Dream-enacting behaviors in a normal population

Penumbral thoughts: Contents of consciousness upon waking

Thoughts shape our experience, choice, and behaviour throughout the day. Yet the content of 'penumbral thoughts'-first thoughts upon waking-has received very little research attention. Across seven independent samples (total N = 829), we used recall and reflection methods, solicited the same day, to understand what individuals think as they regain consciousness. These penumbral thoughts show remarkable thematic consistency: individuals were most likely to reflect on their somatic or psychological state, focus on temporal orientation, and prioritise waking actions. Survey results demonstrate that temporal and spatial orientation are dominated by the current time and the day ahead, rather than the past or other future timescales. Our results provide some insight into the order of priority in consciousness. We conclude that establishing one's temporal position is important to the daily process of 'rebooting' conscious awareness.

[Analysis of causes or reasons that fragment sleep and sleep disorder in pregnant and non-pregnant women]

Introduction

During pregnancy, sleep undergoes important changes. The objective was to assess the causes or reasons that fragment sleep and sleep disorders in different women and trimesters of pregnancy, comparing them with those of non-pregnant women (NPW).

Methods

Cross-sectional study. Anonymous surveys were used to evaluate reasons that fragment sleep and specific questionnaires to evaluate sleep disorders. Results: Pregnant Women (PW)= 320. 1st Trimester of pregnancy (T): n = 106, 2nd. T: n = 104, 3rd T: n = 110. MNE: n = 304. Most frequent reasons that fragmented sleep, statistically significant in PW and were: need to urinate, uncomfortable position, not being able to rotate in bed. As sleep disorders we find: nightmares 44 vs 4.9%; snoring with pauses: 31 vs 3%.

Conclusion

We found that in the PW studied, most of the causes or reasons analyzed fragmented sleep; they had more sleep disorders such as nightmares, respiratory disorders and periodic leg movements, in that order, compared to the NPW who in turn, presented insomnia, excessive sleepiness and bruxism.

Isolated dream‐enactment behaviours as a prodromal hallmark of rapid eye movement sleep behaviour disorder

Recurrent dream-enactment behaviours (DEB) and rapid eye movement (REM) sleep without atonia (RSWA) are two diagnostic hallmarks of REM sleep behaviour disorder (RBD), a specific prodrome of α-synucleinopathy. Whilst isolated RSWA (without DEB) was suggested as a prodrome of RBD, the implication of 'isolated' recurrent DEB remains under-investigated. In this cross-sectional study, we sought to investigate neurodegenerative markers amongst the first-degree relatives (FDRs, aged >40 years) of patients with RBD who underwent clinical assessment for DEB, neurodegenerative markers, and video-polysomnography assessment. Isolated recurrent DEB was defined as: (i) three or more episodes of DEB, (ii) had a DEB episode in the past 1 year, and (iii) subthreshold RSWA. We identified 29 FDRs (mean [SD] age 53.4 [8.3] years, 55.2% male) with isolated recurrent DEB and 98 age and sex-matched FDRs as controls. Isolated DEB was associated with nightmare (27.6% versus 11.2%, p = 0.02), and the DEB group had a higher rate of current smoking (27.6% versus 3.1%, p = 0.006), type 2 diabetes mellitus (24.1% versus 10.2%, p = 0.003), anxiety disorder (24.1% versus 11.2%, p = 0.02), and constipation (hard lump of stool, 31.0% versus 7.1%, p < 0.001) than the control group. The present findings revealed that family relatives of patients with RBD with isolated recurrent DEB have increased risk of RBD and neurodegenerative features, which adds to the emerging data that isolated DEB is a prodromal feature of RBD and α-synucleinopathy neurodegeneration.

SARS-CoV-2 infection is associated with increased odds of insomnia, RLS and dream enactment behavior

BACKGROUND

Literature suggests that the COVID-19 pandemic has resulted in poor sleep quality, especially among the infected population. However, literature regarding the effect of COVID-19 pandemic and SARS-CoV-2 infection on occurrence of insomnia, restless legs syndrome and dream enactment behavior is either scarce or unavailable.

METHODS

This study was planned to assess the effect of SARS-CoV-2 infection on the occurrence of insomnia, restless legs syndrome (RLS) and dream enactment behavior (DEB). For this cross-sectional study, a questionnaire comprising of items related to demographic details, past medical history, and information related to SARS-CoV-2 infection was distributed through social media. Insomnia was diagnosed using clinical criteria. RLS, DEB, sleep quality, depression and anxiety were assessed using a validated questionnaire. Information regarding the use of hypnotic medications was also gathered.

RESULTS

Of the 1596 respondents, 37.2% reported disturbed sleep while insomnia was reported by 22.6% respondents. 27.3% of respondents reported RLS and 17.4% suffered DEB. The odds of insomnia were greater among males (OR = 1.27; 95% CI: 1.03-1.58; P < 0.02) and among those who had SARS-CoV-2 infection (OR = 1.76; 95% CI = 1.42-2.19; P < 0.001). Similarly, SARS-CoV-2 infection was also associated with increased odds of RLS (OR = 2.48; 95% CI = 1.98-3.11; P < 0.001) and DEB (OR = 1.58; 95%CI = 1.21-2.06; P < 0.001). Insomnia, RLS and DEB were more frequent among respondents who required oxygen therapy, those who experienced loss of taste and/or smell, depression and anxiety. Prevalence of insomnia, DEB and RLS was higher than said prevalence among respondents with no history of SARS-CoV-2 infection, but lower than that of those with positive history of SARS-CoV-2 infection. 5.3% of respondents reported taking hypnotic medications before infection, 7% during infection and 5.3% after infection.

CONCLUSION

SARS-CoV-2-infection-related factors in association with environmental factors have increased the prevalence of insomnia, DEB and RLS among subjects having infection. SARS-CoV-2-associated immunological changes, hypoxia and neurotropism may play a role in occurrence of insomnia, DEB and RLS.

Sleep talking versus sleep moaning: electrophysiological patterns preceding linguistic vocalizations during sleep

STUDY OBJECTIVES

Sleep talking (ST) has been rarely studied as an isolated phenomenon. Late investigations over the psycholinguistic features of vocal production in ST pointed to coherence with wake language formal features. Therefore, we investigated the EEG correlates of Verbal ST as the overt manifestation of sleep-related language processing, with the hypothesis of shared electrophysiological correlates with wake language production.

