Dream Recall Research Articles

Studying the relationship between dreaming and sleep-dependent memory processes: Methodological challenges

The hypothesis that dreaming is involved in off-line memory processing is difficult to test because major methodological issues have to be addressed, such as dream recall and the effect of remembered dreams on memory. It would be fruitful--in addition to studying the ancient art of memory (AAOM) in a scanner--to study the dreams of persons who use AAOM regularly.

Exploring Telicity and Transitivity in Primordial Thought Language and Body Boundary Imagery

Linguistics research on 'unconscious knowledge' related to the right brain-hemisphere represents a shift from the prevalent scientific investigation of the linguistic processes of grammatical structures associated with the dominant 'verbal' left brain-hemisphere. This study explores the relationship among primordial thought language, body boundary awareness and syntactic features--i.e., telicity, perfectivity and transitivity-in autobiographical narratives of everyday and dream memories. The results showed that event descriptions with atelic predicates and intransitive structures were more frequent in dream recall than in narratives of everyday memories. Primordial thought language and body boundary awareness, however, decreased with atelic predicates and transitive structures, which might indicate both the tendency of events to describe result states, such as achievements and accomplishments, as a means to bring about an unconscious wish fulfilment and the emphasis on event arguments to be realised without the inclusion of an external object. In narratives of everyday memories, penetration imagery increased with imperfective verb forms and decreased with perfective verb forms, and emotion lexis increased with atelic predicates and transitive structures, but not in dream memories.

Stage-dependent cortical/hippocampal reactivation may explain the differences in recall frequency between REM and NREM mentation

Previous research has demonstrated that dream recall rates differ between REM and NREM sleep. However, the neurological mechanisms responsible for this difference are not fully understood. Here recent research is discussed regarding the characteristics of neural reactivation during REM and NREM in response to pre-sleep memory acquisition. It is proposed that differential reactivation of cortical and subcortical areas during REM and NREM may offer one possible explanation for why there are differences in dream recall rates from REM and NREM sleep.

Incidence and frequency of lucid dreams in a Swiss junior college student sample

This study was conducted to inspect the incidence of lucid dreaming within a Swiss junior college student sample. Out of 214 participants, 50% had experienced at least one lucid dream, while 26% were frequent lucid dreamers with a lucid dream frequency equal to or higher than once a month. The term lucid dream or the German synonym “Klartraum” was known by 31%. Lucid dream frequency and dream recall frequency were significantly related. The results imply a prevalence of lucid dreams similar to that in Germany. For further comparison a representative Swiss study would be needed.

Religious Worship and Dream Recall: New Results from a Survey of American Adults

This study of 2,992 demographically diverse American adults provides a new empirical view of the relationship between dreams and religion. Participants answered a question about the frequency of their religious worship service attendance, in addition to several questions about their recall of various types of dreams. The results confirm previous research showing that the most religiously observant people in America tend to remember considerably fewer dreams than do the least religiously observant people. This study elaborates on that finding by using word search technology to analyze several hundred dream reports provided by the participants. The results show that in terms of dream content, there is little difference between religiously observant and nonobservant people, other than a higher frequency of Christianity-related words in the dreams of the most religiously observant people. This study gives pastoral caregivers and psychotherapists new insights into the religiously and spiritually meaningful patterns they may encounter in the dreams of their clients.

Nightmare Frequency, Nightmare Distress, and Psychopathology in Female Victims of Childhood Maltreatment

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, psychological well-being, and history of childhood trauma. Four groups were investigated based on the type and severity of childhood maltreatments experienced. Women reporting more severe forms of maltreatment reported higher frequencies of disturbing dreams, higher levels of nightmare distress, and greater psychopathology. Results showed that nightmare distress explains frequency of disturbed dreaming beyond the effect of psychopathology and childhood trauma. The results highlight the importance of assessing waking distress associated with disturbing dreams independently from their actual incidence.

