Sleep Medicine Reviews
June 8, 2017
Dan Denis, Christopher C. French, Alice M. Gregory
129 citations
Sleep paralysis is a common but poorly understood phenomenon. A systematic review of 42 studies identified multiple variables associated with its frequency and intensity, including substance use, stress and trauma, genetic influences, physical illness, personality, intelligence, anomalous beliefs, sleep problems and disorders, and psychiatric symptoms. Sleep paralysis is especially prevalent in post-traumatic stress disorder and, to a lesser degree, panic disorder. The review notes limitations in the current literature and suggests directions for future research and clinical practice.
Sleep Medicine Reviews
April 16, 2024
J.P. Delage, Jeannie Côté, William-Girard Journault et al.
22 citations
Insomnia and nightmares frequently co-occur and worsen each other. This systematic review of 67 studies found consistent positive links between insomnia and nightmares across diverse groups—people with insomnia or nightmares, general populations, students, children, older adults, military personnel, and veterans—even during the COVID-19 pandemic. People with insomnia also report more negative dream content and emotions than controls. Some interventions, like Imagery Rehearsal Therapy, may reduce both conditions. The authors propose a model where insomnia increases nightmare likelihood, and nightmares then cause sleep loss and nonrestorative sleep.
Sleep Medicine Reviews
October 1, 2023
Elissar El Sabbagh, Aviva N Johns, Christy E Mather et al.
Nightmares affect between 1% and 11% of school-aged youth in the past week and 25% to 35% in the past month in general developmental samples, while rates are higher in psychiatric samples, ranging from 27% to 57% in the past week and 18% to 22% in the past month. Nightmare disorder prevalence is about 3% to 6% in developmental samples and 10% to 12% in psychiatric samples. Nightmare frequency peaks between ages 10 and 14, then declines with older age, and is generally higher in girls than boys, with gender divergence starting around age 14. Children's self-reports yield higher prevalence than parent reports, except in psychiatric samples where agreement is greater. Inconsistent definitions and measurement methods across studies highlight the need for standardized assessment.
Sleep Medicine Reviews
April 1, 2020
Dilan E Yücel, Arnold A P Van Emmerik, Camille Souama et al.
A meta-analysis of 15 studies (N = 1,078) compared prazosin and imagery rehearsal therapy (IRT) for posttraumatic nightmares. Prazosin showed moderate to large effects on nightmare frequency, posttraumatic stress symptoms, and sleep quality, while IRT showed small to moderate effects. No significant differences were found between the two treatments on any outcome. The authors conclude that downgrading the recommendation for prazosin may be premature, as aggregated results show efficacy of both treatments.
Sleep Medicine Reviews
April 1, 2019
Valentina Alfonsi, Aurora D'Atri, Serena Scarpelli et al.
Sleep talking is a common, non-pathological behavior involving unaware vocalizations during sleep. Despite increased knowledge about sleep cognition, research on sleep talking remains outdated. Verbal utterances often reflect ongoing dream content, offering a direct window into dreamlike mental experiences. The phenomenon is discussed within a cognitive framework, considering atypical activation of psycholinguistic circuits during sleep and the role of verbal 'replay' in memory consolidation. Analyzing sleep talking episodes could help address fundamental questions about dreaming and information processing during sleep, though further systematic polysomnographic and neuroimaging studies are needed.
Sleep Medicine Reviews
February 1, 2019
P. Fazekas, G. Nemeth, M. Overgaard
White dreams—the feeling of having dreamed without recalling any content—account for nearly a third of all dream reports but have been largely ignored as forgotten dreams. This review argues that white dreams instead offer fundamental insights into the neural processes of the dreaming brain. Drawing on recent advances in dream research, mental imagery, and wakeful perception, the authors propose a new interpretation of white dreams and outline a general framework for the neural basis of conscious experience that extends beyond dreaming to the study of consciousness itself.
Sleep Medicine Reviews
October 1, 2017
Carlo Cipolli, Michele Ferrara, Luigi De Gennaro et al.
Recent advances in electrophysiological techniques, video-polysomnography, transcranial stimulation, and neuroimaging allow more accurate investigation of the neural correlates of dreaming in healthy individuals and patients with brain damage, neurodegenerative diseases, sleep disorders, or parasomnias. Convergent evidence has led to reformulation of unresolved issues of dream generation and recall within more comprehensive models of human consciousness. These studies are casting new light on the neural bases—particularly activity in dorsal medial prefrontal cortex, hippocampus, and amygdala—of inter- and intra-individual differences in dream recall, temporal location of dream content, and memory processing during sleep. Hd-EEG techniques appear able to provide further insights into how the brain generates dreaming and dreamlike waking experiences.
Sleep Medicine Reviews
August 1, 2016
Elena Antelmi, Raffaele Ferri, Alex Iranzo et al.