METHODS

From a sample of 155 Highly frequent STs, we recorded 13 participants (age range 19-30 years, mean age 24.6 ± 3.3; 7F) via vPSG for at least two consecutive nights, and a total of 28 nights. We first investigated the sleep macrostructure of STs compared to 13 age and gender-matched subjects. We then compared the EEG signal before 21 Verbal STs versus 21 Nonverbal STs (moaning, laughing, crying, etc.) in six STs reporting both vocalization types in Stage 2 NREM sleep.

RESULTS

The 2 × 2 mixed analysis of variance Group × Night interaction showed no statistically significant effect for macrostructural variables, but significant main effects for Group with lower REM (%), total sleep time, total bedtime, sleep efficiency index, and greater NREM (%) for STs compared to controls. EEG statistical comparisons (paired-samples Student's t-test) showed a decrement in power spectra for Verbal STs versus Nonverbal STs within the theta and alpha EEG bands, strongly lateralized to the left hemisphere and localized on centro-parietal-occipitals channels. A single left parietal channel (P7) held significance after Bonferroni correction.

CONCLUSIONS

Our results suggest shared neural mechanisms between Verbal ST and language processing during wakefulness and a possible functional overlapping with linguistic planning in wakefulness.

What about dreams? State of the art and open questions

Several studies have tried to identify the neurobiological bases of dream experiences, nevertheless some questions are still at the centre of the debate. Here, we summarise the main open issues concerning the neuroscientific study of dreaming. After overcoming the rapid eye movement (REM) ‐ non‐REM (NREM) sleep dichotomy, investigations have focussed on the specific functional or structural brain features predicting dream experience. On the one hand, some results underlined that specific trait‐like factors are associated with higher dream recall frequency. On the other hand, the electrophysiological milieu preceding dream report upon awakening is a crucial state‐like factor influencing the subsequent recall. Furthermore, dreaming is strictly related to waking experiences. Based on the continuity hypothesis, some findings reveal that dreaming could be modulated through visual, olfactory, or somatosensory stimulations. Also, it should be considered that the indirect access to dreaming remains an intrinsic limitation. Recent findings have revealed a greater concordance between parasomnia‐like events and dream contents. This means that parasomnia episodes might be an expression of the ongoing mental sleep activity and could represent a viable direct access to dream experience. Finally, we provide a picture on nightmares and emphasise the possible role of oneiric activity in psychotherapy. Overall, further efforts in dream science are needed (a) to develop a uniform protocol to study dream experience, (b) to introduce and integrate advanced techniques to better understand whether dreaming can be manipulated, (c) to clarify the relationship between parasomnia events and dreaming, and (d) to determine the clinical valence of dreams.

Predictors of dream enactment behavior among medical students: The case of the University of Gondar, Ethiopia

INTRODUCTION

Dream enactment behavior is one of the features of rapid eye movement sleep behavior disorder. It might be a manifestation of neurodegenerative diseases and can lead to fall associated injuries. There is no evidence of dream enactment behavior and its associated factors in Ethiopia. Hence, this study targeted to pinpoint the predictors of dream enactment behavior among Medical students at the University of Gondar.

METHODS

The cross-sectional survey was carried out at the University of Gondar among Medical students selected by simple random sampling technique from Dec 2020 to Feb 2021. We used a structured pretested questionnaire to collect the data and dream enactment behavior was evaluated using rapid eye movement sleep behavior disorder single question. Descriptive statistics were computed, and determinant factors were identified using binary logistic regression model. In the final model, explanatory variables with a p<0.05 were considered as predictors (statistically significant) of the dream enactment behavior. The strength of association was determined using adjusted odds ratio (AOR) with its 95% CI.

RESULTS

Four-hundred and twelve students took part in the study with 97.4% response rate. The mean age of participants was 20.82(±1.88) years and 291(70.63%) were males. The prevalence of dream enactment was 34.47% (95% CI: 30.02-39.20). Daytime sleepiness score (AOR = 1.104; 95% CI: 1.053-1.160), age (AOR = 1.15; 95% CI: 1.019-1.290), monthly pocket money (AOR = 0.9991; 95% CI: 0.9985-0.9997), alcohol drink (AOR = 2.71; 95% CI: 1.076-6.846), and perceived stress (AOR = 3.854; 95% CI: 1.802-8.242) were statistically significant factors of dream enactment behavior.

CONCLUSIONS

In this study, the magnitude of dream enactment behavior was high which was significantly associated with daytime sleepiness score, age, monthly pocket money, alcohol drink, and perceived stress all of which are modifiable except age. The University of Gondar has to plan a strategy to avert the condition via the prevention of the determinant factors. Students need to reduce stress and avoid alcohol drink. We strongly urge forthcoming scholars to ascertain association of dream enactment and academic performance of university students.

Early impact on sleep and mental health during the mandatory social isolation of COVID-19 outbreak: an obser vational cross-sectional study carried out in Argentina

Introduction

The mandatory social isolation (MSI) due to the pandemic caused by COVID-19 in the world produced many changes in sleep and different areas of mental health. Objectives: To evaluate the early effects of MSI on sleep, anxiety, and depression in Argentina.

Material and Methods

An anonymous observational cross-sectional web-based study was distributed throughout the country and was completed by 2,594 respondents to analyze demographic information, quality of sleep, REM sleep-related events, depressive, and anxiety symptoms.

Results

The study revealed that 53, 21, 22, 23, and 16% of people surveyed were poor sleepers, had dream-related behaviors, nightmares, depression, and anxiety symptoms, respectively. Multivariate logistic regression showed a positive correlation between anxiety, being a poor sleeper, and having nightmares.

Conclusion

We identified the early effects of MSI on sleep quality, dreaming activity, anxiety, and depression in Argentina during the COVID-19 outbreak. Our findings can be used to formulate sleep and psychological interventions to improve mental health during the pandemic and post-pandemic times.

Do animals dream?

The understanding of biological functions of sleep has improved recently, including an understanding of the deep evolutionary roots of sleep among animals. However, dreaming as an element of sleep may be particularly difficult to address in non-human animals because in humans dreaming involves a non-wakeful form of awareness typically identified through verbal report. Here, we argue that parallels that exist between the phenomenology, physiology, and sleep behaviors during human dreaming provide an avenue to investigate dreaming in non-human animals. We review three alternative measurements of human dreaming - neural correlates of dreaming, 'replay' of newly-acquired memories, and dream-enacting behaviors - and consider how these may be applied to non-human animal models. We suggest that while animals close in brain structure to humans (such as mammals and birds) may be optimal models for the first two of these measurements, cephalopods, especially octopuses, may be particularly good candidates for the third.