Stress-related biomarkers of dream recall and implicit memory under anaesthesia

The aim of this study was to investigate whether auditory presentation of a story during general anaesthesia might influence stress hormone changes and thus affecting dream recall and/or implicit memory. One hundred and ten patients were randomly assigned either to hear a recording of a story through headphones or to have routine care with no auditory recording while undergoing laparoscopic cholecystectomy. Anaesthesia was standardised. Blood samples for cortisol and prolactin assays were collected 20 min before anaesthesia and 5 min after pneumoperitoneum. Dream recall and explicit/implicit memory were investigated upon awakening from anaesthesia and approximately 24 h after the end of the operation. Auditory presentation was associated with lower intra-operative serum prolactin concentration compared with control (p = 0.0006). Twenty-seven patients with recall of dreaming showed higher intra-operative prolactin (p = 0.004) and lower cortisol (p = 0.03) concentrations compared with those without dream recall. The knowledge of this interaction might be useful in the quest to ensure postoperative amnesia.

Is recall of dreaming during anesthesia a sign of occurrence of postoperative nausea and vomiting?

We examined the relationships between recall of dreaming during anesthesia and postoperative nausea and vomiting (PONV). We found a relationship between PONV within 24 h and age <50 years, use of postoperative epidural analgesia with morphine, and female gender. We also found a relationship between PONV lasting more than 24 h and dream recall. As serotonin plays an important role for both inducing PONV and dream recall, results of the present study may suggest a possible relationship between dream recall and PONV.

Does training increase NREM dream recall? A pilot study

The percentages of successful dream recall vary depending on whether the participants were awakened from REM sleep (about 80% recall) or NREM sleep (about 50% recall). The question as to whether this difference is explained by less dreaming during NREM sleep or sleep state-dependent memory processes cannot answered easily. The present pilot study was designed to test whether high recallers can increase their NREM dream recall to figures equal to those obtained from REM awakenings. The participants were awakened during NREM on three non-consecutive nights while training in dream recall by keeping a dream diary. Even though the study’s goal was not achieved, the findings support the hypothesis that dreaming is always present during NREM sleep and that reduced NREM recall percentages are explained by sleep stage-dependent recall processes. Future research should focus on these sleep stage-dependent recall processes and correlate possible interindividual differences with their differences in dream recall.

Gender differences in dream socialisation in children and adolescents

Dream socialisation encompasses factors that might affect children's attitudes towards dreams or their dream recall frequencies directly; for example, by being asked about dreams by other persons or the sharing of dreams with others. The present study in 170 children/adolescents (age range 10–15 years) was designed to study whether dream socialisation might help to explain the well-documented gender difference regarding dream recall frequencies and related variables in adolescence and adulthood. Gender-specific effects regarding the frequency of communicating about dreams, especially for same-sex friendships, were found, and the correlation supports the hypothesis that these variables might be of importance to dreaming in later life. In order to corroborate the results of this first quantitative study of dream socialisation in children/adolescents, longitudinal studies as well as experimental studies manipulating dream socialisation variables are necessary.

The Baroque and its influence on Willis’ description of restless legs syndrome

(103 ng/mL; reference range, 15–200 ng/mL). To our knowledge, there is no previous report of RLS symptoms occurring after lucid dreams, and there are few descriptions of dream studies in the RLS population. Schredl [4] studied dream recall frequenc y in 131 patients with RLS, and he did not find increased dream recall frequency compared to healthy controls. The author speculated that frequent arousals associated with periodic limb movements might interfere with dream recall or the dreaming process [4]. Further studies are needed to investigate the correlation between RLS, content, and physiology of dreaming as well as and periodic limb movements in sleep.

