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This paper introduces a novel controlled adaptive mental causal network model addressing how dreams overnight can influence creativity in waking life. The network model depicts in a causal, dynamic, and generic manner which adaptive mental processes underlie the connection between dreams and creativity and is shown to be validated with the existing cognitive neuroscience literature. [ABSTRACT FROM AUTHOR]

Anaesthetic-induced unresponsiveness and non-rapid eye movement (NREM) sleep share common neural pathways and neurophysiological features. We hypothesised that these states bear resemblance also at the experiential level. We compared, in a within-subject design, the prevalence and content of experiences in reports obtained after anaesthetic-induced unresponsiveness and NREM sleep. Healthy males (N =39) received dexmedetomidine (n =20) or propofol (n =19) in stepwise doses to induce unresponsiveness. Those rousable were interviewed and left unstimulated, and the procedure was repeated. Finally, the anaesthetic dose was increased 50%, and the participants were interviewed after recovery. The same participants (N =37) were also later interviewed after NREM sleep awakenings. Most subjects were rousable, with no difference between anaesthetic agents (P =0.480). Lower drug plasma concentrations were associated with being rousable for both dexmedetomidine (P =0.007) and propofol (P =0.002) but not with recall of experiences in either drug group (dexmedetomidine: P =0.543; propofol: P =0.460). Of the 76 and 73 interviews performed after anaesthetic-induced unresponsiveness and NREM sleep, 69.7% and 64.4% included experiences, respectively. Recall did not differ between anaesthetic-induced unresponsiveness and NREM sleep (P =0.581), or between dexmedetomidine and propofol in any of the three awakening rounds (P >0.05). Disconnected dream-like experiences (62.3% vs 51.1%; P =0.418) and memory incorporation of the research setting (88.7% vs 78.7%; P =0.204) were equally often present in anaesthesia and sleep interviews, respectively, whereas awareness, signifying connected consciousness, was rarely reported in either state. Anaesthetic-induced unresponsiveness and NREM sleep are characterised by disconnected conscious experiences with corresponding recall frequencies and content. Clinical trial registration. This study was part of a larger study registered at ClinicalTrials.gov (NCT01889004). [ABSTRACT FROM AUTHOR]

Although spontaneous memory reactivations during sleep have long been studied in rodents, recent advances have allowed their detection and characterization in humans using intracranial electroencephalography (EEG), high-density EEG, and fMRI recordings. Both rodent and human studies are revealing that memory reactivations can be selective, fragmented, temporally transformed, and 'imaginary'. A new era of sleep and dream engineering brings novel methods designed to influence both memory consolidation and dream content, and these support growing evidence that incorporating recent memories into dreams is associated with improved performance. These developments have spurred the discussion on whether memory reactivations are the neural basis for dreaming, but evidence for this interpretation is mixed because the two phenomena show both crucial similarities and differences. Newly encoded memory traces are spontaneously reactivated during sleep. Since their discovery in the 1990s, these memory reactivations have been discussed as a potential neural basis for dream experiences. New results from animal and human research, as well as from the rapidly growing field of sleep and dream engineering, provide essential insights into this question, and reveal both strong parallels and disparities between the two phenomena. We suggest that, although memory reactivations may contribute to subjective experiences across different states of consciousness, they are not likely to be the primary neural basis of dreaming. We identify important limitations in current research paradigms and suggest novel strategies to address this question empirically. [ABSTRACT FROM AUTHOR]

Objective/background: Many studies have reported associations between disturbing dream occurrence and internalizing symptoms in adults, but the extent to which such associations also characterize adolescents remains unknown. The main goal of the present longitudinal study was to evaluate the strength and stability of the associations between disturbing dream frequency, suicidal ideation, and internalizing symptoms from ages 13 to 18.Methods: Participants (N = 434) drawn from two longitudinal birth cohort studies on child development in the province of Quebec, Canada, completed annual self-reports of disturbing dream frequency, suicidal ideation, and levels of depression and anxiety.Results: Two separate cross-lagged panel models for symptoms of depression and anxiety were conducted with both models showing similar results. In early adolescence, high levels of and higher change in disturbing dream frequency were associated with increased odds of reporting later suicidal ideation, whereas in mid to late adolescence, increased odds of reporting suicidal ideation at age 17 was associated with increased disturbing dream frequency at age 18. Across adolescence, increased levels of depression and anxiety were associated with increased odds of reporting later suicidal ideation and increased disturbing dream frequency.Conclusions: These findings support previous literature suggesting that disturbing dream frequency, depression, and anxiety, are risk factors for suicidal ideation throughout adolescence. The present longitudinal study allows for a refinement of our conceptualization of disturbing dream and their relation to suicide and internalizing symptoms throughout adolescence and suggests that the collection of information on disturbing dream and internalizing symptoms during early adolescence may help screen adolescents for suicide risk. [ABSTRACT FROM AUTHOR]

Symptoms of insomnia and frequent nightmares are prevalent in psychotic disorders, and are associated with psychotic-like experiences (PLEs) in the non-clinical population. Whereas the role of impaired sleep in psychosis was extensively examined by longitudinal and interventional approaches, studies on the association between psychosis and dream quality are scarce, and mainly cross-sectional. We conducted a three-week long prospective study in a group of healthy adults (N = 55), assessed schizotypal traits, daily PLEs, and the emotional quality of dreams recalled in the morning (N = 490). We extracted the latent factors of schizotypal traits and dream emotions, and examined the predictive value of trait-and state-like variables on day-to-day reports of PLEs and dream quality. PLEs reported in the evening predicted emotionally more negative and salient dream reports the following morning. On the other hand, the quality of dreams were not predictive of PLEs reported later during the day. Schizotypal personality traits were differentially associated with dream quality: Introvertive Anhedonia, Cognitive Disorganization, and General-Disorganized schizotypy were linked to more negative dream valence, whereas Unusual Experiences were associated with more salient dreams. Our findings highlight the relevance of the multidimensional nature of schizotypal traits, the role of different facets of schizotypy in daytime and nocturnal mental experiences, and the day-to-day associations between PLEs and dream affect. GENERAL SCIENTIFIC SUMMARIES (GSS): The aim of the study was to examine the temporal associations between psychotic-like experiences and dream emotions, taking into account the trait factors of schizotypy. Psychotic-like experiences during the evening hours predicted reporting more negative and salient dreams the following morning, and schizotypal personality traits were differentially associated with the dimensions of dream emotions. [ABSTRACT FROM AUTHOR]

