Antonio Zadra

• PhD
• Professor (Full) at Université de Montréal

Background: Despite its high prevalence, relatively little is known about the pathophysiology of somnambulism. Increasing evidence indicates that somnambulism is associated with functional abnormalities during wakefulness and that sleep deprivation constitutes an important drive that facilitates sleepwalking in predisposed patients. Here, we studi...

Problems with nightmares are reported by a sizable proportion of individuals with a history of trauma and by approximately 5% to 8% of the general population. Chronic nightmares may represent a primary sleep disorder rather than a symptom of a psychiatric disorder, and direct targeting of nightmares is a feasible clinical approach to the problem. O...

Although a potentially helpful therapeutic tool, dream interpretation or dream work is only used occasionally in most forms of psychotherapy. Despite an interest from clinicians and clients alike in using dreams within therapy, many therapists feel unprepared to attend to their clients' dreams. The main goals of this article are to make clinicians...

Somnambulism, or sleepwalking, can give rise to a wide range of adverse consequences and is one of the leading causes of sleep-related injury. Accurate diagnosis is crucial for proper management and imperative in an ever-increasing number of medicolegal cases implicating sleep-related violence. Unfortunately, several widely held views of sleepwalki...

To conduct a comprehensive and comparative study of prospectively collected bad dream and nightmare reports using a broad range of dream content variables. Correlational and descriptive. Participants' homes. Three hundred thirty-one adult volunteers (55 men, 275 women, 1 not specified; mean age = 32.4 ± 14.8 y). N/A. Five hundred seventy-two partic...

Sleepwalking is a common non‐rapid eye movement (NREM) parasomnia and a significant cause of sleep‐related injuries. While evidence suggest that the occurrence of this condition is partly determined by genetic factors, its pattern of inheritance remains unclear, and few molecular studies have been conducted. One promising candidate is the adenosine...

Although emotions are reported in a large majority of dreams, little is known about the factors that account for night-to-night and person-to-person variations in people’s experience of dream affect. We investigated the relationship between waking trait and state variables and dream affect by testing multilevel models intended to predict the affect...

Somnambulism is a non-rapid eye movement sleep parasomnia with potential for significant injury as well as functional nighttime and daytime impairment. Clonazepam is frequently used as first line pharmacotherapy. However, the optimal treatment of somnambulism has not been established. In this article, we present the cases of two patients with sever...

Introduction Sleepwalking is a common arousal parasomnia affecting between 2%-4% of the general adult population. Although factors that intensify or disrupt sleep have been shown to increase the likelihood and intensity of somnambulism in predisposed individuals, little is known about the factors sleepwalkers themselves view as most likely to preci...

Study objectives The present study assessed brain perfusion patterns with single photon emission computed tomography (SPECT) during sleepwalkers’ post-sleep deprivation slow-wave sleep and resting-state wakefulness. Methods Following a 24-hr period of sleep deprivation, 10 sleepwalkers and 10 sex- and age-matched controls were scanned with a high-...

Parasomnias are defined as “disorders characterized by abnormal behavioral, experiential, or physiological events occurring in association with sleep, specific sleep stages, or sleep–wake transitions” in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). The clinical presentation and polysomnographic characteristics, associated fact...

Introduction Several EEG-based studies have documented anomalies in the slow wave sleep (SWS) of adult sleepwalkers. Moreover, previous imaging studies have identified specific brain perfusion patterns in sleepwalkers during post sleep deprivation wakefulness as well as during a somnambulistic episode. However, neuroimaging has yet to be used to in...

Introduction The present study tested a prediction from Levin and Nielsen’s (2007) neurocognitive model of disturbed dreaming stipulating that variations in the frequency of bad dreams and nightmares are partly determined by day-to-day variations in emotional stress. The model also suggests that relations between dreams and stress may vary as a fun...

Study objectives Although sleepwalking (somnambulism) affects up to 4% of adults, its pathophysiology remains poorly understood. Sleepwalking can be preceded by fluctuations in slow-wave sleep EEG signals, but the significance of these pre-episode changes remains unknown and methods based on EEG functional connectivity have yet to be used to better...

While many studies have examined the aetiological underpinnings and psychological correlates of nightmares, very few have focused on laypeople's conceptions of the underlying causes of their own nightmares. The present study investigated laypeople's causal beliefs about their worst nightmare experience and examined whether these beliefs varied as a...

Sleepwalkers often complain of excessive daytime somnolence. Although excessive daytime somnolence has been associated with cognitive impairment in several sleep disorders, very few data exist concerning sleepwalking. This study aimed to investigate daytime cognitive functioning in adults diagnosed with idiopathic sleepwalking. Fifteen sleepwalkers...

