Journal of Sleep Research
February 1, 2019
Erin J. Wamsley, Robert Stickgold
Dreaming about a spatial learning task during sleep predicts improved performance the next morning. In an overnight study, people trained on a virtual maze navigation task reported dreams from all sleep phases that reflected the task. Unambiguous representation of the task in dream content was associated with better next-morning performance. These findings align with models of memory consolidation that propose memory traces are reactivated during sleep, and replicate earlier work showing that dreaming about a learning task during a nap predicted performance gains.
Journal of Sleep Research
February 1, 2019
Sarah F. Schoch, Maren J. Cordi, Michael Schredl et al.
Awakenings to collect dream reports impair subjective and objective sleep quality but do not affect sleep-associated memory consolidation in a word-picture association learning task. Memories of the learning task are successfully incorporated into dreams collected during the night, but not into morning dream reports. Incorporation into non-rapid eye movement sleep dreams, but not rapid eye movement sleep dreams, positively predicts memory performance the next morning. The findings suggest that awakenings are a suitable method for dream and memory studies, and that non-rapid eye movement sleep dreams may be more related to memory consolidation processes than rapid eye movement sleep dreams.
Journal of Sleep Research
October 1, 2018
Raphael Vallat, Mickael Eskinazi, Alain Nicolas et al.
French college students spend about 8 hours in bed on weekdays and 9 hours on weekends, with 90.9% reporting no difficulty falling asleep. Dream recall averages about 3 mornings per week, positively linked to dream clarity and lucid dreaming frequency, and negatively linked to age. Nearly 7% report regular sleep-talking, while less than 0.4% have regular sleepwalking. Frequent lucid dreams occur in 14% of students, and recurrent dreams in 6%. Women report higher dream recall and more time in bed than men. Humanities students spend more time in bed than science students, suggesting a link between academic discipline and sleep duration.
Journal of Sleep Research
October 1, 2018
Dan Denis, Christopher C. French, Melanie N. Schneider et al.
Poor sleep quality is linked to sleep paralysis, but the precise nature of the relationship is unclear. This study analyzed data from 860 individuals aged 22–32 years (66% female) from the G1219 twin/sibling study. Two components of the Pittsburgh Sleep Quality Index—sleep latency and daytime dysfunction—predicted sleep paralysis. Additional factors associated with sleep paralysis included insomnia symptoms, sleep problems related to traumatic experiences, presleep arousal, unhelpful thoughts about sleep, and excessive daytime sleepiness. No relationship was found with sleep-disordered breathing, diurnal preference, or sleeping arrangements. The results suggest that improving specific aspects of sleep quality might help reduce sleep paralysis episodes.
Journal of Sleep Research
April 1, 2018
Pilleriin Sikka, Antti Revonsuo, Nils Sandman et al.
Dreams collected at home upon morning awakening are more emotional and more negative than those collected in the lab after early REM sleep awakenings, but not more emotional than those after late REM awakenings. Home dreams also contain a higher density of emotions than lab dreams from either early or late REM sleep. The differences in overall emotionality may be due to the time of night, while the causes of differences in emotion density and negativity—whether from the sleep environment, reporting procedures, or time spent in a sleep stage—remain unclear.
Journal of Sleep Research
December 1, 2015
Bastien Herlin, Smaranda Leu-Semenescu, Charlotte Chaumereuil et al.
People who report never dreaming actually do produce dreams but fail to recall them. Among 289 patients with rapid eye movement sleep behaviour disorder (RBD), a condition where people act out their dreams, eight (2.8%) reported no dream recall for at least 10 years, including four who had never recalled a dream in their lifetime. Despite this, all eight non-recallers exhibited daily or near-nightly complex, scenic, dreamlike behaviours and speeches during REM sleep, such as arguing, fighting, and speaking, both by report and on video-polysomnography. They did not recall dreams even after sudden awakenings from REM sleep. These non-recallers did not differ cognitively, clinically, or in sleep measures from matched dream-recallers with RBD. The findings provide strong evidence that non-recallers produce dreams but do not recall them.
Journal of Sleep Research
August 1, 2015
Gaëlle Dumel, Michelle Carr, Louis-Philippe Marquis et al.
People who habitually recall few dreams performed worse on a visuomotor task (mirror tracing) before sleep but showed greater overnight improvement than those who recall many dreams. The improvement in low recallers was linked to Stage 2 sleep rather than rapid eye movement sleep. The findings suggest that dreaming relates to visuomotor processes and that different levels of visuomotor skill engage distinct sleep-related consolidation mechanisms.
Journal of Sleep Research
April 1, 2015
Carlo Cipolli, Mario Guazzelli, Claudia Bellucci et al.
Dream reports collected from 14 participants after planned awakenings during REM sleep show that story-like organization depends on both time of night and REM duration. Reports from the 4th sleep cycle were longer than those from the 2nd, and reports after 10 minutes of REM were nearly significantly longer than after 5 minutes. The number of dream-stories per report did not change, but the sequential and hierarchical complexity of individual dream-stories increased only after 10 minutes of REM in the 4th cycle. These results indicate that building a long, coherent dream narrative requires sufficient time and cognitive resources.