Clinical Correlates of Dream Enactment Behaviors in Previously Deployed OEF/OIF/OND Veterans: An Exploratory Analysis

OBJECTIVE

Veterans with posttraumatic stress disorder (PTSD) frequently report dream enactment behavior (DEB). Although DEBs are associated with PTSD symptoms, their relationship with other sleep disorders, including REM behavior disorder, warrants reexamination of their clinical correlates.

METHODS

The investigators used a cross-sectional, exploratory analysis to compare demographic and clinical characteristics of veterans endorsing regularly occurring DEB compared with those endorsing no or infrequent DEB. The participants comprised a convenience sample of servicemembers who were previously deployed to Operation Enduring Freedom/Operation Iraqi Freedom/Operation New Dawn (OEF/OIF/OND) and enrolled in an ongoing cohort study.

RESULTS

Of the 78 eligible participants, 19 (24.4%) endorsed DEBs occurring at least once per week in the past month. Compared with participants who reported no or infrequent DEBs, participants with regularly occurring DEBs had poorer sleep quality, greater PTSD severity, a higher number of reported mild traumatic brain injuries (mTBI) with loss of consciousness, and a higher likelihood of being diagnosed with sleep disorders. After adjustment for global sleep quality, a significant association persisted between DEBs and the number of mTBI with loss of consciousness but not between DEBs and the severity of PTSD symptoms.

CONCLUSIONS

These results suggest that mTBI may disrupt neural circuits regulating sleep among OIF/OEF/OND veterans. Prospective, polysomnographic assessment of muscle tone and behavioral events during REM sleep is needed to characterize the physiology of DEBs in this population.

Dream enactment behavior: review for the clinician

NONE

Dream enactment behavior commonly occurs on occasion in normal children and adults. Disruptive and frequent dream enactment behavior may come to the attention of the clinician either as the primary reason for consultation or as a prominent characteristic of a patient with other sleep disorders. Questioning patients with chronic neurologic and psychiatric disorders may also reveal previously unrecognized behavior. In the absence of sleep pathology, process of dream enactment likely begins with active, often emotionally charged dream content that may occasionally break through the normal REM sleep motor suppressive activity. Disrupted sleep resulting from many possible causes, such as circadian disruption, sleep apnea, or medications, may also disrupt at least temporarily the motor-suppressive activity in REM sleep, allowing dream enactment to occur. Finally, pathological neurological damage in the context of degenerative, autoimmune, and infectious neurological disorders may lead to chronic recurrent and severe dream enactment behavior. Evaluating the context, frequency, and severity of dream enactment behavior is guided first and foremost by a structured approach to the sleep history. Physical exam and selected testing support the clinical diagnosis. Understanding the context and the likely cause is essential to effective therapy.

A Neurologist's Guide to REM Sleep Behavior Disorder

REM Sleep Behavior Disorder (RBD) is a chronic sleep condition characterized by dream enactment and loss of REM atonia. Individuals often present to clinic with complaints of injury to themselves or their bed-partner due to violent movements during sleep. RBD patients have a high risk of developing one of the neurodegenerative α-synucleinopathy diseases: over 70% will develop parkinsonism or dementia within 12 years of their diagnosis. RBD patients also exhibit accelerated disease progression and a more severe phenotype than α-synucleinopathy sufferers without RBD. The disease's low prevalence and the relatively limited awareness of the condition amongst medical professionals makes the diagnosis and treatment of RBD challenging. Uncertainty in patient management is further exacerbated by a lack of clinical guidelines for RBD patient care. There are no binary prognostic markers for RBD disease course and there are no clinical guidelines for neurodegeneration scaling or tracking in these patients. Both clinicians and patients are therefore forced to deal with uncertain outcomes. In this review, we summarize RBD pathology and differential diagnoses, diagnostic, and treatment guidelines as well as prognostic recommendations with a look to current research in the scientific field. We aim to raise awareness and develop a framework for best practice for RBD patient management.

The Functional Role of Dreaming in Emotional Processes

Dream experience (DE) represents a fascinating condition linked to emotional processes and the human inner world. Although the overlap between REM sleep and dreaming has been overcome, several studies point out that emotional and perceptually vivid contents are more frequent when reported upon awakenings from this sleep stage. Actually, it is well-known that REM sleep plays a pivotal role in the processing of salient and emotional waking-life experiences, strongly contributing to the emotional memory consolidation. In this vein, we highlighted that, to some extent, neuroimaging studies showed that the processes that regulate dreaming and emotional salience in sleep mentation share similar neural substrates of those controlling emotions during wakefulness. Furthermore, the research on EEG correlates of the presence/absence of DE and the results on EEG pattern related to the incorporated memories converged to assign a crucial role of REM theta oscillations in emotional re-processing. In particular, the theta activity is involved in memory processes during REM sleep as well as during the waking state, in line with the continuity hypothesis. Also, the gamma activity seems to be related to emotional processes and dream recall as well as to lucid dreams. Interestingly, similar EEG correlates of DE have been found in clinical samples when nightmares or dreams occur. Research on clinical samples revealed that promoting the rehearsal of frightening contents aimed to change them is a promising method to treat nightmares, and that lucid dreams are associated with an attenuation of nightmares. In this view, DE can defuse emotional traumatic memories when the emotional regulation and the fear extinction mechanisms are compromised by traumatic and frightening events. Finally, dreams could represent a sort of simulation of reality, providing the possibility to create a new scenario with emotional mastery elements to cope with dysphoric items included in nightmares. In addition, it could be hypothesized that the insertion of bizarre items besides traumatic memories might be functional to "impoverish" the negative charge of the experiences.

Sleep and sleep disorders in Franz Kafka's narrative works

OBJECTIVE

As Franz Kafka, one of the most important writers of the 20th century, suffered from severe chronic insomnia disorder and inadequate sleep hygiene that impaired his quality of life, we speculated that sleep disorders would be found in his narrative works.

METHODS

We read Kafka's complete literary works looking for references to sleep and sleep disorders, excluding insomnia.

RESULTS

In Kafka's works, sleeping well and for a long time was used as an allegory of having a pleasant life. We found that some of his characters were disturbed by excessive daytime sleepiness and sleep attacks, circadian rhythm sleep-wake disorders, sleep-related hallucinations, sleep symptoms in the context of heart failure and abnormal sleep behaviors (eg, sleep-talking, sleep-crying, sleep-laughing and dream-enacting motor manifestations). Kafka also recalled a dream where bruxism occurred.

CONCLUSION

Kafka's narrative works contain characters suffering from a wide variety of sleep disorders which in some cases represent autobiographical elements but not in others indicating that he was an astute observer of people, sleep and its disorders. The inclusion of characters suffering from sleep disorders was used by Kafka as a literary resource to enrich his texts.