Changes in sleep and dreams are often observed during pregnancy. Dreaming may represent privileged access to the inner world of individuals, providing relevant information about their well-being. For this reason, a growing but heterogeneous literature has investigated dream experiences of pregnant women. The present paper aimed to systematically review the available evidence on the relationship between pregnancy and oneric activity, focusing on dream and nightmare frequency, dream contents, and emotional features. Moreover, dream changes between pre-partum and post-partum periods and the impact of previous pregnancy-related adverse events on dreaming have been summarized. Overall, 17 studies have been examined. The reviewed evidence suggests that women tend to have an abundant production of dreams and nightmares during pregnancy, and some results support the view that a high rate of dream recall is associated with poor sleep quality. Most studies have shown a high presence of pregnancy-related dream content, likely reflecting waking experiences and concerns. Additionally, dreaming may promote psychological preparation and activation of functional coping strategies to face life changes after childbirth. • Dreams may represent privileged access to the inner world of pregnant women. • Dreaming could promote emotional regulation in pregnant women. • Literature on dreaming in pregnancy is still characterized by many methodological flaws. • The assessment of dreams may be useful for health professionals to evaluate mood-related aspects of pregnancy. [ABSTRACT FROM AUTHOR]

Insomnia and nightmares are both prevalent and debilitating sleep difficulties. The present systematic review aims to document the relationships between insomnia and nightmares in individuals without a concomitant psychopathology. The relationships between insomnia and dreams are also addressed. PsycINFO and Medline were searched for papers published in English or French from 1970 to March 2023. Sixty-seven articles were included for review. Most results support positive relationships between insomnia variables and nightmare variables in individuals with insomnia, individuals with nightmares, the general population, students, children and older adults, and military personnel and veterans. These positive relationships were also apparent in the context of the COVID-19 pandemic. Some psychological interventions, such as Imagery Rehearsal Therapy, might be effective in alleviating both nightmares and insomnia symptoms. Regarding the relationships between insomnia and dreams, compared with controls, the dreams of individuals with insomnia are characterized by more negative contents and affects. The results show that insomnia and nightmares are connected and may be mutually aggravating. A model is proposed to explain how insomnia might increase the likelihood of experiencing nightmares, and how nightmares can in turn lead to sleep loss and nonrestorative sleep. [ABSTRACT FROM AUTHOR]

Sedated patients have graded levels of consciousness and perceptual connection with the outside world. Disconnection is associated with widespread changes in the electroencephalogram, whereas full unconsciousness is linked with decreased activity specifically in the deep midline regions of the brain. These findings can be interpreted within the predictive coding model of consciousness as differences in model generation vs discrepancy detection. Anaesthetists should be cognisant that apparently unresponsive patients might still have some ongoing partially disconnected consciousness activity. [ABSTRACT FROM AUTHOR]

Objectives: Nightmares are extremely unpleasant and vivid recurring dreams that are accompanied with awakening during sleep. However, earlier studies were mostly conducted with children and adults, with very few studies on nightmares in older adults. This population-based study aims to investigate the prevalence of nightmares and its associated factors nightmares in the elderly.Methods: This study utilized a subsample from the Korean Genome and Epidemiology Study (KoGES). Participants (n = 2940; mean age 63.71 ± 6.73) completed the questionnaires on nightmares (Disturbing Dream and Nightmare Severity Index; DDNSI), depression, suicidal ideation, sleep quality and stress.Results: Among the sample, 2.7% (n = 79) were classified into the nightmare group (NG), which was classified with DDNSI scores. In the age group over 70, prevalence of nightmares was 6.3% (n = 37), which was significantly higher than other age groups. Marital status, employment status and family income were associated with nightmares. Additionally, NG reported significantly more sleep problems, higher suicidal ideation, depression and stress compared to the non-nightmare group (N-NG). Logistic regression analyses results indicated that the NG was 4.35 times at higher risk for depression, and 3.16 higher risks for stress, and 3.45 higher risks for suicidal ideation compared to the N-NG after controlling for covariates.Conclusions: Our results indicate that psychological and demographic factors are associated with nightmares in the elderly. Furthermore, this population-based cohort study showed the prevalence of nightmares increased after age 70, which suggests the need for further studies of nightmares in older populations. [ABSTRACT FROM AUTHOR]

• A cellular mechanism of dream generation is proposed. • ACh facilitates this state of processing, which we call apical drive. • Apical drive can explain properties of dreams. • Apical drive may also contribute to waking experiences, such as mental imagery. Dreams are internally generated experiences that occur independently of current sensory input. Here we argue, based on cortical anatomy and function, that dream experiences are tightly related to the workings of a specific part of cortical pyramidal neurons, the apical integration zone (AIZ). The AIZ receives and processes contextual information from diverse sources and could constitute a major switch point for transitioning from externally to internally generated experiences such as dreams. We propose that during dreams the output of certain pyramidal neurons is mainly driven by input into the AIZ. We call this mode of functioning "apical drive". Our hypothesis is based on the evidence that the cholinergic and adrenergic arousal systems, which show different dynamics between waking, slow wave sleep, and rapid eye movement sleep, have specific effects on the AIZ. We suggest that apical drive may also contribute to waking experiences, such as mental imagery. Future studies, investigating the different modes of apical function and their regulation during sleep and wakefulness are likely to be richly rewarded. [ABSTRACT FROM AUTHOR]

Experimental research has shown that poor sleep triggers psychotic experiences, even in healthy participants. This warrants an in-depth investigation of this mechanism in a naturalistic environment, an exploration of which particular aspects of poor sleep trigger psychotic symptoms, and a test for reverse effects of symptoms on sleep. For this purpose, we conducted a 14-day ambulatory assessment study with 82 young adults (age: M = 21.24 years, SD = 1.54; 64.6% female), half of which were characterized by elevated psychosis proneness. Objective sleep parameters (actigraphically-measured sleep time, wake after sleep onset, sleep efficiency), self-reported sleep parameters (feeling rested, dream recall, dream valence), and psychotic symptoms (paranoid symptoms, hallucinatory experiences) were assessed once per day. Using multilevel regressions (928 data points), we found that shorter sleep time and negative dream valence predicted paranoid symptoms, whereas feeling less rested and dream recall predicted hallucinatory experiences. In participants with elevated psychosis proneness, associations with the aforementioned sleep parameters were increased for hallucinatory experiences but not for paranoid symptoms. Finally, we found bidirectional associations between poor sleep and paranoid symptoms but only unidirectional associations between poor sleep and hallucinatory experiences. The findings corroborate the relevance of sleep disturbance as a predictor of psychotic experiences. Future studies should further investigate the potential of sleep interventions to prevent psychotic symptoms and disorders. [ABSTRACT FROM AUTHOR]