Brain Reactivity Differentiates Subjects with High and Low Dream Recall Frequencies during Both Sleep and Wakefulness

The neurophysiological correlates of dreaming remain unclear. According to the "arousal-retrieval" model, dream encoding depends on intrasleep wakefulness. Consistent with this model, subjects with high and low dream recall frequency (DRF) report differences in intrasleep awakenings. This suggests a possible neurophysiological trait difference between the 2 groups. To test this hypothesis, we compared the brain reactivity (evoked potentials) of subjects with high (HR, N = 18) and low (LR, N = 18) DRF during wakefulness and sleep. During data acquisition, the subjects were presented with sounds to be ignored (first names randomly presented among pure tones) while they were watching a silent movie or sleeping. Brain responses to first names dramatically differed between the 2 groups during both sleep and wakefulness. During wakefulness, the attention-orienting brain response (P3a) and a late parietal response were larger in HR than in LR. During sleep, we also observed between-group differences at the latency of the P3a during N2 and at later latencies during all sleep stages. Our results demonstrate differences in the brain reactivity of HR and LR during both sleep and wakefulness. These results suggest that the ability to recall dreaming is associated with a particular cerebral functional organization, regardless of the state of vigilance.

Alpha reactivity to first names differs in subjects with high and low dream recall frequency.

Studies in cognitive psychology showed that personality (openness to experience, thin boundaries, absorption), creativity, nocturnal awakenings, and attitude toward dreams are significantly related to dream recall frequency (DRF). These results suggest the possibility of neurophysiological trait differences between subjects with high and low DRF. To test this hypothesis we compared sleep characteristics and alpha reactivity to sounds in subjects with high and low DRF using polysomnographic recordings and electroencephalography (EEG). We acquired EEG from 21 channels in 36 healthy subjects while they were presented with a passive auditory oddball paradigm (frequent standard tones, rare deviant tones and very rare first names) during wakefulness and sleep (intensity, 50 dB above the subject's hearing level). Subjects were selected as High-recallers (HR, DRF = 4.42 ± 0.25 SEM, dream recalls per week) and Low-recallers (LR, DRF = 0.25 ± 0.02) using a questionnaire and an interview on sleep and dream habits. Despite the disturbing setup, the subjects' quality of sleep was generally preserved. First names induced a more sustained decrease in alpha activity in HR than in LR at Pz (1000–1200 ms) during wakefulness, but no group difference was found in REM sleep. The current dominant hypothesis proposes that alpha rhythms would be involved in the active inhibition of the brain regions not involved in the ongoing brain operation. According to this hypothesis, a more sustained alpha decrease in HR would reflect a longer release of inhibition, suggesting a deeper processing of complex sounds than in LR during wakefulness. A possibility to explain the absence of group difference during sleep is that increase in alpha power in HR may have resulted in awakenings. Our results support this hypothesis since HR experienced more intra sleep wakefulness than LR (30 ± 4 vs. 14 ± 4 min). As a whole our results support the hypothesis of neurophysiological trait differences in high and low-recallers.

Dream Content Alalysis at the Initiation of CPAP for Obstructive Sleep Apnea

Obstructive Sleep Apnea Hypopnea Syndrome (OSAHS) is a condition characterized by repeated episodes of airway obstruction during sleep, causing intermittent asphyxia and sleep fragmentation. The goal of this study was to assess dream content analysis before and during the first night of treatment for OSAHS using Continuous Positive Pressure (CPAP). We included 38 patients diagnosed using complete overnight polysomnography (PSG), who received CPAP therapy during a second night under PSG. Dream content (word count, thematic units, and emotional content) and the percent of REM sleep were analyzed after both nights. There was an increase in the percent of REM under CPAP (from 16,7% to 26,8%). There was an increase in the number of thematic units (1,36 without CPAP versus 1,82 under CPAP) and in the word count (30,52 without CPAP versus 45,22 under CPAP) and a change in the dream content (unpleasant content in 50% without CPAP versus 37,5% under CPAP). Under CPAP, more patients recalled their dreams than without CPAP (94,2% versus 57,9%). In conclusion, at the initiation of CPAP for OSAHS, there is a rebound of REM sleep associated with a quantitative increase in dream recall and a change in dream content.