Risk factors for possible REM sleep behavior disorder: A CLSA population-based cohort study

OBJECTIVE

To assess sociodemographic, socioeconomic, and clinical correlates of idiopathic REM sleep behavior disorder (RBD) in a 30,097-person national cohort.

METHODS

Participants 45 to 85 years of age in Canada were collected as part of the Canadian Longitudinal Study on Aging. Possible RBD (pRBD) was screened with the REM Sleep Behavior Disorder Single-Question Screen, a questionnaire with 94% specificity and 87% sensitivity. To improve diagnostic accuracy, those screening positive for apnea or non-REM parasomnia (young-onset pRBD) and those self-reporting dementia or Parkinson disease were excluded. A series of sociodemographic, lifestyle, and mental health variables were analyzed cross-sectionally. Potential correlates were assessed via multivariable logistic regression.

RESULTS

Of 30,097 participants, 958 (3.2%) were identified as having pRBD. Male sex (odds ratio [OR] 2.09, 95% confidence interval [CI] 1.78-2.44) and lower education (OR 0.95, 95% CI 0.92-0.98) were associated with pRBD. Participants with pRBD had smoked more (pack-years OR 1.01, 95% CI 1.00-1.01) and were more likely to be moderate to heavy drinkers (OR 1.25, 95% CI 1.04-1.51). There was a strong association between pRBD and self-reported antidepressant treatment for depression (OR 2.77, 95% CI 2.23-3.45), psychological distress (OR 1.61, 95% CI 1.44-1.80), mental illness (OR 2.09, 95% CI 1.75-2.49), and posttraumatic stress disorder (OR 2.68, 95% CI 1.97-3.65).

CONCLUSIONS

Our study replicated previous reported associations between pRBD and smoking, low education, and male sex and found previously unreported links with alcohol use and psychological distress. Risk factors for pRBD differ from those previously defined for neurodegenerative synucleinopathies.

Blaming rape on sleep: A psychoanalytic intervention

The governance of sleep sex (or sexsomnia) in the criminal law is a nightmare. Press reports of sleeping, often drunk, men acquitted as automatons of raping adults and children suggest cases are rising. The use of automatism, rather than insanity, in these cases is strong evidence of the immemorial struggle faced by legal psychiatry in appropriately construing unconscious defendants. This paper responds by drawing on well-established psychoanalytic conceptions of unconsciousness to present sexsomnia as dispositional to the defendant. Taking the Freudian concepts of eros and death instinct, it asserts that sexsomniacs are acting on repressed sadistic desires. Accordingly, those on notice of their sexsomnia, who fail to mitigate the risk of further attacks, should be guilty of rape. Reliance on (a reformed) insanity defence - being a denial of responsibility at the time of the offence - undermines the scope of the criminal law to self-responsibilise sexsomniacs against perpetrating unwanted sex.

Sleep talking: A viable access to mental processes during sleep

Sleep talking is one of the most common altered nocturnal behaviours in the whole population. It does not represent a pathological condition and consists in the unaware production of vocalisations during sleep. Although in the last few decades we have experienced a remarkable increase in knowledge about cognitive processes and behavioural manifestations during sleep, the literature regarding sleep talking remains dated and fragmentary. We first provide an overview of historical and recent findings regarding sleep talking, and we then discuss the phenomenon in the context of mental activity during sleep. It is shown that verbal utterances, reflecting the ongoing dream content, may represent the unique possibility to access the dreamlike mental experience directly. Furthermore, we discuss such phenomena within a cognitive theoretical framework, considering both the atypical activation of psycholinguistic circuits during sleep and the implications of verbal 'replay' of recent learning in memory consolidation. Despite current knowledge on such a common experience being far from complete, an in-depth analysis of sleep talking episodes could offer interesting opportunities to address fundamental questions on dreaming or information processing during sleep. Further systematic polysomnographic and neuroimaging investigations are expected to shed new light on the manifestation of the phenomenon and related aspects.

Emotional facial expressions during REM sleep dreams

Although motor activity is actively inhibited during rapid eye movement (REM) sleep, specific activations of the facial mimetic musculature have been observed during this stage, which may be associated with greater emotional dream mentation. Nevertheless, no specific biomarker of emotional valence or arousal related to dream content has been identified to date. In order to explore the electromyographic (EMG) activity (voltage, number, density and duration) of the corrugator and zygomaticus major muscles during REM sleep and its association with emotional dream mentation, this study performed a series of experimental awakenings after observing EMG facial activations during REM sleep. The study was performed with 12 healthy female participants using an 8-hr nighttime sleep recording. Emotional tone was evaluated by five blinded judges and final valence and intensity scores were obtained. Emotions were mentioned in 80.4% of dream reports. The voltage, number, density and duration of facial muscle contractions were greater for the corrugator muscle than for the zygomaticus muscle, whereas high positive emotions predicted the number (R² 0.601, p = 0.0001) and voltage (R² 0.332, p = 0.005) of the zygomaticus. Our findings suggest that zygomaticus events were predictive of the experience of positive affect during REM sleep in healthy women.

REM sleep behaviour disorder: not just a bad dream

Rapid eye movement (REM) sleep behaviour disorder (RBD) is a parasomnia characterised by the loss of the normal atonia during the REM stage of sleep, resulting in overt motor behaviours that usually represent the enactment of dreams. Patients will seek medical attention due to sleep-related injuries or unpleasant dream content. Idiopathic RBD which occurs independently of any other disease occurs in up to 2% of the older population. Meanwhile, secondary RBD is very common in association with certain neurodegenerative conditions. RBD can also occur in the context of antidepressant use, obstructive sleep apnoea and narcolepsy. RBD can be diagnosed with a simple screening question followed by confirmation with polysomnography to exclude potential mimics. Treatment for RBD is effective and involves treatment of underlying causes, modification of the sleep environment, and pharmacotherapy with either clonazepam or melatonin. An important finding in the past decade is the recognition that almost all patients with idiopathic RBD will ultimately go on to develop Parkinson disease or dementia with Lewy bodies. This suggests that idiopathic RBD represents a prodromal phase of these conditions. Physicians should be aware of the risk of phenoconversion. They should educate idiopathic RBD patients to recognise the symptoms of these conditions and refer as appropriate for further testing and enrolment into research trials focused on neuroprotective measures.

Does Consciousness Disappear in Dreamless Sleep?