Objective: Odor presentation is a crucial tool in the experimental investigation of dreaming since odors rarely cause arousal, and are processed in the brain during sleep. Our previous study demonstrated that the presentation of a preferred odor during rapid eye movement (REM) sleep-induced negative dream emotions. However, preference and familiarity of an odor are known to be strongly related to each other in olfactory perception. Consequently, the above result might have been due to the confounding effects of familiarity. Therefore, the present study was designed to clarify the effects of an individual's degree of familiarity with an odor on negative emotions experienced when dreaming.Methods: The airflow with phenylethyl alcohol (PEA: rose-like smell) was presented as a stimulus of experimental condition, and odorless airflow was presented as the control. Participants who were familiar (n = 7) and unfamiliar (n = 7) with the odor of PEA experienced both conditions during REM sleep in the second and later sleep cycle. Then, they were awakened, and they rated the characteristics of their dream using a questionnaire.Results and Conclusions: Participants who were familiar with the odor of PEA rated their dreams more negatively in the experimental condition relative to the control condition. It is concluded based on these results that a familiar odor may induce negative emotion in dreams, possibly because familiar odors tend to be perceived more strongly, and the olfactory pathway has direct connections to the amygdala, which is primarily involved in processing negative emotions. [ABSTRACT FROM AUTHOR]

One can be aware of the effort needed to memorize a new fact or to recall the name of a new acquaintance. Because of experiences like this, learning can seem to have only two components, encoding information and, after some delay, retrieving information. To the contrary, learning entails additional, intervening steps that sometimes are hidden from the learner. For firmly acquiring fact and event knowledge in particular, learners are generally not cognizant of the necessity of offline consolidation. The memories that persist to be available reliably at a later time, according to the present conceptualization, are the ones we repeatedly rehearse and integrate with other knowledge, whether we do this intentionally or unknowingly, awake or asleep. This article examines the notion that learning is not a function of waking brain activity alone. What happens in the brain while we sleep also impacts memory storage, and consequently is a critical component of learning. The idea that memories can change over time and become enduring has long been present in memory research and is foundational for the concept of memory consolidation. Nevertheless, the notion that memory consolidation happens during sleep faced much resistance before eventually being firmly established. Research is still needed to elucidate the operation and repercussions of repeated reactivation during sleep. Comprehensively understanding how offline memory reactivation contributes to learning is vital for both theoretical and practical considerations. • Recurring memory reactivation drives consolidation, producing enduring memories. • Reactivation need not be intentional; it occurs offline during wake and during sleep. • Memory storage can be probed during sleep using Targeted Memory Reactivation (TMR). • TMR combined with measuring sleep physiology shows how memory storage evolves. • Offline memory reactivation is a valuable component of sleep and learning. [ABSTRACT FROM AUTHOR]

Sleep is typically considered a state of disconnection from the environment, yet instances of external sensory stimuli influencing dreams have been reported for centuries. Explaining this phenomenon could provide valuable insight into dreams' generative and functional mechanisms, the factors that promote sleep continuity, and the processes that underlie conscious awareness. Moreover, harnessing sensory stimuli for dream engineering could benefit individuals suffering from dream-related alterations. This PRISMA-compliant systematic review assessed the current evidence concerning the influence of sensory stimulation on sleep mentation. We included 51 publications, of which 21 focused on auditory stimulation, ten on somatosensory stimulation, eight on olfactory stimulation, four on visual stimulation, two on vestibular stimulation, and one on multimodal stimulation. Furthermore, nine references explored conditioned associative stimulation: six focused on targeted memory reactivation protocols and three on targeted lucid reactivation protocols. The reported frequency of stimulus-dependent dream changes across studies ranged from 0 to ∼80%, likely reflecting a considerable heterogeneity of definitions and methodological approaches. Our findings highlight a lack of comprehensive understanding of the mechanisms, functions, and neurophysiological correlates of stimulus-dependent dream changes. We suggest that a paradigm shift is required for meaningful progress in this field. [ABSTRACT FROM AUTHOR]

Semantic representations in higher sensory cortices form the basis for robust, yet flexible behavior. These representations are acquired over the course of development in an unsupervised fashion and continuously maintained over an organism's lifespan. Predictive processing theories propose that these representations emerge from predicting or reconstructing sensory inputs. However, brains are known to generate virtual experiences, such as during imagination and dreaming, that go beyond previously experienced inputs. Here, we suggest that virtual experiences may be just as relevant as actual sensory inputs in shaping cortical representations. In particular, we discuss two complementary learning principles that organize representations through the generation of virtual experiences. First, "adversarial dreaming" proposes that creative dreams support a cortical implementation of adversarial learning in which feedback and feedforward pathways engage in a productive game of trying to fool each other. Second, "contrastive dreaming" proposes that the invariance of neuronal representations to irrelevant factors of variation is acquired by trying to map similar virtual experiences together via a contrastive learning process. These principles are compatible with known cortical structure and dynamics and the phenomenology of sleep thus providing promising directions to explain cortical learning beyond the classical predictive processing paradigm. [ABSTRACT FROM AUTHOR]

Ordinary human experience is embedded in a web of causal relations that link the brain to the body and the wider environment. However, there might be conditions in which brain activity supports consciousness even when that activity is fully causally isolated from the body and its environment. Such cases would involve what we call islands of awareness: conscious states that are neither shaped by sensory input nor able to be expressed by motor output. This Opinion paper considers conditions in which such islands might occur, including ex cranio brains, hemispherotomy, and in cerebral organoids. We examine possible methods for detecting islands of awareness, and consider their implications for ethics and for the nature of consciousness. Awareness may persist in fully disconnected cortical islands. We identify both natural and artificial examples of potential islands of awareness. Detecting islands of awareness poses difficult but often addressable challenges. The possibility of islands of awareness raises important ethical and legal issues. The discovery of islands of awareness would have important implications for debates about the nature of consciousness. [ABSTRACT FROM AUTHOR]