Childhood sleepwalking and sleep terrors are 2 parasomnias with a risk of serious injury for which familial aggregation has been shown. To assess the prevalence of sleepwalking and sleep terrors during childhood; to investigate the link between early sleep terrors and sleepwalking later in childhood; and to evaluate the degree of association betwee...

N A RECENT publication, Ebrahim and colleagues state in their abstract that they have provided an assessment of “all known scientific studies of the effects of alcohol on the nocturnal sleep of healthy volunteers” (Ebrahim et al., 2013, p. 539). Our review of this article found it to be seriously flawed by research design and statistical problems....

To explore the relationship between occurrence of drug dreams (DDs) and daytime negative affect and drug craving during the course of a 5-week treatment program for substance dependence. Using the dream journal methodology, 86 participants reported occurrence of dreams, dream content, and ratings of affect and drug craving. The relationships betwee...

The source-monitoring paradigm suggests that dreams could be an important source of naturally occurring false memories. However, the malleability of memories for dreams remains to be investigated. The purpose of this study was to evaluate the impact of suggestions on subsequent dream recall. Immediate dream recall collected in a sleep laboratory wa...

Peu d’études se sont intéressées aux cauchemars chez les enfants. Nous proposons ici une recension de ces dernières afin d’en évaluer la prévalence et les corrélats chez l’enfant, tout en répertoriant les principaux problèmes méthodologiques. Les résultats démontrent que peu importe comment ils sont définis et mesurés, les cauchemars affectent une...

Presque tous les enfants font l'expérience d'au moins une parasomnie. Heureusement, les parasomnies infantiles n'entraînent généralement pas de répercussions sérieuses et disparaissent habituellement à l'adolescence. Dans leurs formes plus intenses cependant, ces troubles peuvent perturber le sommeil de l'enfant et de sa famille, mener à des blessu...

Sleepwalking (SW) often has been associated with psychopathology, but the nature and magnitude of this relation remains unclear. The aim of our study was to investigate the presence of psychopathology in a large cohort of sleepwalkers and to determine if levels of psychopathology showed differential relations to specific characteristics of the diso...

Introduction There has been increased interest in examining sleep EEG data in terms of functional brain connectivity. These new investigative tools, however, remain practically unexplored in relation to sleep disorders. We studied the EEG coherence and interdependencies between brain areas before the onset of somnambulistic episodes recorded in the...

This study investigated the relationships between a history of childhood maltreatment, the frequency of disturbing dreams, their associated distress, and the presence of psychopathology in 352 female undergraduate volunteers. Participants completed questionnaires assessing dream recall, bad dream and nightmare frequency, nightmare distress, psychol...

Approximately 5–8 % of the general population report problems with nightmares, and a sizeable proportion of individuals exposed to a traumatic event will experience frequent nightmares. Chronic nightmares can accompany a broad range of clinical conditions but may also occur in otherwise well-functioning individuals. Targeting nightmares directly ca...

Sleepwalkers have been shown to have an unusually high number of arousals from slow wave sleep and lower slow wave activity (SWA) power during the night than controls. Because sleep deprivation increases the frequency of slow wave sleep (SWS) arousals in sleepwalkers, it may also affect the expression of the homeostatic process to a greater extent...

Sir, The recent Letter to the Editor by Drs Ebrahim and Fenwick (2012) challenges one sentence in a 2010 article published in Brain (Siclari et al. , 2010) stating that, because of the lack of reliable evidence, alcohol-induced sleepwalking should not be allowed as a defence to criminal acts. This, in turn, refers to an article published 22 years a...

Introduction: The occurence of sleepwalking episodes may be facilitated in predisposed individuals with sleep deprivation followed by daytime recovery sleep. Heart rate follows a circadian rythm with a higher activation of the autonomic nervous system (ANS) during the daytime. Our aim was to investigate ANS activation in the NREM and REM sleep of s...

It has been suggested that sleepwalkers are more difficult to awaken from sleep than are controls. However, no quantified comparisons have been made between these two populations. The main goal of this study was to assess arousal responsiveness via the presentation of auditory stimuli (AS) in sleepwalkers and controls during normal sleep and recove...

Sleepwalking (somnambulism) and sleep terrors are known as disorders of arousal and constitute two of the most frequent and impressive NREM sleep parasomnias. This chapter discusses the clinical presentation, etiology, polysomnographic findings, diagnostic considerations, prevalence, and treatment options associated with these two parasomnias. Slee...

Nightmares and other common disturbances of dreaming involve a perturbation of emotional expression during sleep. Nightmares, the most prevalent dream disturbance, are now recognized as comprising several dysphoric emotions, including especially fear, although some argue that existential (or grief) dreams should be considered a separate entity. A g...

Considerable progress has been made in the systematic study of nonrapid eye movement (NREM) sleep parasomnias. This chapter focuses on the clinical features, prevalence, pathophysiology, associated sleep parameters, and clinical variants of the prototypic NREM sleep parasomnias, namely confusional arousals, sleepwalking, and sleep terrors. Whereas...