Consciousness is often said to disappear in deep, dreamless sleep. We argue that this assumption is oversimplified. Unless dreamless sleep is defined as unconscious from the outset there are good empirical and theoretical reasons for saying that a range of different types of sleep experience, some of which are distinct from dreaming, can occur in all stages of sleep. We introduce a novel taxonomy for describing different kinds of dreamless sleep experiences and suggest research methods for their investigation. Future studies should focus on three areas: memory consolidation, sleep disorders, and sleep state (mis)perception. Our proposal suggests new directions for sleep and dream science, as well as for the neuroscience of consciousness, and can also inform the diagnosis and treatment of sleep disorders.

Idiopathic rapid eye movement sleep behaviour disorder: diagnosis, management, and the need for neuroprotective interventions

Idiopathic rapid eye movement (REM) sleep behaviour disorder (IRBD) manifests as unpleasant dreams and vigorous behaviours during REM sleep that can result in injuries. Patients with IRBD have no known neurological diseases or motor or cognitive complaints; however, this sleep disorder is not harmless. In most cases, IRBD is the prelude of the synucleinopathies Parkinson's disease, dementia with Lewy bodies, or, less frequently, multiple system atrophy. Patients can show abnormalities that are characteristic of the synucleinopathies, and longitudinal follow-up shows that most patients develop parkinsonism and cognitive impairments with time. Thus, diagnosis of IRBD needs to be accurate and involves informing the patient of the risk of developing a neurodegenerative disease. It is extraordinary for a sleep disorder to precede the full expression of a neurodegenerative disease, which renders IRBD of particular interest in studies of the prodromal stage of the synucleinopathies, and in the development of neuroprotective interventions to stop or slow neurodegenerative deterioration before motor and cognitive symptomatology emerges. Such therapeutics do not currently exist, and thus represent an unmet need in IRBD.

Sleep in a legal context: The role of the expert witness

Sleep experts are called to assist the jury in deciding the mental state of the accused at the time of their alleged criminal behaviour. This task is difficult as the literature on many sleep disorders, particularly sleepwalking and other parasomnias, is still largely a matter of case reports and case series. The probative value of much of the evidence given is not known. Sleep behaviour in the courts present a number of difficulties which illustrate the dilemmas that face an expert witness faced with ambiguous data and uncertain principles with which to interpret them. Additionally there are substantial policy issues involved which are not always adequately addressed in expert evidence. We outline the role of expert witnesses in such cases.

Tickle me, I think I might be dreaming! Sensory attenuation, self-other distinction, and predictive processing in lucid dreams

The contrast between self- and other-produced tickles, as a special case of sensory attenuation for self-produced actions, has long been a target of empirical research. While in standard wake states it is nearly impossible to tickle oneself, there are interesting exceptions. Notably, participants awakened from REM (rapid eye movement-) sleep dreams are able to tickle themselves. So far, however, the question of whether it is possible to tickle oneself and be tickled by another in the dream state has not been investigated empirically or addressed from a theoretical perspective. Here, we report the results of an explorative web-based study in which participants were asked to rate their sensations during self-tickling and being tickled during wakefulness, imagination, and lucid dreaming. Our results, though highly preliminary, indicate that in the special case of lucid control dreams, the difference between self-tickling and being tickled by another is obliterated, with both self- and other produced tickles receiving similar ratings as self-tickling during wakefulness. This leads us to the speculative conclusion that in lucid control dreams, sensory attenuation for self-produced tickles spreads to those produced by non-self dream characters. These preliminary results provide the backdrop for a more general theoretical and metatheoretical discussion of tickling in lucid dreams in a predictive processing framework. We argue that the primary value of our study lies not so much in our results, which are subject to important limitations, but rather in the fact that they enable a new theoretical perspective on the relationship between sensory attenuation, the self-other distinction and agency, as well as suggest new questions for future research. In particular, the example of tickling during lucid dreaming raises the question of whether sensory attenuation and the self-other distinction can be simulated largely independently of external sensory input.

Ontogeny of dreaming: a review of empirical studies

The examination of children's sleep-related mental experiences presents many significant challenges for researchers investigating the developmental trajectories of human dreaming. In contrast to the well-explored developmental patterns of human sleep, data from dream research are strikingly divergent with highly ambiguous results and conclusions, even though there is plenty of indirect evidence suggesting parallel patterns of development between neural maturation and dreaming. Thus results from studies of children's dreaming are of essential importance not only to enlighten us on the nature and role of dreaming but to also add to our knowledge of consciousness and cognitive and emotional development. This review summarizes research results related to the ontogeny of dreaming: we critically reconsider the field, systematically compare the findings based on different methodologies, and highlight the advantages and disadvantages of methods, arguing in favor of methodological pluralism. Since most contradictory results emerge in connection with descriptive as well as content related characteristics of young children's dreams, we emphasize the importance of carefully selected dream collection methods. In contrast nightmare-related studies yield surprisingly convergent results, thus providing strong basis for inferences about the connections between dreaming and cognitive emotional functioning. Potential directions for dream research are discussed, aiming to explore the as yet unraveled correlations between the maturation of neural organization, sleep architecture and dreaming patterns.

A scale for assessing the severity of arousal disorders

BACKGROUND

Arousal disorders may have serious health consequences.

OBJECTIVE

To develop a scale assessing the severity of arousal disorders (Paris Arousal Disorders Severity Scale, PADSS).

SETTING

University hospital.

DESIGN

Controlled study.

PARTICIPANTS

Consecutive patients (older than 15 y), with sleepwalking (SW) and/or sleep terrors (ST), subjects with previous SW/ST, normal controls and patients with rapid eye movement sleep behavior disorder.

INTERVENTION

The self-rated scale listed 17 parasomniac behaviors (PADSS-A), assessed their frequency from never to twice or more per night (PADSS-B) and evaluated the consequences (PADSS-C: disturbed sleep, injuries, fatigue, and psychological consequences). The clinimetric properties and face validity of the scale were tested.

RESULTS

Half of the 73 patients with SW/ST (more men than women) had injured themselves or others, whereas 15% had concomitant sexsomnia and 23% had amnestic eating behaviors. The total PADSS score (range: 0-50) was 19.4 ± 6.3 (range: 8-36) in this group, 11.7 ± 5.9 in 26 subjects with previous SW/ST, 8.8 ± 3.2 in 26 patients with RBD, and 2.0 ± 3.5 in 53 normal controls (P < 0.05). The PADSS demonstrated high sensitivity (83.6%), specificity (87.8%), internal consistency, and test-retest reliability (0.79). The best cutoff for the total score was at 13/14. Exploratory factor analysis revealed two components: wandering and violence/handling. The complexity of behaviors emerging from N3 sleep (scored on videopolysomnography) positively correlated with scores for the PADSS-total, PADSS-A, PADSS-C, and the "violence/handling" factor.