Highlights • EEG studies of lucid dreaming are mostly underpowered and show mixed results. • Preliminary neuroimaging data implicates frontoparietal cortices in lucid dreaming. • Cholinergic stimulation with mental set shows promise for inducing lucid dreams. • We present best-practice procedures to investigate lucid dreaming in the laboratory. Abstract Lucid dreaming refers to the phenomenon of becoming aware of the fact that one is dreaming during ongoing sleep. Despite having been physiologically validated for decades, the neurobiology of lucid dreaming is still incompletely characterized. Here we review the neuroscientific literature on lucid dreaming, including electroencephalographic, neuroimaging, brain lesion, pharmacological and brain stimulation studies. Electroencephalographic studies of lucid dreaming are mostly underpowered and show mixed results. Neuroimaging data is scant but preliminary results suggest that prefrontal and parietal regions are involved in lucid dreaming. A focus of research is also to develop methods to induce lucid dreams. Combining training in mental set with cholinergic stimulation has shown promising results, while it remains unclear whether electrical brain stimulation could be used to induce lucid dreams. Finally, we discuss strategies to measure lucid dreaming, including best-practice procedures for the sleep laboratory. Lucid dreaming has clinical and scientific applications, and shows emerging potential as a methodology in the cognitive neuroscience of consciousness. Further research with larger sample sizes and refined methodology is needed. [ABSTRACT FROM AUTHOR]

Wakefulness, non-rapid eye-movement (NREM) and rapid eye-movement (REM) sleep differ from each other along three dimensions: behavioral, phenomenological, physiological. Although these dimensions often fluctuate in step, they can also dissociate. The current paradigm that views sleep as made of global NREM and REM states fail to account for these dissociations. This conundrum can be dissolved by stressing the existence and significance of the local regulation of sleep. We will review the evidence in animals and humans, healthy and pathological brains, showing different forms of local sleep and the consequences on behavior, cognition, and subjective experience. Altogether, we argue that the notion of local sleep provides a unified account for a host of phenomena: dreaming in REM and NREM sleep, NREM and REM parasomnias, intrasleep responsiveness, inattention and mind wandering in wakefulness. Yet, the physiological origins of local sleep or its putative functions remain unclear. Exploring further local sleep could provide a unique and novel perspective on how and why we sleep. • Wake-like and sleep-like activity can be observed concomitantly in different brain regions. • Within sleep, local modulations of sleep depth can account for parasomnias, intra-sleep responsiveness or dreaming. • Within wake, sleep-like activity increases in a time and use-dependent fashion and is associated with attentional lapses. • Local sleep could be initiated by molecules regulating cerebral vasodilation, neuroinflammation, and neural plasticity. [ABSTRACT FROM AUTHOR]

Nightmares are a common sleep disorder, defined as highly disturbing mentation which usually awakens the individual from rapid eye movement (REM) sleep. While nightmares are mainly a REM sleep phenomenon, Picard-Deland et al., (2017) recently showed an association between nightmare recall and sleep spindles, which are a non-rapid eye movement (NREM) oscillatory feature. Their results pointed to fewer slow spindles and a higher oscillatory frequency for fast spindles among frequent nightmare recallers compared with controls. To test the suggestion that nightmares stem from changes to emotional neural circuits arising in early childhood (Nielsen, 2017), including early changes in sleep spindles (Scholle et al., 2007), we investigated if the spindle features of early-onset nightmare recallers (ie, recalling nightmares since childhood) (N = 22), differed from those of late-onset nightmare recallers (ie, since adolescence or adulthood) (N = 11), or from those of controls (N = 23). A retrospective analysis of the sleep spindles of 56 participants who had undergone a polysomnographically-recorded morning nap revealed that Early starters uniquely exhibited lower slow spindle densities in five of six derivations (all p < 0.045) and higher fast spindle frequencies in all six derivations (all p < 0.015). These results add precision to previously reported findings for Nightmare recallers: spindle differences are shown to hold only for Early starters. The lifelong occurrence of nightmares may be closely tied to disruptions in the normal development of spindle generation processes occurring early in development. [ABSTRACT FROM AUTHOR]

Idiopathic nightmares are a common disturbance of rapid eye movement sleep (REM) sleep, but studies of comorbid pathologies and sleep architecture suggest that non-REM (NREM) sleep is also affected. Sleep spindles are a NREM sleep characteristic associated with both pathophysiology and sleep-dependent memory consolidation, yet they have not been evaluated in frequent nightmare recallers. The morning naps of 38 participants with frequent idiopathic nightmares (mean age: 23.7 ± 3.78 years) and 25 age- and sex-matched controls (23.9 ± 3.65 years) were recorded and their sleep evaluated. A custom spindle detector assessed NREM sleep stage 2 (N2) sleep spindles on six electroencephalogram (EEG) derivations (F3, F4, C3, C4, O1, and O2) for density (number spindles/N2 time), mean frequency, and amplitude. Total spindles (10-16 Hertz (Hz) range), slow spindles (10-12.79 Hz), and fast spindles (12.8-16 Hz) were all assessed separately. Compared with the Control group, the Nightmare group had longer N2 sleep latency and a marginally greater %N2 sleep. The Nightmare group also had a lower than normal density of slow spindles in most EEG derivations, a higher density of fast spindles in frontal derivations, and an elevated fast spindle oscillatory frequency-"faster fast" spindles-mainly in central derivations. These differences withstood controls for pre-existing group differences in depression. Correlational analyses demonstrated a further pattern of group differences by which higher pathology scores were associated with higher slow spindle densities and slower spindle frequencies for the Nightmare but not the Control group. A similar pattern was observed for some dream content measures, ie, the Nightmare group showed positive correlations of slow spindle density with dreamed fear and word count and negative correlations with dreamed positive emotion. Conversely, the Control group showed opposite trends. Results thus demonstrate abnormalities in the composition of N2 sleep-and especially in N2 spindles-among frequent nightmare recallers and link these abnormalities to both trait (psychopathology) and state (dream content) factors. Spindle findings for psychopathology resemble, but are not identical with, previous findings for patients with major depression, social anxiety, and schizophrenia and are thus consistent with an explanation implicating spindles as trait markers of psychopathology. Correlational analyses go beyond a trait explanation to suggest several possible state-based explanations involving memory consolidation mechanisms, specifically, the possibility that spindles index either emotional or verbal task-based processes. [ABSTRACT FROM AUTHOR]

In the late 50s Michel Jouvet discovered the presence of muscle atonia during REM sleep in cats and created the first model of REM sleep behavior disorder. He built and led in Lyon, France, the "Laboratory of Molecular Dream Science" (a merry oxymoron to silently protest against the research policy of favoring molecular biology over physiology), where in the late 80s, you could cross people who had worked on sleep in the python, tench fish, tortoise, iguana, hen, lamb, mouse, rat and cat. This brilliant physiologist was also a great storyteller with a very good sense of humor. He supported the theory that dreaming is equivalent to REM sleep (which he called "paradoxical sleep"), kept his own dream diary, and imagined that the ponto-geniculo-occipital waves during REM sleep could compose the song sheet of dreams. He wrote several books published in French on dreams and dreaming. [ABSTRACT FROM AUTHOR]