Sleep and Cognition in the Elderly

In the past decade, our understanding of sleep mechanisms and their role in cognitive processes including memory functions has markedly increased. However, most data have been gathered in young adults, neglecting the fact that sleep is an age-dependent evolutionary process featuring substantial physiological changes that may impact on daily cognitive functioning. Despite the importance of this topic from scientific and societal standpoints, studies jointly investigating aging, sleep, and cognition remain scarce, even considering patients with neurodegenerative diseases. With this special topic, we aim at providing the reader with an updated overview of those studies assessing the impact of age-related changes in sleep and sleep regulation on various domains of cognition. In this respect, this issue addresses changes in sleep and circadian rhythms in the elderly, and how they impact on cognitive performance and brain activity (Schmidt et al., 2012). Sleep-dependent memory consolidation and the age-related changes that may compromise this complex process are also discussed (Harand et al., 2012), as well as how pre-sleep learning can improve sleep continuity, stability, and organization in older adults (Conte et al., 2012). Considering mental productions during sleep, variations in dream recall frequency, and dream theme diversity across the lifespan are also investigated (Nielsen, 2012). From another perspective, the potential mechanisms underlying sleep changes in adults are investigated, focusing on the role of adenosine in protecting from neurobehavioral impairments after sleep deprivation in older adults (Landolt et al., 2012) and on age-related changes in slow oscillations during sleep-dependent memory consolidation processes (Fogel et al., 2012). Finally, common sleep-related pathologies are addressed. In the context of aging, insomnia complaints in older adults and its neural substrates are a crucial issue (Stoffers et al., 2012), but elderly are also a population at risk for obstructive sleep apnea, which might markedly impact on cognitive processes (Sforza and Roche, 2012). Also, less frequent in isolation in normal aging but commonly associated with dementia with Lewy bodies or Parkinson's disease, REM sleep behavior disorder may accelerate cognitive decline (Gagnon et al., 2012). Altogether, the contributions in this issue show that a better understanding of age-related changes in sleep architecture and microstructure, of their potential impact on cognition and of their underlying mechanisms is essential to develop efficient care of sleep disturbances in the elderly. Such information is even more crucially needed to better apprehend and treat sleep disturbances in neurodegenerative diseases, such as Alzheimer's disease, where sleep disturbances, taken as downstream symptoms of the disease, can be evidenced years before the diagnosis. These sleep disturbances may significantly accelerate cognitive decline (e.g., Rauchs et al., 2008; Hot et al., 2011; Westerberg et al., 2012) and exacerbate the neuropathological processes leading to amyloid depositions (Kang et al., 2009; Ju et al., 2013). Hence it highlights the utmost importance of preserving sleep quality in older adults for optimal cognitive functioning and opposing to the course of neurodegenerative diseases.

Dream characteristics in a Brazilian sample: an online survey focusing on lucid dreaming

During sleep, humans experience the offline images and sensations that we call dreams, which are typically emotional and lacking in rational judgment of their bizarreness. However, during lucid dreaming (LD), subjects know that they are dreaming, and may control oneiric content. Dreaming and LD features have been studied in North Americans, Europeans and Asians, but not among Brazilians, the largest population in Latin America. Here we investigated dreams and LD characteristics in a Brazilian sample (n = 3,427; median age = 25 years) through an online survey. The subjects reported recalling dreams at least once a week (76%), and that dreams typically depicted actions (93%), known people (92%), sounds/voices (78%), and colored images (76%). The oneiric content was associated with plans for the upcoming days (37%), memories of the previous day (13%), or unrelated to the dreamer (30%). Nightmares usually depicted anxiety/fear (65%), being stalked (48%), or other unpleasant sensations (47%). These data corroborate Freudian notion of day residue in dreams, and suggest that dreams and nightmares are simulations of life situations that are related to our psychobiological integrity. Regarding LD, we observed that 77% of the subjects experienced LD at least once in life (44% up to 10 episodes ever), and for 48% LD subjectively lasted less than 1 min. LD frequency correlated weakly with dream recall frequency (r = 0.20, p < 0.01), and LD control was rare (29%). LD occurrence was facilitated when subjects did not need to wake up early (38%), a situation that increases rapid eye movement sleep (REMS) duration, or when subjects were under stress (30%), which increases REMS transitions into waking. These results indicate that LD is relatively ubiquitous but rare, unstable, difficult to control, and facilitated by increases in REMS duration and transitions to wake state. Together with LD incidence in USA, Europe and Asia, our data from Latin America strengthen the notion that LD is a general phenomenon of the human species.