CONCLUSION

This scale had reasonable psychometric properties and could be used for screening and stratifying patients and for evaluating the effects of treatments.

Reporting dream experience: Why (not) to be skeptical about dream reports

Are dreams subjective experiences during sleep? Is it like something to dream, or is it only like something to remember dreams after awakening? Specifically, can dream reports be trusted to reveal what it is like to dream, and should they count as evidence for saying that dreams are conscious experiences at all? The goal of this article is to investigate the relationship between dreaming, dream reporting and subjective experience during sleep. I discuss different variants of philosophical skepticism about dream reporting and argue that they all fail. Consequently, skeptical doubts about the trustworthiness of dream reports are misguided, and for systematic reasons. I suggest an alternative, anti-skeptical account of the trustworthiness of dream reports. On this view, dream reports, when gathered under ideal reporting conditions and according to the principle of temporal proximity, are trustworthy (or transparent) with respect to conscious experience during sleep. The transparency assumption has the status of a methodologically necessary default assumption and is theoretically justified because it provides the best explanation of dream reporting. At the same time, it inherits important insights from the discussed variants of skepticism about dream reporting, suggesting that the careful consideration of these skeptical arguments ultimately leads to a positive account of why and under which conditions dream reports can and should be trusted. In this way, moderate distrust can be fruitfully combined with anti-skepticism about dream reporting. Several perspectives for future dream research and for the comparative study of dreaming and waking experience are suggested.

Why are dreams interesting for philosophers? The example of minimal phenomenal selfhood, plus an agenda for future research

This metatheoretical paper develops a list of new research targets by exploring particularly promising interdisciplinary contact points between empirical dream research and philosophy of mind. The central example is the MPS-problem. It is constituted by the epistemic goal of conceptually isolating and empirically grounding the phenomenal property of “minimal phenomenal selfhood,” which refers to the simplest form of self-consciousness. In order to precisely describe MPS, one must focus on those conditions that are not only causally enabling, but strictly necessary to bring it into existence. This contribution argues that research on bodiless dreams, asomatic out-of-body experiences, and full-body illusions has the potential to make decisive future contributions. Further items on the proposed list of novel research targets include differentiating the concept of a “first-person perspective” on the subcognitive level; investigating relevant phenomenological and neurofunctional commonalities between mind-wandering and dreaming; comparing the functional depth of embodiment across dream and wake states; and demonstrating that the conceptual consequences of cognitive corruption and systematic rationality deficits in the dream state are much more serious for philosophical epistemology (and, perhaps, the methodology of dream research itself) than commonly assumed. The paper closes by specifying a list of potentially innovative research goals that could serve to establish a stronger connection between dream research and philosophy of mind.

Effects of rotigotine on Parkinson's disease-related sleep disturbances

INTRODUCTION

Sleep abnormalities are a frequent non-motor symptom and a prominent cause of disability in patients with Parkinson's disease (PD).

AREAS COVERED

This review discusses what is currently known about the characteristics of sleep disturbances in PD patients and attempts to clarify the role of dopaminergic pathways in their pathogenesis as well as the beneficial effect of dopaminergic agents in their treatment. In particular, this review will focus on the effects of transdermal rotigotine on improving PD-related sleep disorders.

EXPERT OPINION

Sleep disturbances are common in PD, and these disturbances can be reduced or resolved, in large part, by preventing or attenuating nocturnal and early morning motor and non-motor symptoms of PD. The studies discussed within this review suggest that sleep disorders are not just a consequence of motor impairment and dopaminergic therapy but are an integral part of the neurodegenerative process of PD. This is supported by the appearance of specific sleep disturbances, which are related to degeneration of the brainstem areas involved in the regulation of sleep/wake states in advance of typical PD symptoms. Development of more detailed diagnostic tools aimed at detecting sleep disturbances and at defining the main causative factors of sleep disturbances in PD will lead to improved treatment of these disturbances.

Nightmare frequency is related to a propensity for mirror behaviors

We previously reported that college students who indicated engaging in frequent dream-enacting behaviors also scored high on a new measure of mirror behaviors, which is the propensity to imitate another person's emotions or actions. Since dream-enacting behaviors are frequently the culmination of nightmares, one explanation for the observed relationship is that individuals who frequently display mirror behaviors are also prone to nightmares. We used the Mirror Behavior Questionnaire (MBQ) and self-reported frequencies of nightmares to assess this possibility. A sample of 480 students, consisting of 188 males (19.2±1.73 years) and 292 females (19.0±1.55 years) enrolled in a first-year university psychology course, participated for course credit. They completed a battery of questionnaires that included the 16-item MBQ, plus an item about nightmare frequency (NMF) in the past 30 days. NMF scores were split to create low, medium, and high NMF groups. MBQ total scores were significantly higher for female than for male subjects, but an interaction revealed that this was true only for Hi-NMF subjects. MBQ Factor 4, Motor Skill Imitation, paralleled this global interaction for females, whereas MBQ Factor 3, Sleepiness/Anger Contagion, was elevated only for Hi-NMF males. Item analyses indicated that Hi- and Med-NMF females scored higher than Lo-NMF females on the 3 items of Factor 4 that reflect voluntary imitation (imitating famous/cartoon voices, being a physically active spectator, and learning new skills by observing), as well as on 2 other items that reflect involuntary imitation (contagious yawning and self-rated empathy). Although Hi- and Lo-NMF males differed most clearly on the sleepiness item of Factor 3, all 3 items on this factor (including anger contagion and contagious yawning) are plausibly associated with perception of and response to social threat. Results provide evidence that among females nightmares are associated with voluntary and involuntary mirror behaviors during wakefulness, while among males nightmares are associated with threat-related mirror behaviors during wakefulness. They thus support the possibility that the association between mirror behaviors and dream-enacting behaviors is due to a common mirror neuron mechanism that underlies mirror behaviors and nightmares and that involves motor, rather than emotional, resonance. These results have implications for understanding the comorbidity of nightmares and other pathological symptoms such as imitative suicidal behaviors, the influence of observational learning on dissociative symptomatology, and the predominance of threat and aggression in the dream enacting behaviors of REM sleep behavior disorder.

REM sleep behavior disorder in the Korean elderly population: prevalence and clinical characteristics

STUDY OBJECTIVES

To examine the prevalence and clinical characteristics of REM sleep behavior disorder (RBD) and subclinical RBD in the Korean elderly population.