State dissociation disorders occur when features of one state of being—wakefulness, REM sleep, or NREM sleep—intrude into another. Examples include cataplexy, sleep paralysis, REM sleep behavior disorder, and disorders of arousal. The most extreme form, status dissociatus, involves a breakdown of all recognizable states; it can occur intermittently in conditions like narcolepsy type 1 or continuously in agrypnia excitata. This review classifies the full range of diseases and disorders associated with state dissociation and status dissociatus.
Sleep Medicine Reviews
April 1, 2015
Martin Dresler, Renate Wehrle, Victor I. Spoormaker et al.
Lucid dreaming, a rare sleep state where the dreamer becomes aware of dreaming, offers a testable model for psychosis. Recent EEG and fMRI data show that brain areas activated during lucid dreaming overlap strikingly with regions impaired in psychotic patients who lack insight into their condition. This parallel suggests that insight into dreaming and insight into psychosis share similar neural correlates, opening new avenues for therapeutic approaches and testing antipsychotic medication.
Sleep Medicine Reviews
April 1, 2013
Gotthard G. Tribl, Thomas C. Wetter, Michael Schredl
Antidepressants consistently reduce how often people recall their dreams, especially tricyclic antidepressants and phenelzine, with a less consistent effect for SSRIs and SNRIs. Tricyclic antidepressants also make dream content more positive, while withdrawing from them or from MAO inhibitors can cause nightmares. In contrast, taking or withdrawing from SSRIs/SNRIs tends to intensify dreaming, which may sometimes lead to nightmares. These findings come from a systematic review of 21 clinical studies and 25 case reports covering 1950 to 2010, involving both depressed patients and healthy volunteers. The authors note that despite clear pharmacological effects, research on this topic has been scarce over the past 60 years.
Sleep Medicine Reviews
May 14, 2011
B. Sharpless, J. Barber
Lifetime prevalence of sleep paralysis varies by population: 7.6% in the general population, 28.3% in students, and 31.9% in psychiatric patients. Among psychiatric patients with panic disorder, 34.6% reported at least one episode. Minorities experience sleep paralysis at higher rates than Caucasians. The authors conclude that sleep paralysis is relatively common and should be assessed more regularly to understand its impact on functioning and its relation to psychiatric and medical conditions.
Sleep Medicine Reviews
April 1, 2011
Michael Schredl, Iris Reinhard
Women tend to report nightmares more often than men, but this gender difference does not appear in children or older persons. A meta-analysis of 111 independent studies found that the difference emerges in adolescence, narrows with increasing age, and is influenced by how nightmare frequency is measured—studies using binary (yes/no) items show a smaller difference than those using rating scales. The definition of nightmare did not affect the gender gap. For children, the most influential factor was whether the data came from children's self-reports or parent reports. Candidate explanations such as dream recall frequency, depression, childhood trauma, and insomnia remain unexamined in systematic research on this gender difference.
Sleep Medicine Reviews
August 1, 2010
Marie Vandekerckhove, Raymond Cluydts
Daytime emotional stress affects sleep physiology, dream patterns, and dream content, though its exact role remains unclear. Observed effects include exaggerated startle response, decreased dream recall, elevated awakening thresholds from REM sleep, altered REM latency, increased REM density and duration, and arousals indicating sleep disruption. Conversely, sleep quality and amount influence reactions to daytime events and general well-being. Sleep appears restorative, while deprivation heightens sensitivity to emotional and stressful stimuli. REM sleep, characterized by hyperlimbic and hypoactive dorsolateral prefrontal functioning alongside normal medial prefrontal cortex activity, is thought to mediate sleep's impact on next-day mood and coping.
Sleep Medicine Reviews
June 1, 2009
Michael Schredl
Dream recall is heightened in people with insomnia, and their dreams reflect current stressors. Breathing-related dreams are rare in sleep apnea patients, while the deregulation of REM sleep in narcolepsy produces more bizarre and negatively toned dreams. These findings support the arousal-retrieval model of dream recall but also indicate that cognitive impairment or micro-arousal may affect dreaming. The content analyses support the continuity hypothesis, which holds that waking-life issues appear in dreams. However, the number of studies is small, and further research is needed.
Sleep Medicine Reviews
February 1, 2006
Victor I. Spoormaker, Michael Schredl, Jan Van den Bout
The DSM-IV-TR definition of nightmares is too narrow, as nightmares can involve emotions other than fear, such as anger or grief, and waking directly from a bad dream does not necessarily increase distress. Measuring nightmare frequency is problematic: polysomnography reduces nightmare frequency, retrospective reports underestimate it, and frequent nightmare sufferers may avoid daily logs. Idiopathic and posttraumatic nightmares differ, with posttraumatic ones linked to more and longer awakenings and both associated with periodic limb movements. Nightmares correlate with neuroticism and general psychopathology, and nightmare distress mediates daily impact. Imagery rehearsal therapy is the preferred cognitive-behavioral treatment, though no randomized controlled trial with an attention control group has been conducted. Nightmares should be treated as a separate, prevalent sleep disorder.