Dream Recall Frequency and Unusual Dream Experiences in Early Adolescence: Longitudinal Links to Behavior Problems

Unique dream patterns are related to psychopathological distress in adults. In adolescence, this was investigated almost exclusively regarding nightmares. This longitudinal study examines developmental trajectories of various adolescent-reported dream patterns, and their associations with parent-reported psychopathology (internalization and externalization problems) in early adolescence. Ninety-four 10- to 11-year-old normally developing children completed a week of sleep, dreaming, and pubertal development assessments. Parents reported behavior problems. Assessments were repeated after 1 and 2 years. Reports of unusual dreams decreased over time, and dream recall decreased among girls. Internalizing symptoms longitudinally predicted an increase in dream recall and unusual dreams. Moreover, unusual dreams longitudinally predicted increased behavior problems (internalization and externalization). Assessing dream patterns during early adolescence may help early detection of covert psychopathological distress.

Presleep Self-Suggestion and Dream Recall: A Single-Subject Study

Dreaming is a universal human experience. Despite this universality, dreams are easily forgotten and home dream recall frequency varies considerably among individuals and within one individual from night to night. Investigation into the dream recall process remains a core issue in the field of dream research. Studies suggest that dream recall can be affected by presleep conditions and that presleep suggestions can influence dream content. This single-subject A/B experiment was conducted to test the hypothesis that dream recall would be enhanced using presleep self-suggestion. The results showed no increase in dream recall during the self-suggestion period. More research needs to be done before this question can be answered with any degree of confidence.

What physicians need to know about dreams and dreaming

An overview of the current status of dream science is given, designed to provide a basic background of this field for the sleep-interested physician. No cognitive state has been more extensively studied and is yet more misunderstood than dreaming. Much older work is methodologically limited by lack of definitions, small sample size, and constraints of theoretical perspective, with evidence equivocal as to whether any special relationship exists between rapid eye movement (REM) sleep and dreaming. As the relationship between dreams and REM sleep is so poorly defined, evidence-based studies of dreaming require a dream report. The different aspects of dreaming that can be studied include dream and nightmare recall frequency, dream content, dreaming effect on waking behaviors, dream/nightmare associated medications, and pathophysiology affecting dreaming. Whether studied from behavioral, neuroanatomical, neurochemical, pathophysiological or electrophysiological perspectives, dreaming reveals itself to be a complex cognitive state affected by a wide variety of medical, psychological, sleep and social variables.

Dream recall frequency: Impact of prospective measures and motivational factors

Significant individual differences exist in dream recall frequency (DRF) but some variance is likely attributable to instrument choice in measuring DRF. Three hundred and fifty eight participants estimated their weekly DRF and recorded their dreams in either a narrative log (n = 165) or checklist log (n = 193) for 2-5 weeks. There was an early peak in DRF within the first week of both types of prospective logs after which DRF remained relatively stable. Although the two groups did not differ in their estimated DRF, significantly fewer dreams were reported per week on the narrative logs and only checklist logs yielded significantly higher DRF than participants' questionnaire estimates. The interactions between DRF measures did not vary across groups with low, medium or high baseline levels of DRF. Keeping a dream log does not necessarily increase DRF and narrative logs' time consuming nature can impact subjects' motivation to report all of their dreams over time.