Sleepwalking (somnambulism) and sleep terrors are known as disorders of arousal, share many characteristics, and constitute 2 of the most frequent and impressive non-rapid eye movement (NREM) sleep parasomnias. This article presents key considerations in the assessment and diagnosis of NREM arousal parasomnias. The use of sleep deprivation before p...

La prégnance de croyances significatives à l'égard du rêve à travers les différentes époques de l'humanité laisse supposer que ce phénomène revêt une certaine importance. Qu'est-ce qui est à l'origine de l'émergence de ces croyances chez certaines personnes ? Ont-elles une fonction spécifique pour l'être humain ? Les écrits portant sur ces question...

Introduction: Some pilot data suggest that cardiac activation may precede the onset of sleepwalking episodes, but findings were limited by a small sample size and methodological considerations. The present study investigated cardiac autonomic modulation in the minutes and seconds preceding sleepwalking episodes in a larger sample and with more adva...

Introduction: Some pilot data suggest that cardiac activation may precede the onset of sleepwalking episodes, but findings were limited by a small sample size and methodological considerations. The present study investigated cardiac autonomic modulation in the minutes and seconds preceding sleepwalking episodes in a larger sample and with more adva...

Introduction: Des données suggèrent qu’une activation cardiaque précède le déclenchement d’un épisode de somnambulisme, mais elles sont limitées par la méthodologie et la taille de l’échantillon. Cette étude évalue la modulation cardiaque autonome avant l’épisode dans un échantillon plus grand et avec des techniques plus avancées. Méthodologie: L’é...

STUDY OBJECTIVIES: several studies have investigated slow wave sleep EEG parameters, including slow-wave activity (SWA) in relation to somnambulism, but results have been both inconsistent and contradictory. The first goal of the present study was to conduct a quantitative analysis of sleepwalkers' sleep EEG by studying fluctuations in spectral pow...

This study examined the laboratory dream content reported by 14 patients with schizophrenia and 15 controls, with a focus on reports obtained from NonREM sleep. Both the controls' and patients' frequency of dream recall following awakenings from NonREM and REM sleep were similar to values reported for healthy participants. Patients' NonREM sleep na...

A significant proportion of individuals having been exposed to a traumatic event will experience trauma-related nightmares and approximately 5% to 8% of the general population also report problems with nightmares. Chronic nightmares may represent a primary sleep disorder rather than a symptom of a psychiatric disorder, and direct targeting of night...

Sleep disturbances and dream-related disorders play a prominent role in trauma victims' clinical profile. Although some progress has been made in understanding the impact of sleep mechanisms and nightmares in the development, maintenance, and treatment of posttraumatic stress disorder (PTSD), little is known about the actual content of trauma-relat...

Few studies have been conducted on nightmares in children. This article presents a review of the literature on the prevalence, correlates and treatment of nightmares while highlighting key methodological issues. Studies indicate that almost half of children experience nightmares and that the presence of nightmares is related to different variables...

The focus of this chapter is sleepwalking, also known as somnambulism. That people sometimes engage in complex ambulatory behaviors during sleep has been known for centuries. Shakespeare, for instance, described in Macbeth a now famous sleepwalking episode during which a guilt-ridden Lady Macbeth tries to wash imaginary blood stains from her hands...

Nightmares are a core feature of posttraumatic stress disorder (PTSD) and directly contribute to sleep disruption and poor clinical outcomes. This article first summarizes empirical findings regarding the clinical significance and characteristics of PTSD-related nightmares. Effective and promising cognitive-behavioral and pharmacological treatments...

There exists little research on dream-related beliefs and their role in peoples' lives. Our aim was to develop a questionnaire (the Inventory of Dream Experiences & Attitudes [IDEA]) to assess dream-related beliefs and inves-tigate their relations to waking-state variables. Seven hundred twenty-five participants completed the IDEA, and 357 particip...

Research indicates that recurrent dreams in adults are associated with impoverished psychological well-being. Whether similar associations exist in children remains unknown. The authors hypothesized that children reporting recurrent dreams would show poorer psychosocial adjustment than children without recurrent dreams. One hundred sixty-eight 11-y...

Many clinical, laboratory and non-laboratory studies have examined dream content reported by patients with schizophrenia but findings have been variable and inconsistent. Using both questionnaire-based measures and laboratory REM sleep awakenings, we investigated dream content in 14 patients with schizophrenia (mean age=25.5+/-3.2 years) under atyp...

Experimental attempts to induce sleepwalking with forced arousals during slow-wave sleep (SWS) have yielded mixed results in children and have not been investigated in adult patients. We hypothesized that the combination of sleep deprivation and external stimulation would increase the probability of inducing somnambulistic episodes in sleepwalkers...