A tendency for experiencing unusual dream and sleep-wake transition phenomena (e.g., recurrent dreams, hypnagogic hallucinations, and confusion upon awakening), labeled general sleep experiences (GSEs), is linked with stress as well as psychological distress, explicit as well as covert. We hypothesized that alexithymia may moderate the relationship between stress and GSEs. Undergraduate students ( N = 187) completed online questionnaires; Three months later, n = 78 of them reported perceived stress and dreaming each day for 14 days. Regression analyses for trait data and multilevel modeling for daily diary data both revealed a pattern of two competing alexithymic mechanisms: difficulty in identifying feelings was related to increased GSEs, whereas externally-oriented thinking was related to decreased GSEs. As hypothesized, a cross-level interaction was found: daily stress predicted daily GSEs of the following night, only among those who reported difficulty identifying their emotions. It seems that those who experience GSEs following stress, tend to be internally-oriented (i.e., notice their inner experiences), yet find it difficult to understand and identify those experiences. GSEs seem to represent a nocturnal manifestation of unprocessed emotion. [ABSTRACT FROM AUTHOR]

Recent advances in electrophysiological [e.g., surface high-density electroencephalographic (hd-EEG) and intracranial recordings], video-polysomnography (video-PSG), transcranial stimulation and neuroimaging techniques allow more in-depth and more accurate investigation of the neural correlates of dreaming in healthy individuals and in patients with brain-damage, neurodegenerative diseases, sleep disorders or parasomnias. Convergent evidence provided by studies using these techniques in healthy subjects has led to a reformulation of several unresolved issues of dream generation and recall [such as the inter- and intra-individual differences in dream recall and the predictivity of specific EEG rhythms, such as theta in rapid eye movement (REM) sleep, for dream recall] within more comprehensive models of human consciousness and its variations across sleep/wake states than the traditional models, which were largely based on the neurophysiology of REM sleep in animals. These studies are casting new light on the neural bases (in particular, the activity of dorsal medial prefrontal cortex regions and hippocampus and amygdala areas) of the inter- and intra-individual differences in dream recall, the temporal location of specific contents or properties (e.g., lucidity) of dream experience and the processing of memories accessed during sleep and incorporated into dream content. Hd-EEG techniques, used on their own or in combination with neuroimaging, appear able to provide further important insights into how the brain generates not only dreaming during sleep but also some dreamlike experiences in waking. [ABSTRACT FROM AUTHOR]

Dreams are often viewed as fascinating but irrelevant mental epihenomena of the sleeping mind with questionable functional relevance. Despite long hours of oneiric activity, and high individual differences in dream recall, dreams are lost into oblivion. Here, we conceptualize dreaming and dream amnesia as inherent aspects of the reactive and predictive homeostatic functions of sleep. Mental activity during sleep conforms to the interplay of restorative processes and future anticipation, and particularly during the second half of the night, it unfolds as a special form of non-constrained, self-referent, and future-oriented cognitive process. Awakening facilitates constrained, goal-directed prospection that competes for shared neural resources with dream production and dream recall, and contributes to dream amnesia. We present the neurophysiological aspects of reactive and predictive homeostasis during sleep, highlighting the putative role of cortisol in predictive homeostasis and forgetting dreams. The theoretical and methodological aspects of our proposal are discussed in relation to the study of dreaming, dream recall, and sleep-related cognitive processes. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Unusual sleep and dream experiences—such as elevated dream recall, nightmares, hypnagogic hallucinations, flying dreams, or waking dreams—constitute a trait of atypical nocturnal cognitions that has been associated with life stress and psychopathological distress, as well as terrorism-related stress. In the present study, this trait was explored as a predictor of psychopathological distress following Israel's 2012 “Operation Pillar of Defense” by employing a prospective-longitudinal design. Fifty-three participants, for whom baseline data on psychopathology, sleep, and dreaming were previously assessed, were contacted again in the week following the conclusion of the Operation. They filled out questionnaires regarding sleep experiences, psychopathological distress, the degree of exposure to terrorism, dissociative experiences, and sleep quality. An elevation in psychopathological symptoms, from pre- to post-Operation measurements, was predicted by degree of exposure to terrorism, but also by pre-Operation sleep experiences. This effect of unusual dreaming in prospectively predicting psychopathological reactions to terrorism-related stress was also replicated when reanalyzing existing longitudinal data from a previous study on exposure to terrorism. These novel findings point to the importance of individual differences in nocturnal cognition as clinical indicators of risk for stress reactivity and psychopathology in the face of traumatic stress. [ABSTRACT FROM AUTHOR]

Summary The idea that dreaming can serve as a model for psychosis has a long and honourable tradition, however it is notoriously speculative. Here we demonstrate that recent research on the phenomenon of lucid dreaming sheds new light on the debate. Lucid dreaming is a rare state of sleep in which the dreamer gains insight into his state of mind during dreaming. Recent electroencephalogram (EEG) and functional magnetic resonance imaging (fMRI) data for the first time allow very specific hypotheses about the dream–psychosis relationship: if dreaming is a reasonable model for psychosis, then insight into the dreaming state and insight into the psychotic state should share similar neural correlates. This indeed seems to be the case: cortical areas activated during lucid dreaming show striking overlap with brain regions that are impaired in psychotic patients who lack insight into their pathological state. This parallel allows for new therapeutic approaches and ways to test antipsychotic medication. [ABSTRACT FROM AUTHOR]

Highlights: [•] Dream content analysis in 11 congenitally blind (CB), 14 late blind (LB) and 25 sighted controls (SC). [•] CB and LB subjects have fewer visual dream impressions than SC. [•] Blindness duration correlates negatively with duration of visual dream impressions in LB. [•] CB report more auditory, tactile, gustatory and olfactory dream components compared to SC. [•] CB subjects report more nightmares compared to LB and SC. [ABSTRACT FROM AUTHOR]