DESIGN

A community-based Korean Longitudinal Study on Cognitive Aging and Dementia and time-synchronized video-polysomnography (vPSG) in a laboratory.

SETTING

Sleep laboratory in a university hospital.

PARTICIPANTS

348 individuals aged 60 years or older.

INTERVENTION

N/A.

MEASUREMENTS AND RESULTS

Among 696 subjects who were invited to participate in a vPSG study, 348 completed the vPSG. RBD was diagnosed when subjects showed REM sleep without atonia (RSWA) in the vPSG, and had history of complex and vigorous behaviors during sleep or abnormal REM sleep behaviors in the vPSG. Subjects with RSWA but no abnormal REM sleep behaviors were diagnosed with subclinical RBD. Seven subjects (5 male, 2 female) had RBD, three of whom (1 male, 2 female) had Parkinson disease. Two subjects reported history of sleep-related injury. The crude prevalence of RBD and idiopathic RBD was 2.01% (95% confidence interval [CI] = 0.54% to 3.49%) and 1.15% (95% CI = 0.03% to 2.27%). An age and sex-adjusted prevalence estimate of RBD and idiopathic RBD in the Korean elderly was 2.01% and 1.34%. Eighteen subjects were diagnosed with subclinical RBD, and the prevalence of subclinical RBD was estimated to be 4.95%.

CONCLUSIONS

RBD and subclinical RBD are not rare in the elderly in the community with abnormal REM sleep behaviors of RBD being mild to injurious and violent. The clinical significance and long-term progression of subclinical RBD needs to be further explored, given the prevalence and its possible relation to RBD.

Relationships between non-pathological dream-enactment and mirror behaviors

Dream-enacting behaviors (DEBs) are behavioral expressions of forceful dream images often occurring during sleep-to-wakefulness transitions. We propose that DEBs reflect brain activity underlying social cognition, in particular, motor-affective resonance generated by the mirror neuron system. We developed a Mirror Behavior Questionnaire (MBQ) to assess some dimensions of mirror behaviors and investigated relationships between MBQ scores and DEBs in a large of university undergraduate cohort. MBQ scores were normally distributed and described by a four-factor structure (Empathy/Emotional Contagion, Behavioral Imitation, Sleepiness/Anger Contagion, Motor Skill Imitation). DEB scores correlated positively with MBQ total and factor scores even with social desirability, somnambulism and somniloquy controlled. Emotion-specific DEB items correlated with corresponding emotion-specific MBQ items, especially crying and smiling. Results provide preliminary evidence for cross-state relationships between propensities for dream-enacting and mirror behaviors--especially behaviors involving motor-affective resonance--and our suggestion that motor-affective resonance mediates dream-enactment imagery during sleep and emotional empathy during waking.

Sleep-laughing--hypnogely

OBJECTIVE

To explain relatively common phenomenon of laughing during sleep and help to better define criteria for differentiating between physiological and pathological sleep-laughing.

METHODS

Observational study of patients who underwent a sleep assessment in a referential tertiary health facility.

RESULTS

A total of ten patients exhibited sleep laughing, nine of whom had episodes associated with rapid eye movement (REM) sleep. Also, in one of the patients sleep-laughing was one of the symptoms of REM sleep Behaviour Disorder, and in another patient sleep-laughing was associated with NREM sleep arousal parasomnia.

CONCLUSION

The collected data and review of literature suggests that hypnogely in majority of the cases presents as a benign physiological phenomenon related to dreaming and REM sleep. Typically, these dreams are odd, bizarre or even unfunny for a person when awake. Nevertheless, they bring a sense of mirth and a genuine behavioural response. In a minority of cases, sleep-laughing appears to be a symptom of neurological disorders affecting the central nervous system. In these patients the behavioural substrate differs when compared to physiological laughing, and the sense of mirth is usually absent.

Fight or flight? Dream content during sleepwalking/sleep terrors vs. rapid eye movement sleep behavior disorder

OBJECTIVE

Dreams enacted during sleepwalking or sleep terrors (SW/ST) may differ from those enacted during rapid eye movement sleep behavior disorder (RBD).

METHODS

Subjects completed aggression, depression, and anxiety questionnaires. The mentations associated with SW/ST and RBD behaviors were collected over their lifetime and on the morning after video polysomnography (PSG). The reports were analyzed for complexity, length, content, setting, bizarreness, and threat.

RESULTS

Ninety-one percent of 32 subjects with SW/ST and 87.5% of 24 subjects with RBD remembered an enacted dream (121 dreams in a lifetime and 41 dreams recalled on the morning). These dreams were more complex and less bizarre, with a higher level of aggression in the RBD than in SW/ST subjects. In contrast, we found low aggression, anxiety, and depression scores during the daytime in both groups. As many as 70% of enacted dreams in SW/ST and 60% in RBD involved a threat, but there were more misfortunes and disasters in the SW/ST dreams and more human and animal aggressions in the RBD dreams. The response to these threats differed, as the sleepwalkers mostly fled from a disaster (and 25% fought back when attacked), while 75% of RBD subjects counterattacked when assaulted. The dreams setting included their bedrooms in 42% SW/ST dreams, though this finding was exceptional in the RBD dreams.

CONCLUSION

Different threat simulations and modes of defense seem to play a role during dream-enacted behaviors (e.g., fleeing a disaster during SW/ST, counterattacking a human or animal assault during RBD), paralleling and exacerbating the differences observed between normal dreaming in nonrapid eye movement (NREM) vs rapid eye movement (REM) sleep.

Parasomnias: an updated review

Parasomnias are abnormal behaviors emanating from or associated with sleep. Sleepwalking and related disorders result from an incomplete dissociation of wakefulness from nonrapid eye movement (NREM) sleep. Conditions that provoke repeated cortical arousals, or promote sleep inertia lead to NREM parasomnias by impairing normal arousal mechanisms. Changes in the cyclic alternating pattern, a biomarker of arousal instability in NREM sleep, are noted in sleepwalking disorders. Sleep-related eating disorder (SRED) is characterized by a disruption of the nocturnal fast with episodes of feeding after an arousal from sleep. SRED is often associated with the use of sedative-hypnotic medications; in particular, the widely prescribed benzodiazepine receptor agonists. Recently, compelling evidence suggests that nocturnal eating may in some cases be a nonmotor manifestation of Restless Legs Syndrome (RLS). rapid eye movement (REM) Sleep Behavior Disorder (RBD) is characterized by a loss of REM paralysis leading to potentially injurious dream enactment. The loss of atonia in RBD often predates the development of Parkinson's disease and other disorders of synuclein pathology. Parasomnia behaviors are related to an activation (in NREM parasomnias) or a disinhibition (in RBD) of central pattern generators (CPGs). Initial management should focus on decreasing the potential for sleep-related injury followed by treating comorbid sleep disorders. Clonazepam and melatonin appear to be effective therapies in RBD, whereas paroxetine has been reported effective in some cases of sleep terrors. At this point, pharmacotherapy for other parasomnias is less certain, and further investigations are necessary.

