تجربیات مربوط به خواب چه چیزی هستند؟ ارتباط با پریشانی روانی و استرس زندگی

Sleep-related experiences [Watson, D. (2001). Dissociations of the night: Individual differences in sleep-related experiences and their relation to dissociation and schizotypy. Journal of Abnormal Psychology, 110, 526–535] refer to a host of nocturnal altered-consciousness phenomena, including narcoleptic tendencies, nightmares, problem-solving dreams, waking dreams, and lucid dreams. In an attempt to clarify the meaning of this construct, we examined cross-sectional and longitudinal associations of sleep-related experiences (SREs), altered-consciousness tendencies (i.e., dissociation and transliminality), psychological distress, childhood maltreatment (i.e., abuse and neglect), and life stress in young adults. Both types of SREs (general SREs and lucid dreaming) were found to be distinguishable from altered-consciousness tendencies. Transliminality emerged as a longitudinal predictor of both general SREs and lucid dreams. Psychological distress and an increase in life stress predicted an increase in general SREs over a 3-month interval. We conclude that transliminality is a general altered-consciousness trait that accounts for some of the individual differences in sleep-related experiences, and that general sleep experiences are an outcome of psychological distress and life stress.

Watson (2001) proposed a fascinating—and relatively understudied—construct, labeled sleep-related experiences (SREs). This construct includes a variety of nocturnal altered-consciousness phenomena, such as nightmares, narcoleptic characteristics, recurring dreams, dream recall, vivid dreams, problem-solving dreams, dreams confused with reality (“waking dreams”), and lucid dreams. Although these different phenomena are rather diverse experiences, Watson showed that, apart from lucid dreaming (LD), the rest of these experiences constitute a single psychological construct, labeled general sleep experiences (GSEs). The purpose of the present study is to elucidate the nature of sleep-related experiences (SREs) by way of locating this construct in the context of key clinical factors, namely psychological distress, altered-consciousness tendencies (dissociation and transliminality), and traumatic and life stress. Unlike previous research, which has mainly been based on cross-sectional designs, in the present study we utilized a longitudinal design, thereby increasing our ability to examine the direction of relationships between the aforementioned constructs. An additional strength of this study’s design is the inclusion of scales that have yet to be administered concurrently, such as transliminality and sleep experiences. 1.1. Previous research Nightmare frequency is a well-researched SRE, presumably due to its importance in post-traumatic-stress disorder and general psychopathology (e.g., Chivers and Blagrove, 1999, Cukrowicz et al., 2006, Mellman et al., 2001 and Nguyen et al., 2002). It is also the main criterion for diagnosis of nightmare disorder in the DSM-IV ( American Psychiatric Association [APA], 1994). A general estimate of annual nightmare frequency lies in the range of 11.04–41.7 nightmares per year, depending on nightmare definition ( Chivers and Blagrove, 1999 and Zadra and Donderi, 2000). Furthermore, at least four percent of the population report that they regularly have nightmares ( Levin and Nielsen, 2007 and Stepansky et al., 1998). Narcolepsy is a REM-related sleep disorder, in which some symptoms are common among normal population ( Cheyne and Girard, 2007, Cheyne et al., 1999, Jakes and Hemsley, 1987, Ohayon, 2000 and Ohayon et al., 1996). Such widespread symptoms include sleep paralysis (a conscious state in which there is inability to move prior to falling asleep or upon awakening), and vivid hypnagogic or hypnopompic hallucinations (hallucinatory sensory experiences occurring at sleep onset or offset; Cheyne et al., 1999 and Kryger et al., 2000). These hallucinations may be visual, auditory, kinesthetic (e.g., sensations such as falling or floating, sometimes experienced as out-of-body-experiences), or of another type (e.g., sensing the presence of an external agent; Girard and Cheyne, 2004 and Ohayon, 2000). Recurring dreams are dreams that repeat over time while maintaining the same theme and content across repetitions ( Brown and Donderi, 1986, Heaton et al., 1998 and Zadra et al., 2006). These dreams should be differentiated from post-traumatic repetitive dreams, in which an actual traumatic event is replayed accurately within the dream ( Hartmann, 1998). However, even when taking this distinction into consideration, recurring dreams have usually been found to be associated with negative dream content or emotions, or low