Abstract: Cognitive bizarreness has been shown to be equally elevated in the dream and waking mentation of acutely symptomatic inpatients diagnosed with affective and non-affective psychoses. Although some studies have reported on dream content in non-psychotic depression, no study has previously measured this formal aspect of cognition in patients hospitalized for Psychotic Major Depression (PMD). Sixty-five dreams and 154 waking fantasy reports were collected from 11 PMD inpatients and 11 age- and sex-matched healthy controls. All narrative reports were scored by judges blind to diagnosis in terms of formal aspects of cognition (Bizarreness). Dream content was also scored (Hall/Van de Castle scoring system). Unlike controls, PMD patients had similar levels of cognitive bizarreness in their dream and waking mentation. Dreams of PMD patients also differed from those of controls in terms of content variables. In particular, Happiness, Apprehension and Dynamism were found to differ between the two groups. Whereas dream content reflects a sharp discontinuity with the depressive state, cognitive bizarreness adequately measures the stability of cognition across dreams and wakefulness in PMD inpatients. [Copyright &y& Elsevier]

Searching for inspiration, or travel ideas, is part of the dreaming phase, positioned at the start of the travel process. Yet the ontological and epistemological understanding of inspiration in travel is still in infancy. Based on the inspiration literature in psychology and marketing, this study conceptualizes travel inspiration as a motivational state that drives a prospective tourist to bring newly obtained travel ideas into realization. By explaining the two distinct states, inspired-by and inspired-to, this note further proposes that inspiration can provide a potential shortcut in tourist decision making. The destination choice scenario is used to illustrate the shortcut. Travel inspiration can help researchers explore the neglected dreaming phase and irrational aspects of tourists' decision making. Tourism marketers can inspire prospective tourists by serendipitously suggesting lesser-known attractions and novel experiences, thereby allowing for a seamless experience from inspiration to booking. [ABSTRACT FROM AUTHOR]

Abstract: Sleep disturbances are common in many neurodegenerative diseases and may include altered sleep duration, fragmented sleep, nocturia, excessive daytime sleepiness, and vivid dreaming experiences, with occasional parasomnias. Although representing the “gold standard,” polysomnography is not always cost-effective or available for measuring sleep disturbance, particularly for screening. Although numerous sleep-related questionnaires exist, many focus on a specific sleep disturbance (e.g., restless legs, REM Behavior Disorder) and do not capture efficiently the variety of sleep issues experienced by such patients. We administered the 12-item Neurodegenerative Disease Sleep Questionnaire (NDSQ) and the Epworth Sleepiness Scale to 145 idiopathic Parkinson's disease patients. Principal component analysis using eigenvalues greater than 1 suggested five separate components: sleep quality (e.g., sleep fragmentation), nocturia, vivid dreams/nightmares, restless legs symptoms, and sleep-disordered breathing. These results demonstrate construct validity of our sleep questionnaire and suggest that the NDSQ may be a useful screening tool for sleep disturbances in at least some types of neurodegenerative disorders. [Copyright &y& Elsevier]

Abstract: Dreaming occurs during non-rapid eye movement (NREM) and rapid eye movement (REM) sleep, which both are regulated by homeostatic, ultradian, and circadian processes. However, the magnitude of how ultradian REM and NREM sleep and its EEG correlates impact onto dream recall remains fairly unknown. In this review, we address three questions: 1. Is there an ultradian NREM–REM sleep modulation in successful dream recall, which is gated by the circadian clock? 2. What are the key electrophysiological correlates that account for dream recall during NREM and REM sleep and 3. Are there age-related changes in the ultradian and circadian regulation in dream recall and its electrophysiological correlates? Knowledge on the specific frequency and topography NREM and REM sleep differences prior to dream recall may pinpoint to the cerebral correlates that account for this cognitive process, and hint to their possible physiological meaning. [Copyright &y& Elsevier]

Abstract: 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. [Copyright &y& Elsevier]

Abstract: Sleeping, dreaming, and health or well-being are all closely related phenomena from an experiential and cultural point of view, and yet all three are often studied in isolation from one another. In this paper, I use an ethnographic and clinical lens to compare and contrast patterns of sleeping and dreaming and their relationship to health in a rural Indonesian society and among urban middle class people in the US. I demonstrate how culturally shaped patterns of sleeping and dreaming become linked through social practice and the implication of these practices for health and well being. I underscore, in particular, the seamless connection between waking and non-waking life, how daytime activities affect patterns of sleeping and dreaming, but also how the emotional and behavioral residues of the night affect daytime life and experience. Data for the Indonesia case were collected during extended fieldwork in 1981–1983, while the U.S. data come from my ongoing part-time private practice of psychotherapy and psychoanalysis. [Copyright &y& Elsevier]

Abstract: Previous research has demonstrated disturbances in sleep continuity in subjects with borderline personality disorders (BPD). Moreover, depression-like sleep abnormalities like reduced REM latency have been found in BPD subjects, even without comorbid major depression disorder. Yet it is still unknown what the effect is of co-morbid posttraumatic stress disorder on sleep continuity and dream content in BPD patients group. The present study compared 27 unmedicated female BPD subjects and healthy controls. The patients exhibited increased sleep fragmentation, increased REM density, and reduced REM latency. The findings were independent from co-morbid posttraumatic stress response (PTSD), which was present in 33% of the patient sample. Negatively toned dreams obtained by REM awakenings and nightmares were also reported more often by the patients—also irrespective of co-morbid PTSD—whereas dreams of specific BPD behavior, like self-mutilation, were rare. Taking these finding into account, one might productively investigate whether the sleep abnormalities improve during successful treatment of BPD and whether efficient methods for treating nightmares can be beneficial for this patient group. [Copyright &y& Elsevier]

Abstract: The mesolimbic dopaminergic system (ML-DA) allows adapted interactions with the environment and is therefore of critical significance for the individual''s survival. The ML-DA system is implicated in reward and emotional functions, and it is perturbed in schizophrenia, addiction, and depression. The ML-DA reward system is not only recruited during wakeful behaviors, it is also active during sleep. Here, we introduce the Reward Activation Model (RAM) for sleep and dreaming, according to which activation of the ML-DA reward system during sleep contributes to memory processes, to the regulation of rapid-eye movement (REM) sleep, and to the generation and motivational content of dreams. In particular, the engagement of ML-DA and associated limbic structures prioritizes information with high emotional or motivational relevance for (re)processing during sleep and dreaming. The RAM provides testable predictions and has clinical implications for our understanding of the pathogenesis of major depression and addiction. [Copyright &y& Elsevier]