Does rapid eye movement sleep behavior disorder exist in psychiatric populations? A clinical and polysomnographic case-control study

OBJECTIVES

Rapid eye movement (REM) sleep behavior disorder (RBD) has been increasingly reported in patients with psychiatric disorders (pRBD). Although a close association with the usage of psychotropics has been postulated, it remains elusive whether psychotropics are the only causative factor of RBD symptoms in psychiatric populations. Moreover, there is limited literature documenting and quantifying the clinical and polysomnographic features in this population.

METHODS

A case-control study comparing the clinical and polysomnographic features of 31 pRBD patients with: (1) Age-, sex-, and psychiatric diagnoses-matched controls; and (2) Typical idiopathic RBD (tRBD) patients.

RESULTS

Despite being prescribed with similar psychotropics, pRBD patients had more dream-enacting behaviors (p<0.01), sleep-related injuries (p<0.01), and nightmares (p<0.01) than the psychiatric controls. pRBD patients were younger with more females, but they had comparable sleep-related injuries to tRBD. Both tRBD and pRBD had more REM-related muscle activity than controls (p<0.01) and the effect remained significant after adjusting for age, gender, and use of antidepressants.

CONCLUSIONS

Our study suggests that pRBD had comparable clinical features and consequences to those of tRBD. The occurrence of RBD symptoms in these patients may be related to a constellation of factors, including individual predisposition, depressive illness, antidepressants, and other clinical factors. Given the association of RBD and neurodegeneration in tRBD, further prospective follow-up of these patients is warranted.

Diagnostic delay in REM sleep behavior disorder (RBD)

STUDY OBJECTIVES

REM sleep behavior disorder (RBD) is a parasomnia in which normal muscle atonia of REM sleep is lost. The aim of this study was to confirm if diagnostic delay exists in RBD and identify any contributing factors.

METHODS

A database was compiled of 49 patients with RBD seen at a tertiary referral center from 2005 to 2011 by retrospective review of referral letters and polysomnographic (PSG) reports. Patients with comorbid narcolepsy were excluded. A questionnaire was sent to investigate diagnostic delay, management, and comorbidities.

RESULTS

Mean diagnostic delay was 8.7 ± 11 (median 4.5, IQR 1.75-11.75) years in 30 questionnaire responders. Common reasons for diagnostic delay included belief that symptoms were not serious enough to consult a doctor (59%), mild or infrequent occurrence of sleep behavior (56%), belief that symptoms may resolve (47%), and lack of knowledge of treatment options (47%). The bed partner was an important influence, with the decision to seek medical attention being made jointly by the patient and partner in 47%.

CONCLUSIONS

This study has demonstrated the existence of significant diagnostic delay in RBD, mainly due to lack of understanding of the disorder and its treatment by patients and members of the medical profession.

REM sleep behavior disorder: motor manifestations and pathophysiology

Patients with REM sleep behavior disorder (RBD) enact violent dreams during REM sleep in the absence of normal muscle atonia. This disorder is highly frequent in patients with synucleinopathies (60%-100% of patients) and rare in patients with other neurodegenerative disorders. The disorder is detected by interview plus video and sleep monitoring. Abnormal movements expose the patients and bed partners to a high risk of injury and sleep disruption. The disorder is usually alleviated with melatonin and clonazepam. Limb movements are mainly minor, jerky, fast, pseudohallucinatory, and repeated, with a limp wrist during apparently grasping movements, although body jerks and complex violent (fights) and nonviolent culturally acquired behaviors are also observed. Notably, parkinsonism disappears during RBD-associated complex behaviors in patients with Parkinson's disease and with multiple system atrophy, suggesting that the upper motor stream bypasses the basal ganglia during REM sleep. Longitudinal studies show that idiopathic RBD predisposes patients to later develop Parkinson's disease, dementia with Lewy bodies, and, more rarely, multiple system atrophy, with a rate of conversion of 46% within 5 years. During this time window, patients concomitantly develop nonmotor signs (decreased olfaction and color vision, orthostatic hypotension, altered visuospatial abilities, increased harm avoidance) and have abnormal test results (decreased putamen dopamine uptake, slower EEG). Patients with idiopathic RBD have higher and faster risk for conversion to Parkinson's disease and dementia with Lewy bodies if abnormalities in dopamine transporter imaging, transcranial sonography, olfaction, and color vision are found at baseline. They constitute a highly specific target for testing neuroprotective agents.

Prevalence of different parasomnias in the general population

OBJECTIVE

To estimate lifetime and current prevalence (defined as having experienced the specific parasomnia at least once during the last 3 months) of different parasomnias in the general population. In addition, to study the relationship between the different parasomnias and gender, depressive mood, and symptoms of sleep apnea, insomnia and restless legs, as well as estimating the prevalence of having multiple parasomnias.

METHODS

Population based cross-sectional study. One thousand randomly selected adults (51% female), 18years and above, participated in a telephone interview in Norway.

RESULTS

Lifetime prevalence of the different parasomnias varied from about 4% to 67%. For sleep walking lifetime prevalence was 22.4% and current prevalence 1.7%. For the other parasomnias, lifetime and current prevalence were as follows: sleep talking 66.8% and 17.7%, confusional arousal 18.5% and 6.9%, sleep terror 10.4% and 2.7%, injured yourself during sleep 4.3% and 0.9%, injured somebody else during sleep 3.8% and 0.4%, sexual acts during sleep 7.1% and 2.7%, nightmare 66.2% and 19.4%, dream enactment 15.0% and 5.0%, sleep related groaning 31.3% and 13.5%, and sleep-related eating 4.5% and 2.2%. Depressive mood was associated with confusional arousal, sleep terror, sleep-related injury, and nightmare. There were few associations between the parasomnias and gender and symptoms of sleep apnea, insomnia, and restless legs, respectively. About 12% reported having five or more parasomnias.

CONCLUSIONS

This is one of few population based studies investigating the prevalence of parasomnias. Several parasomnias were highly prevalent in the general population. The data need to be interpreted with caution due to methodological issues, i.e., low response rate and single questions.