psychological well-being ( Brown and Donderi, 1986, Robbins and Houshi, 1983, Zadra et al., 1998 and Zadra et al., 2006). Dream recall is the tendency to remember dreams. In a sample of one thousand Austrians, Stepansky et al. (1998) found that 68% of participants reported remembering at least one dream a month. However, the frequency of recalling dreams varies to a great extent among different individuals ( Schredl, 2004). This trait, which has been widely studied, perhaps since it is easily measured, has been correlated with various biological, state, and trait factors (for a review see: Schredl & Montasser, 1996; but see Beaulieu-Prevost and Zadra, 2007 and Hartmann and Kunzendorf, 2007). Finally, a lucid dream is a dream in which one is aware that one is dreaming, and can often control the dream events or content ( Blagrove and Hartnell, 2000, LaBerge and DeGracia, 2000, Schredl and Erlacher, 2004 and Vaitl et al., 2005). Estimations of the percent of lucid dreamers in the population are various and lie between 26% and 82% (e.g., Schredl and Erlacher, 2004, Snyder and Gackenbach, 1988 and Stepansky et al., 1998). The different types of dreams and nocturnal experiences described above may all be construed as “dissociations of the night” (Watson, 2001) or in other words, nocturnal altered-consciousness phenomena. Thus, it may be useful to investigate their common features or shared characteristics. Watson, 2001 and Watson, 2003 developed a preliminary version of the Iowa Sleep Experiences Survey, a 19-item questionnaire, the aim of which was to assess these phenomena as well as other, less studied, nocturnal altered-consciousness experiences (such as problem-solving dreams, vivid dreams, and “waking dreams”—dreams confused with reality). A principal component analysis revealed that a general factor accounts for sleep experiences best. Further developing the ISES, Watson (2001) reported that it is based on two factors: a 15-item general sleep experiences factor (GSE), and a 3-item lucid dreams factor (LD). To the best of our knowledge, the ISES is the only reliable and valid measure of a wide range of nocturnal altered-consciousness experiences. 1.2. Conceptualization and empirical research Watson (2001) construed SREs as “dissociations of the night”, and demonstrated a relationship between SREs, trait dissociation, and schizotypy in a non-clinical population. Two possible, and at times contradicting, conceptualizations of SREs may be derived from his work: first, the use of a dissociation measure suitable for assessing trait dissociation in a non-clinical population, and indeed, the administration of this measure in such a population, imply a conceptualization of SREs as a nocturnal altered-consciousness trait which is not necessarily psychopathological. Second, the association of SREs with schizotypy and dissociation suggests a conceptualization of SREs as manifestations of psychopathology. In what follows, both perspectives will be reviewed, alongside supportive empirical findings. The first conceptualization, namely that of SREs as a nocturnal altered-consciousness trait, is based on the association found between SREs and trait dissociation in a non-clinical population (Watson, 2001, see also Fassler et al., 2006, Giesbrecht and Merckelbach, 2004 and Giesbrecht and Merckelbach, 2006). Moreover, item-based analyses of the ISES reveal that nearly all of the different SRE items are significantly correlated with trait dissociation (Watson, 2001). In fact, the only item not significantly correlated with dissociation is dream recall. However, dream recall was associated with dissociative scales in later analyses (Watson, 2003). Specific SREs have been shown to correlate with trait dissociation in other studies as well. For example, chronic nightmare sufferers obtained higher dissociation scores in a sample of undergraduate students (Agargun et al., 2003). A further link between specific SREs and dissociative tendencies may be found in the association between out-of-body experiences and lucid dreaming (for a review see Irwin, 1988). In addition, out-of-body experiences may be viewed as possible manifestations of a hypnagogic or hypnopompic hallucination (Girard and Cheyne, 2004 and Ohayon, 2000). Watson (2001) suggested that the mechanism underlying the association between SREs and dissociative tendencies might be a personality trait, which determines the relative ease vs. difficulty with which psychological material can shift between different states of consciousness. Constructs aiming to measure this hypothetical trait are Hartmann, 1991 and Hartmann, 1998 “boundaries” concept, as well as Thalbourne and Houran’s (2000) notion of “transliminality”—a hypothesized tendency for psychological material to