Abstract: Objectives: Dreams are commonly described as violent, threatening, and aggressive in patients with REM behavior disorder (RBD), but very few studies have directly investigated dream content in this population. We systematically assessed dreams in subjects with a confirmed diagnosis of idiopathic RBD (iRBD) and explored psychological traits within the group with specific focus on aggressiveness. Methods: A total of 129 dream reports was collected, of which 77 belonged to 12 iRBD patients and 52 belonged to 12 control subjects. Transcripts were analyzed with measures of both form and content. The Thematic Apperception Test was used to assess patients’ personality traits and to yield information on formal aspects of waking thought processes. Results: No statistically significant differences were found between the dreams of iRBD patients and those of normal controls in any of the applied measures. In wakefulness, passivity was found to differ between the two populations and was being higher in the iRBD group (F 9,14 =4.84, p <0.05). Conclusions: Our results do not support the anecdotal view that dreams of RBD patients contain more aggressive elements than those of the general population. However, over 80% of the patients were on treatment at the time of data collection. The “mild” waking temperament could be interpreted as an early subtle sign of the apathy that is commonly described in the context of neurodegenerative disorders. [Copyright &y& Elsevier]

Abstract: Several overlapping features have frequently been described between psychosis and the subjective experience of dreaming from the neurobiological to the phenomenological level, but whether this similarity reflects the cognitive organization of schizophrenic thought or rather that of psychotic mentation independent of diagnostic categories is still unclear. In this study, 40 actively psychotic inpatients were equally divided in two age- and education-matched groups according to their diagnosis (Schizophrenia and Bipolar Disorder). Participants were asked to report their dreams upon awakening and the Thematic Apperception Test (TAT) was administered to elicit waking fantasies; the same procedure was used in a control group of 20 non-psychiatric subjects. Two highly trained judges scored the collected material according to a Dream Bizarreness scale. The same level of cognitive bizarreness was found in TAT and dream reports of schizophrenic and manic subjects but was almost completely absent in the TAT stories of the control group. Two-way analysis of variance for repeated measures assessed the effect of diagnosis and experimental conditions (TAT stories and dream reports) on bizarreness yielding a significant interaction. Cognitive bizarreness seems to be a shared feature of dreaming and psychotic mentation, beyond diagnostic categorizations. Although these findings must be considered preliminary, this experimental measure of the cognitive architecture of thought processes seems to support the view that dreaming could be a useful model for the psychoses. [Copyright &y& Elsevier]

Abstract: The study investigated the effect of one night of sleep deprivation on dream recall at morning awakening after recovery sleep. Forty healthy subjects were studied after adaptation (A) and baseline nights (B), and a recovery (R) night following 40h of prolonged wakefulness. Parallel to the well-known recovery sleep changes (slow-wave sleep – SWS – rebound, decreased number of awakenings and of REM sleep amount), an almost complete abolition of dream recall was found, with an around 75% decrease with respect to the adaptation and baseline nights. The number of dreams recalled by those subjects with successful recall (REC) did not significantly differ between nights. Moreover, gender and sleep stage at awakening did not affect either the proportion of REC subjects or the number of dreams recalled by REC subjects during each night. Finally, the drastic impairment of dream recall after R night was associated to a larger increase of SWS and a shorter REM sleep duration. We suggest that dream recall could have been impaired during R night because: (i) the lower number of spontaneous awakenings over the night reduced the contents available in memory as possible cues for the retrieval of dream experiences at morning; (ii) mental experiences, having been elaborated during SWS more than in the other nights, were less dreamlike (i.e., perceptually vivid and bizarre) and, thus less accessible at morning recall than those elaborated during the nights with a higher proportion of REM sleep; (iii) dream contents, as a peculiar type of episodic information, were less consolidated because of the lower effectiveness of declarative memory during recovery sleep. [Copyright &y& Elsevier]

Abstract: 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 atypical antipsychotic medication and 15 healthy controls (mean age=22.3±4.2 years). The relationship between eye movement density during REM sleep and dream content was also explored. Questionnaire data revealed that when compared to controls, patients with schizophrenia report experiencing a greater number of nightmares but no significant differences were found on other measures including overall dream recall, presence of recurrent dreams, and frequency of specific emotions. 39 dream reports were collected from each group following awakenings from REM sleep. Laboratory dream narratives from the patients were shorter and, after controlling for report length, most significant differences in dream content between the two groups disappeared with the exception of a greater proportion of unknown characters in the participant group. Patients with schizophrenia spontaneously rated their dream reports as being less bizarre than did controls, despite a similar density of bizarre elements as scored by external judges. Finally, both groups had a comparable density of rapid eye movements during REM sleep but a significant positive correlation between eye-movement density and dream content variables was only found in controls. Taken together, the findings suggest that dream content characteristics in schizophrenia may reflect neurocognitive processes, including emotional processing, specific to this disorder. [Copyright &y& Elsevier]

Abstract: Objectives: We investigated event-related potentials time locked to the onset and offset of rapid eye movements during rapid eye movement (REM) sleep. Method: Nine healthy university students participated in this study. Data were collected in a sleep laboratory. Rapid eye movements during REM sleep were recorded during natural nocturnal sleep. Saccades during wakefulness were recorded during a visually triggered task. Event-related potentials were averaged, time-locked to the onset and offset of eye movements. Results: During REM sleep, a lambda-like response occurred over the occipital region, time-locked to the offset of rapid eye movements (similar to what occurs during wakefulness). Moreover, we found that a positive potential (P200r) occurred at about 200ms, with the maximal amplitude over the central region and time-locked to the onset of rapid eye movements during REM sleep; this potential was not observed during wakefulness. Conclusions: During REM sleep, the P200r occurs with the start of rapid eye movements, and then the lambda-like response occurs after termination of the movements. Significance: We demonstrated temporal coupling of rapid eye movements and cerebral activities during REM sleep. These activities might provide a useful basis for future investigations of brain functions during REM sleep. [Copyright &y& Elsevier]

Abstract: The aim of this study was to investigate the frequency of recall and the content of dreams during pregnancy, as well as their correlation with socio-demographic, obstetric and physician–patients relationship variables, emotional state and duration of labour. A questionnaire, designed to analyse background characteristics, was given to 290 women in the third trimester of gestation. The psychiatric analysis of anxiety and depression was performed using the Hamilton Rating Scale for Anxiety and the Montgomery–Åsberg Depression Rating Scale, while dreams were divided into masochistic and pleasant according to Beck''s criteria. Oneiric activity was found to be associated with age≥35 years, higher family income, higher educational level, and a “satisfactory” physician–patient relationship. Masochistic content was associated with age<35 years, quality of information and frequent thoughts of delivery. Concerning the emotional state, depression levels were higher in women reporting masochistic dreams, while no difference in anxiety levels was found. Labour duration was shorter in the dreamer group and in patients with masochistic dream content. These findings may indicate that, also in pregnancy, the number and the content of dreams are influenced by women''s mood and that the evaluation of the oneiric activity might represent a useful tool for clinicians either to investigate the women''s emotional state or to predict its repercussions on the course of labour. [Copyright &y& Elsevier]