Journal of Sleep Research
February 9, 2015
Dan Denis, C. French, R. Rowe et al.
Sleep paralysis is moderately heritable (53%) in a UK sample of 862 twins and siblings aged 22–32 years. Poor sleep quality, anxiety symptoms, and exposure to threatening events were each independently associated with sleep paralysis. Variants in the PER2 gene showed some association, but this did not survive correction for multiple testing. The authors conclude that factors disrupting sleep cycles appear linked to sleep paralysis and that future research should explore circadian-rhythm and sleep-homeostasis polymorphisms.
Journal of Sleep Research
June 1, 2012
Sarah L Chellappa, Mirjam Münch, Vera Knoblauch et al.
Older adults show distinct brain activity patterns during sleep that are linked to whether they recall a dream. Compared with young people (20-31 years), older volunteers (57-74 years) had higher frontal delta and centro-parietal sigma activity during non-rapid eye movement (NREM) sleep before dream recall, but lower frontal-central delta and sigma activity before no recall. During REM sleep, older participants had less frontal-central alpha and beta activity regardless of recall. The findings suggest age-related differences in dream recall are directly tied to specific EEG frequency and brain-region patterns, especially during NREM sleep.
Journal of Sleep Research
February 1, 2012
Caroline Kusse, Anahita Shaffii-LE Bourdiec, Jessica Schrouff et al.
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Journal of Sleep Research
September 1, 2011
Jaap Lancee, Victor I. Spoormaker, Jan Van den Bout
Two cognitive-behavioural self-help interventions for nightmares, imagery rehearsal and exposure, produced effects that were almost completely sustained 42 weeks after treatment ended. The initial improvements in nightmare measures persisted with effect sizes between 0.50 and 0.70. No differences in effectiveness were found between the two interventions. These long-term results suggest that nightmares can be effectively treated with targeted self-help approaches, and an internet-delivered intervention may serve as a good first step in a stepped-care model.
Journal of Sleep Research
December 1, 2008
E J O Kompanje
A 1664 case report by Dutch physician Isbrand Van Diemerbroeck describes a 50-year-old woman's nightly experiences that match modern criteria for sleep paralysis accompanied by hypnagogic hallucinations. This is the earliest detailed account of sleep paralysis associated with hypnagogic illusions and the first observation that these phenomena occur more often when the body is in a supine position.
Journal of Sleep Research
June 1, 2008
Michael Schredl, Iris Reinhard
Women tend to recall their dreams more often than men, and this difference varies with age. An analysis of 175 independent studies found that the smallest gender difference occurs in children (effect size 0.097), the largest in adolescents (0.364), and moderate differences in adults (0.242 to 0.270). The pattern suggests that gender-specific 'dream socialization' may explain why the gap emerges and changes across the lifespan, though longitudinal studies are still lacking.
Journal of Sleep Research
September 1, 2007
Mariana Szklo‐coxe, Terry Young, Laurel Finn et al.
Depression is strongly associated with rapid eye movement-related sleep disturbances, particularly sleep paralysis, even after accounting for anxiety. In a community sample of 866 adults, severe depression increased the odds of sleep paralysis by about 500%. Depression also raised the odds of cataplexy in non-anxious participants nine-fold, but not in anxious ones. Anxiety partially explained depression's link to hypnagogic/hypnopompic hallucinations and was more related than depression to automatic behavior. Insomnia and sleepiness only partly mediated these associations. Recognizing these often-neglected sleep disturbances may help characterize depression more fully.
Journal of Sleep Research
June 1, 2006
Todd A. Girard, J. Allan Cheyne
Sleep paralysis episodes occur most often in the first two hours after going to bed, with just over a quarter happening within the first hour, though episodes can occur throughout the night with a smaller peak near normal waking time. The timing of episodes is consistent for individuals across different nights and does not depend on what time they go to bed. The results support the idea that sleep paralysis timing is controlled by processes that start at or after sleep onset and suggest that sleep paralysis may result from failing to maintain sleep during REM periods at any point in the night, rather than only at sleep onset.
Journal of Sleep Research
September 1, 2005
J. A. Cheyne
Sleep paralysis hallucinations fall into three categories thought to stem from REM sleep processes, but prior studies mixed people with different levels of experience. This survey of 5,799 current sleep paralysis experiencers compared novice and frequent experients. Hallucination types and variety differed with episode frequency, yet the three-factor structure remained consistent across groups. Novices showed clearer separation between hallucination types, while frequent experients tended to blend experiences across episodes. Earlier onset of sleep paralysis was linked to more frequent episodes. The findings support the idea that the basic organization of sleep paralysis hallucinations arises from intrinsic REM-related processes, independent of prior experience.
Journal of Sleep Research
December 1, 2004
Carlo Cipolli, Igino Fagioli, Michela Mazzetti et al.