cross thresholds into or out of consciousness. Such a tendency would most likely induce dissociative states such as dissociative amnesia or out-of-body experiences, as well as SREs such as lucid dreaming or hypnagogic hallucinations. In fact, transliminality has been found to correlate both with depersonalization ( Thalbourne, Crawley, & Houran, 2003) and with dream recall ( Thalbourne & Delin, 1999), nightmares, and lucid dreams ( Lange, Thalbourne, Houran, & Storm, 2000). However, to the best of our knowledge, Watson’s hypothesis that transliminality might account for SREs has not been directly tested. This was one of the objectives of the present study. Note that implicit in the above reviewed theory and research on the link between dissociation and SREs is the notion that the former causes the latter. However, an alternative explanation of this link is that dissociation and SREs are essentially two manifestations of altered consciousness. Indeed, the considerable shared variance found between these two constructs raises questions as to the extent to which they are distinct. In the event that they are not, the examination of directional relationships is untenable. Therefore, before examining directional relationships between these constructs, the present study will evaluate the extent to which SREs are distinguishable from dissociation and transliminality. A second attempt at conceptualization derived from Watson (2001) is that of SREs as a manifestation of psychopathology. Watson (2001) found that SREs are related to schizotypal tendencies, while Fassler et al. (2006) reported a relationship between SREs and negative affect. In addition, specific SREs were found to be associated with dissociation on a pathological level. For example, Schenck, Milner, Hurwitz, Bundlie, and Mahowald (1989) found that of 150 patients at a sleep disorder clinic, over 5% had multiple personality disorder (currently labeled Dissociative Identity Disorder), or were close to fulfilling the criteria, while estimates of this disorder in the general population lie between 1 and 2 percent (Casey, 2001 and Loewenstein, 1994). Another link between pathological dissociation and nocturnal experiences is the high rate of nightmare disorder found among patients diagnosed with Dissociative Identity Disorder (DID) (Agargun et al., 2003). Furthermore, sleep-related eating disorder (Schenck & Mahowald, 1994), a syndrome in which binge eating takes place during the night and is accompanied by (partial) amnesia of the episode on the following day, and which might be viewed as a nocturnal dissociation episode, was found to be correlated with both dissociation and nightmares (Winkelman, Herzog, & Fava, 1999). Although the role of psychopathology has been widely studied in some specific SREs, such as nightmares (e.g., Cukrowicz et al., 2006), most SREs, for instance, lucid dreams, waking dreams, or problem-solving dreams, are not typically considered psychopathological, and therefore their possible relation to psychopathology or psychological distress has not been studied. Cognizant of this gap in the literature, we set out to examine the longitudinal predictive effect of psychological distress on sleep-related experiences as a whole. Herein we also examined the role of traumatic and life stress in SREs. Childhood trauma, particularly child maltreatment, has been repeatedly shown to be associated with dissociation (e.g., Irwin, 1994, Noll et al., 2003, Ogawa et al., 1997 and Sanders and Giolas, 1991), and therefore might be involved in SREs as well. Another important link between SREs and trauma is the major role played by nightmares in Post-Traumatic Stress Disorder (PTSD, e.g., Esposito et al., 1999 and Mellman et al., 2001). Additionally, stressful life events might be implicated in SREs because they predict nightmares and recurrent dreams ( Brown and Donderi, 1986, Robbins and Houshi, 1983, Schredl, 2003 and Zadra and Donderi, 2000). Furthermore, in extreme situations acute stress has been shown to predict dissociative symptoms ( Morgan et al., 2001). Finally, consistent with the stress-diathesis model (e.g., Monroe & Simons, 1991), we also examined the possibility that stressful life events interact with internal characteristics, such as psychological distress or altered-consciousness tendencies to predict sleep experiences. To summarize, in order to elucidate the nature of SREs, we set out to: 1. Evaluate the extent to which SREs are distinguishable from dissociation and transliminality. 2. Examine cross-sectional and longitudinal associations between SREs on the one hand, and dissociation and transliminality (to the extent that the latter are distinct from SREs), psychological distress, childhood trauma, and life stress, on the other.