Abstract: There has been an abundance of literature devoted to the involvement of noradrenaline in basic rapid eye movement (REM) sleep processes since the subject was first investigated in 1964. Nowadays, the great majority of studies highlight the need for silence in the locus coeruleus noradrenergic neurons as a condition for the occurrence and maintenance of REM sleep. However, throughout the successive years of work on this topic, few researchers have consistently claimed that some amount of noradrenaline is essential for the appearance of this sleep stage. In the first part of this review, each of the papers published in this field is analyzed. Then, in the discussion, arguments supporting the requirement for a given level of noradrenaline for REM sleep occurrence are presented. This second part also examines, based on waking noradrenergic influences on higher integrated brain processes, the major consequences of noradrenergic neuron silence during REM sleep for mental functioning. [Copyright &y& Elsevier]

Dreaming during anaesthesia is defined as any recalled experience (excluding awareness) that occurred between induction of anaesthesia and the first moment of consciousness upon emergence. Dreaming is a commonly-reported side-effect of anaesthesia. The incidence is higher in patients who are interviewed immediately after anaesthesia (approximately 22%) than in those who are interviewed later (approximately 6%). A minority of dreams, which include sensory perceptions obtained during anaesthesia, provide evidence of near-miss awareness. These patients may have risk factors for awareness and this type of dreaming may be prevented by depth of anaesthesia monitoring. Most dreaming however, occurs in younger, fitter patients, who have high home dream recall, who receive propofol-based anaesthesia and who emerge rapidly from anaesthesia. Their dreams are usually short and pleasant, are related to work, family and recreation, are not related to inadequate anaesthesia and probably occur during recovery. Dreaming is a common, fascinating, usually pleasant and harmless phenomenon. [ABSTRACT FROM AUTHOR]

Abstract: Animal models are a promising method to approach the basic mechanisms of the neurobiological disturbances encountered in mental disorders. Depression is characterized by a decrease of REM sleep latency and an increase of rapid eye movement density. In schizophrenia, electrophysiological, tomographic, pharmacological and neurochemical activities are all encountered during REM sleep. Mental retardation and dementia are characterized by rather specific REM sleep disturbances. Identification of the genetic support for these abnormalities (endophenotypes) encountered during REM sleep could help to develop specific treatments. [Copyright &y& Elsevier]

Abstract: Sleep may positively influence declarative memory through the processing, which transforms items of declarative knowledge into contents of mental sleep experience (MSE). A prediction from this general hypothesis is that the consolidation level should be higher for the output of items repeatedly processed and transformed into identical or very similar (so-called interrelated) contents of distinct MSEs of the same night rather than for the output of items presumably processed once (that is, all other, non-interrelated contents). Two experiments examined whether and how far the frequency and long-term retention of interrelated contents depend on the repeated processing of given items rather than on the experimental procedure applied for detection of interrelated contents. This procedure entails both multiple awakenings and a verbal report of MSE after awakening. Multiple awakenings could facilitate the re-access and elaboration of some contents into the subsequent (i.e. contiguous) MSE rather than non-contiguous MSEs; verbal reports could enhance the delayed recall of interrelated contents in as much as repeatedly encoded. The first experiment showed that interrelated contents were more frequent and better retained than both non-interrelated and pseudo-interrelated (i.e. by-chance similar or identical) contents, and even more in pairs of contiguous than non-contiguous MSEs collected from the first four periods of REM sleep on each experimental night. The second experiment showed that the frequency and retention rate of interrelated contents, while higher than those of non-interrelated and pseudo-interrelated contents, were not significantly different in pairs of MSEs which were verbally or mentally recalled after awakening provoked during the first four periods of REM sleep in each experimental night. Taken together, these findings indicate that the advantage provided by repeated processing during REM sleep for the consolidation of the output of items of declarative knowledge is conspicuous and largely independent from the experimental procedure, as this only slightly enhances the frequency and retention rate of interrelated contents. [Copyright &y& Elsevier]

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 aware that integrating dreams into their clinical practice is both accessible and potentially valuable and to allow them to make an informed decision as to what role they want dream work to play in therapy. The paper begins with a brief overview of some of the more common approaches to dream work. The literature on the usefulness and effectiveness of the clinical use of dreams is then reviewed. Finally, based on the integration of the clinical and empirical literature, several guidelines for conducting dream work are presented. [Copyright &y& Elsevier]

Brain function is supported by central activating processes that are significant during waking, decrease during slow wave sleep following waking and increase again during paradoxical sleep during which brain activation is as high as, or higher than, during waking in nearly all structures. However, inhibitory mechanisms are crucial for sleep onset. They were first identified by behavioral, neuroanatomical and electrophysiological criteria, then by pharmacological and neurochemical ones. During slow wave sleep, they are supported by GABAergic mechanisms located at midbrain, mesopontine and pontine levels but are induced and sustained by forebrain and hindbrain influences. GABAergic processes are also responsible for paradoxical sleep occurrence, particularly by suppression of noradrenaline and serotonin (5-HT) inhibition of paradoxical sleep-generating structures. Hindbrain and forebrain modulate these structures situated at the mesopontine level. For sleep mentation, the noradrenergic and serotonergic silence is thought, today, to be directly, or indirectly, responsible for dopamine predominance and glutamate decrease in the nucleus accumbens, which could be the background of the well-known psychotic-like mental activity of dreaming. [Copyright &y& Elsevier]

To examine the relationship between the emotional quality of dreams, REM sleep variables and suicidal tendency in depressed individuals, 26 depressed volunteers (10 males and 16 females) were assessed with the Beck Depression Inventory (BDI) and the Hamilton Depression Rating Scale (HDRS), and underwent 3 nights of polysomnography. There was a significant negative correlation between suicidality scores and REM latency and a positive correlation between suicidality and REM percent. Suicidal subjects had a significantly shorter mean REM latency and a higher mean REM percentage than the non-suicidal subjects. As expected in normal subjects, 20 subjects had an increase in dream-like quality (DLQ) of REM reports between the first and second halves of the night. The six subjects with a negative DLQ difference also scored as suicidal. A reduction in dream-like quality of the REM content reports between the first and second halves of the night was found to be associated with suicidal tendency. The findings may indicate that these subjects fail to self-regulate mood and integrate affect into long-term memory networks during sleep. Theoretical and clinical implications of these findings in depression are discussed. [Copyright &y& Elsevier]