narcolepsy), schizophreniform breakdown with bizarre sensations and paranoid ideation, hysterical display in order to solicit attention, and, last but not least, a practical joke with the intention to scare others. If one could elicit a history of symptoms other than sleep paralysis, it might be tempting to entertain a provisional diagnosis of narcolepsy syndrome. A sleep polygram to scan the REM phase will often help. It is known that it is common to suffer an attack of sleep paralysis after a period of mental excitation or physical weariness in the daytime, on an unfamiliar bed (for example in a hotel), or after bereavement.

What may worry a clinician is the patient's seemingly steadfast belief in a demonic force at work. After all, thoughts involving the intrusion of alien influences, in particular those related to malevolent spirits, are frequently a feature of mental illness. It is therefore prudent to ascertain if her attribution has in fact a psychotic aetiology, which may be confirmed by the presence of other cardinal psychotic or Schneider's first rank symptoms.

There is a real, indeed clinically significant, difference between being inclined to believe and insisting on a belief that it was a demon or poltergeist that brought the affliction upon her. The latter is more akin to a delusion, whereas in the former case it is merely an instinctive explanation for an unpleasant and frightening experience. Put simply, it matters if the person concerned is fixed in the belief that the incident of sleep paralysis arose from an exogenous malevolent cause, or if she only thinks that a malicious force might be at work. In other words, the uninvited harassment by the visitant was, in Kleinman's words,¹ an explanatory model of her malaise. It is common for a patient to present her problem in the form of a narrative; that is, one usually makes an account of what has happened by way of a story. The degree of conviction needs to be put to the acid test.

Delusions are said to be associated with more than 75 clinical conditions.² Given such an enormous variety and distinctiveness of ideas found across cultures, the criteria by which beliefs are perceived as abnormal are not always easy to delineate. Normally any beliefs that are not shared by other members of the community can be seen as unusual.

In order to be called a delusion, an idea must be shown to be clearly outside the range of normal beliefs for the culture to which the patient belongs. An appreciation of congruence with the patient's own culture is essential in reaching an accurate diagnosis. To this end, a clinician must understand the culture in which individuals are embedded before deciding whether the beliefs they hold are really abnormal and if they are pathognomonic of an underlying psychiatric disorder. On the one hand, if the content of these beliefs is derived from the patient's cultural milieu, it should be recognised as such by other members of the culture. On the other hand, if a belief is abnormal and culturally unfamiliar to members of the same community and is accompanied by functional impairment or culturally inappropriate behaviour, then it is likely to be a sign of illness.³

The patient's own projected, perhaps idiosyncratic, interpretation of the bizarre experience is worth some exploration. It is possible that her fear and thence her presumption of "visitation" by a spirit might follow an unhappy incident such as having accidentally kicked on the tablet of an Earth god (土地公tudi gong) or stepped on the paper offerings for a deceased, or guilt arising from inadvertently offending some spirits. It is worthy of note that her chief complaint of being pressed upon by a spirit on her bed has a substantial colouring of cultural heritage. To the extent that this is sanctioned by cultural tradition, the complaint is culture-bound, or more accurately, culture-specific.⁴

As Helman⁵ explained, possession can be a normative experience, and people are only possessed when they consider they are and when other members of their society endorse this claim. Indeed, it is a culturally specific way of presenting and explaining a range of physical and psychological disorders. Even though the core symptoms of schizophrenia, depression and many other psychiatric disorders have often been reported to be universal, the cultural influences on presentation can be important in non-Westernised societies. Nevertheless, even with the acknowledged influence of cultural factors on psycho-pathology, many professionals still fail to adopt an appropriate cultural perspective when dealing with these quasi-psychologically abnormal persons.

One has to be particularly wary if the patient has a religious background such as Buddhism or Taoism, the tenets of which accommodate the existence of gods and spirits, or an exposure to an environment that nurtures the mystic or the occult, or simply an avid quest for supernatural phenomena. This has implications because whereas in westernized countries delusional ideas may be seen as pathological or abnormal negative experiences, in societies or communities where such experiences are looked upon as spiritual, positive and acceptable, this may be a different matter. Popular religion with recognition of gods (神shen) and spirits (鬼kuei) is very much alive in the daily life of many people.^6-9 It has to be borne in mind that a Chinese patient might not proclaim to have a religious creed, yet s/he could still fully accept the existence of supernatural or spiritual beings. Of course, the very presence of a religious faith does not necessarily exclude real mental illness. In this event, the occurrence of religious ideas in individual delusional systems can be explained on the basis of exposure to religious ideas through social learning. It may also be related to the prominence of religion, vis--vis other belief systems in the culture. Individual psychodynamics determine the appearance of symptoms, but their particular form will be the result of these background factors, one of which is religion.¹⁰

From a different perspective, the cognitive approach to the situation takes the position that what the patient said about the demon was her attribution of her malaise.^11-13 In other words, this is her way of finding an acceptable explanation of the occurrence, in an endeavour to make sense of her experience and perhaps to find some solace.

At the time of consultation, a question may occur to the clinician: should she be treated? It makes good clinical sense that, in the absence of other cardinal or full-blown psychotic symptoms, it would be sapient to wait and observe; that is to practice watchful waiting.

In the final analysis, an astute clinician will always allow a possibility, however slim, of the 'patient', or just a worried-well person with an unheeded yet benign fear which instantly becomes a symptom in the surgery on the assumption that a patient must have symptom(s), thus allowing obscure complaints to justify the label of patienthood on the ground that these might harbinger dire consequences.

Indeed, a reassuring explanation and appropriate health education may go a long way towards fostering a sense of well-being in the worried person by preventing a spurious medical label at the budding stage of symptom-formation. Ascribing the experience to a nightmare, rather than calling it a symptom, might be the softest option for the clinician dealing with the consultation. After all, except in rare circumstances, sleep paralysis seldom occurs sequentially night after night. In the event of continued presence of sleep paralysis over a period of weeks, which is relatively rare in practice, it is worth a short trial of REM suppressant such as benzodiazepines. Often, the anxiety and fear engendered as a consequence are more difficult to manage than the primary complaint itself.

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