Studies on nightmare frequency have yielded inconsistent results. We compared the frequency of nightmares and bad dreams obtained with retrospective methods (annual and monthly estimates) and with two types of prospective measures (narrative and checklist logs). Four hundred and eleven participants completed retrospective estimates of nightmare and...

Somnambulism affects up to 4% of adults and constitutes one of the leading causes of sleep-related violence and self-injury. Diagnosing somnambulism with objective instruments is often difficult because episodes rarely occur in the laboratory. Because sleep deprivation can precipitate sleepwalking, we aimed to determine the effects of 25 hours of s...

Many studies have reported positive correlations between dream recall frequency (DRF) and measures of absorption, psychological boundaries and attitude towards dreams. A majority of these studies, however, have relied exclusively on retrospective measures of DRF even though daily dream logs are generally considered to be more direct and valid measu...

The purpose of this review is to identify the main factors influencing dream recall frequency by focussing on the most recent developments and important contributions to the field. In summary, the capacity to produce dream experiences appears to depend on visuospatial skills while the capacity to recall dreams depends primarily on motivational fact...

proposed an intriguing and detailed evolutionary theory of dreams which stipulates that the biological function of dreaming is to simulate threatening events and to rehearse threat avoidance behaviors. The goal of the present study was to test this theory using a sample of 212 recurrent dreams that was scored using a slightly expanded version of th...

Zadra, Desjardins, and Marcotte (2006) tested several predictions derived from the Threat Simulation Theory of dreaming (Revonsuo, 2000a) in a large sample of recurrent dreams. In response to these findings, Valli and Revonsuo (2006) presented a commentary outlining alternate conceptualizations and explanations for the results obtained. We argue th...

Nightmares are usually defined as frightening dreams that awaken the sleeper. This study uses the waking criterion to distinguish between nightmares and bad dreams and investigated the variety and intensity of emotions reported in each form of disturbing dream. Ninety participants recorded their dreams for 4 consecutive weeks and, for each dream re...

Introduction : Nightmare frequency is often assessed with questionnaire items. Research based on prospective log data has shown that retrospective measures underestimate nightmare frequency. It has been suggested that this underestimation may be due to increased dream recall caused by keeping a daily log. Our first goal was to assess the accuracy o...

Hypersynchronous delta activity (HSD) is usually described as several continuous high-voltage delta waves (> or = 150 microV) in the sleep electroencephalogram of somnambulistic patients. However, studies have yielded varied and contradictory results. The goal of the present study was to evaluate HSD over different electroencephalographic derivatio...

This longitudinal study tested the continuity hypothesis, which postulates that waking states and concerns are reflected in dreams. The relationship between dream content and negative waking affect was investigated both at fixed points in time and over a 6- to 10-year period. Twenty-eight participants completed measures of psychological well-being...

Almost every published study having examined the association between people’s dream recall frequency (DRF) and their Attitude Towards Dreams has found a positive relation. However, all but two of these studies have relied exclusively on Estimated DRF as the measure of DRF. The main goal of the present study was to evaluate the hypothesis that attit...

Questionnaire studies often rely on self-report evaluations of past dream experiences to assess people's dream content. This approach, however, assumes that there exists a valid relationship between self-reported information on the content of one's everyday dreams and the dream experiences themselves. The goal of the present study was to test the i...

Exposure, abreaction, and mastery have been proposed as the therapeutic processes of nightmare (NM) reduction. Imagery rehearsal therapy (IRT) effectively reduces NMs but involves minimal exposure and abreaction. The authors investigated the use of mastery in the scripting of new dreams (NDs) elaborated during IRT. NM and ND reports were collected...

Early studies found that electroencephalographic (EEG) recordings during somnambulistic episodes were characterized by a combination of alpha, theta, and delta frequencies, without evidence of clear wakefulness. Three postarousal EEG patterns associated with slow-wave sleep (SWS) arousals were recently identified in adults with sleepwalking and sle...

To investigate the dimensional structure of dreams, the Typical Dreams Questionnaire (TDQ) was administered to 1181 first-year University students in three Canadian cities. A profile of themes was found that varied little by age, gender or region; however, differences that were identified could be interpreted as due to developmental milestones, per...

L'objectif de cet article est de présenter une brève revue de la documentation scientifique sur l'intrusion de sensations douloureuses lors du sommeil. Historiquement, il est reconnu qu'un sujet humain peut rapporter une expérience douloureuse associée à un rêve. Toutefois, l'analyse du contenu onirique révèle que la douleur est rarement présente d...

The goal of this paper is to present a review of the literature pertaining to the nature and prevalence of pain in dreams in various populations. We begin by covering historical points of view concerning the possibility of experiencing pain sensations while dreaming. This is followed by an examination of descriptive and empirical studies on the pre...