Presleep stimuli are often incorporated into dream contents. A study of 12 participants tested whether such incorporation improves memory consolidation. Participants memorized nonsense sentences before each sleep onset during a night, reported dreams and recalled sentences after each REM awakening, and gave unexpected morning reports. Dream reports were parsed into content units. Night reports more often contained valid incorporations than pseudo-incorporations. Content units common to night and morning reports—indicating better consolidation—were significantly more frequent for incorporated contents than for other contents. However, recall of words from incorporated sentences was not significantly better. The findings partially support a generation effect operating during sleep, benefiting retention of actively processed information.
Journal of Sleep Research
September 1, 2002
Troels W Kjaer, Ian Law, Gordon Wiltschiøtz et al.
During stage-1 sleep (somnolence), regional cerebral blood flow increases in the occipital lobes and decreases in the bilateral cerebellum, bilateral posterior parietal cortex, right premotor cortex, and left thalamus, compared to the awake relaxed state. Hypnagogic hallucinations were not associated with measurable blood flow changes. The occipital activation supports stage-1 sleep as a state of imagery, while blood flow decreases in premotor cortex, thalamus, and cerebellum suggest reduced preparedness for goal-directed action. Stage-1 sleep appears more similar to altered awareness states like relaxation meditation than to deeper sleep, and may represent the dreaming state of wakefulness, distinct from REM sleep dreaming.
Journal of Sleep Research
June 1, 2002
J. A. Cheyne
Sleep paralysis (SP) is a temporary inability to move or speak when waking up or falling asleep, often accompanied by frightening hallucinations. Two studies involving 6730 subjects, including 4699 who had experienced SP, examined how body position and timing affect SP. More individuals reported SP while lying on their back (supine) than in all other positions combined. The supine position was three to four times more common during SP than during normal sleep. SP episodes occurring in the middle or at the end of sleep were more likely to involve the supine position than those at the beginning, suggesting later episodes may arise from brief awakenings during REM sleep possibly triggered by apnea.
Journal of Sleep Research
June 9, 2001
Patrick Mcnamara, Jensine Andresen, Jill Clark et al.
People with insecure attachment styles are more likely to recall dreams and report more intense, emotional dream imagery than those with secure attachment. In one study, college students high on an insecure attachment scale reported more frequent dreams and stronger emotional content than those low on the scale. In a second study of 76 older adults, those with a 'preoccupied' attachment style recalled dreams more often and with more words than those with secure, avoidant, or dismissing styles. Avoidant participants had the lowest dream recall. The findings suggest that REM sleep and dreaming may help support attachment processes.
Journal of Sleep Research
June 1, 2001
E F Pace-Schott, T Gersh, R Silvestri et al.
Selective serotonin reuptake inhibitors (SSRIs) such as paroxetine and fluvoxamine affect dreaming in distinct ways. In 14 healthy volunteers, dream recall frequency decreased during treatment compared to baseline, while subjective dream intensity increased during both treatment and acute discontinuation. Dream report length and bizarreness, as rated by judges, increased during acute discontinuation, particularly in those taking fluvoxamine. REM sleep propensity decreased during treatment, while REM sleep intensity increased during discontinuation. The findings suggest that decreased dream frequency during SSRI treatment may reflect serotonergic suppression of REM sleep, whereas increased dream length and bizarreness during discontinuation may reflect cholinergic rebound.
Journal of Sleep Research
December 1, 1999
J. Allan Cheyne, Ian R. Newby‐Clark, Steve D. Rueffer
A new scale, the Waterloo Sleep Experiences Scale, measures the prevalence of sleep paralysis and related hallucinoid experiences such as sensed presence, pressure, floating, and auditory or visual hallucinations. Among 870 university students, nearly 30% reported at least one sleep paralysis episode. About three-quarters of those also reported hallucinoid experiences, and over 10% experienced three or more. Fear was positively linked to hallucinoid experiences, especially sensed presence. Regression analyses suggest that sensed presence and fear are basic features of sleep paralysis that may lead to further hallucinoid experiences, particularly visual ones.
Journal of Sleep Research
June 1, 1999
Yun Kwok Wing, Helen Chiu, Tony Leung et al.
Isolated sleep paralysis, known as 'ghost oppression' in Hong Kong, is common among Chinese elderly over age 70. In a sample of 158 subjects, nearly 18% reported experiences of ghost oppression, with descriptions closely matching sleep paralysis. Onset showed a clear bimodal distribution, with peaks in adolescence and after age 60; at least one-third of cases began late in life. Those with ghost oppression also reported more frequent nocturnal sleep disturbances, consistent with the REM/wakefulness dissociation hypothesis. A family history was reported in 10% of subjects.
Journal of Sleep Research
September 1, 1998
Michael Schredl, Gerard Schäfer, Bettina Weber et al.
People with insomnia recall their dreams more often than healthy individuals, mainly because they wake up more frequently during the night. Their dream content tends to be more negative, with themes of depression, self-criticism, and health concerns, reflecting waking-life stressors. Antidepressant use is linked to lower dream recall, while benzodiazepines do not affect recall frequency. Both types of medication are associated with more positively toned dreams compared to unmedicated patients. The authors recommend future studies collect more dreams per person to improve measurement accuracy and include detailed assessments of waking stress.