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Neuroscience and Biobehavioral Reviews May 2019Lucid dreaming refers to the phenomenon of becoming aware of the fact that one is dreaming during ongoing sleep. Despite having been physiologically validated for... (Review)
Review
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.
Topics: Awareness; Brain; Brain Mapping; Brain Waves; Cognitive Neuroscience; Dreams; Humans; Magnetic Resonance Imaging; Metacognition; Transcranial Direct Current Stimulation
PubMed: 30880167
DOI: 10.1016/j.neubiorev.2019.03.008 -
Neurotherapeutics : the Journal of the... Jan 2021Nightmare disorder and recurrent isolated sleep paralysis are rapid eye movement (REM) parasomnias that cause significant distress to those who suffer from them.... (Review)
Review
Nightmare disorder and recurrent isolated sleep paralysis are rapid eye movement (REM) parasomnias that cause significant distress to those who suffer from them. Nightmare disorder can cause insomnia due to fear of falling asleep through dread of nightmare occurrence. Hyperarousal and impaired fear extinction are involved in nightmare generation, as well as brain areas involved in emotion regulation. Nightmare disorder is particularly frequent in psychiatric disorders and posttraumatic stress disorder. Nonmedication treatment, in particular imagery rehearsal therapy, is especially effective. Isolated sleep paralysis is experienced at least once by up to 40% of the general population, whereas recurrence is less frequent. Isolated sleep paralysis can be accompanied by very intense and vivid hallucinations. Sleep paralysis represents a dissociated state, with persistence of REM atonia into wakefulness. Variations in circadian rhythm genes might be involved in their pathogenesis. Predisposing factors include sleep deprivation, irregular sleep-wake schedules, and jetlag. The most effective therapy consists of avoiding those factors.
Topics: Dreams; Humans; Sleep Paralysis; Sleep, REM
PubMed: 33230689
DOI: 10.1007/s13311-020-00966-8 -
ELife Jun 2020Deep inside the temporal lobe of the brain, the hippocampus has a central role in our ability to remember, imagine and dream.
Deep inside the temporal lobe of the brain, the hippocampus has a central role in our ability to remember, imagine and dream.
Topics: Brain; Dreams; Hippocampus; Mental Recall
PubMed: 32508304
DOI: 10.7554/eLife.58874 -
Nature Neuroscience Jun 2017Consciousness never fades during waking. However, when awakened from sleep, we sometimes recall dreams and sometimes recall no experiences. Traditionally, dreaming has...
Consciousness never fades during waking. However, when awakened from sleep, we sometimes recall dreams and sometimes recall no experiences. Traditionally, dreaming has been identified with rapid eye-movement (REM) sleep, characterized by wake-like, globally 'activated', high-frequency electroencephalographic activity. However, dreaming also occurs in non-REM (NREM) sleep, characterized by prominent low-frequency activity. This challenges our understanding of the neural correlates of conscious experiences in sleep. Using high-density electroencephalography, we contrasted the presence and absence of dreaming in NREM and REM sleep. In both NREM and REM sleep, reports of dream experience were associated with local decreases in low-frequency activity in posterior cortical regions. High-frequency activity in these regions correlated with specific dream contents. Monitoring this posterior 'hot zone' in real time predicted whether an individual reported dreaming or the absence of dream experiences during NREM sleep, suggesting that it may constitute a core correlate of conscious experiences in sleep.
Topics: Adult; Aged; Cerebral Cortex; Dreams; Electroencephalography; Female; Humans; Male; Mental Recall; Middle Aged; Polysomnography; Sleep Stages; Young Adult
PubMed: 28394322
DOI: 10.1038/nn.4545 -
Journal of Sleep Research Aug 2019This consensus paper provides an overview of the state of the art in research on the aetiology and treatment of nightmare disorder and outlines further perspectives on... (Review)
Review
This consensus paper provides an overview of the state of the art in research on the aetiology and treatment of nightmare disorder and outlines further perspectives on these issues. It presents a definition of nightmares and nightmare disorder followed by epidemiological findings, and then explains existing models of nightmare aetiology in traumatized and non-traumatized individuals. Chronic nightmares develop through the interaction of elevated hyperarousal and impaired fear extinction. This interplay is assumed to be facilitated by trait affect distress elicited by traumatic experiences, early childhood adversity and trait susceptibility, as well as by elevated thought suppression and potentially sleep-disordered breathing. Accordingly, different treatment options for nightmares focus on their meaning, on the chronic repetition of the nightmare or on maladaptive beliefs. Clinically, knowledge of healthcare providers about nightmare disorder and the delivery of evidence-based interventions in the healthcare system is discussed. Based on these findings, we highlight some future perspectives and potential further developments of nightmare treatments and research into nightmare aetiology.
Topics: Child; Dreams; Female; Humans; Imagery, Psychotherapy; Male
PubMed: 30697860
DOI: 10.1111/jsr.12820 -
JAMA Jul 2021Cytisine is more effective than placebo and nicotine replacement therapy for smoking cessation. However, cytisine has not been tested against the most effective smoking... (Comparative Study)
Comparative Study Randomized Controlled Trial
IMPORTANCE
Cytisine is more effective than placebo and nicotine replacement therapy for smoking cessation. However, cytisine has not been tested against the most effective smoking cessation medication, varenicline, which is associated with adverse events known to lead to discontinuation of therapy.
OBJECTIVE
To examine whether standard cytisine treatment (25 days) was at least as effective as standard varenicline treatment (84 days) for smoking cessation.
DESIGN, SETTING, AND PARTICIPANTS
This noninferiority, open-label randomized clinical trial with allocation concealment and blinded outcome assessment was undertaken in Australia from November 2017 through May 2019; follow-up was completed in January 2020. A total of 1452 Australian adult daily smokers willing to make a quit attempt were included. Data collection was conducted primarily by computer-assisted telephone interview, but there was an in-person visit to validate the primary outcome.
INTERVENTIONS
Treatments were provided in accordance with the manufacturers' recommended dosage: cytisine (n = 725), 1.5-mg capsules taken 6 times daily initially then gradually reduced over the 25-day course; varenicline (n = 727), 0.5-mg tablets titrated to 1 mg twice daily for 84 days (12 weeks). All participants were offered referral to standard telephone behavioral support.
MAIN OUTCOMES AND MEASURES
The primary outcome was 6-month continuous abstinence verified using a carbon monoxide breath test at 7-month follow-up. The noninferiority margin was set at 5% and the 1-sided significance threshold was set at .025.
RESULTS
Among 1452 participants who were randomized (mean [SD] age, 42.9 [12.7] years; 742 [51.1%] women), 1108 (76.3%) completed the trial. Verified 6-month continuous abstinence rates were 11.7% for the cytisine group and 13.3% for the varenicline group (risk difference, -1.62% [1-sided 97.5% CI, -5.02% to ∞]; P = .03 for noninferiority). Self-reported adverse events occurred less frequently in the cytisine group (997 events among 482 participants) compared with the varenicline group (1206 events among 510 participants) and the incident rate ratio was 0.88 (95% CI, 0.81 to 0.95; P = .002).
CONCLUSIONS AND RELEVANCE
Among daily smokers willing to quit, cytisine treatment for 25 days, compared with varenicline treatment for 84 days, failed to demonstrate noninferiority regarding smoking cessation.
TRIAL REGISTRATION
anzctr.org.au Identifier: ACTRN12616001654448.
Topics: Adult; Alkaloids; Azocines; Dreams; Female; Humans; Male; Middle Aged; Nausea; Quinolizines; Smoking Cessation; Smoking Cessation Agents; Treatment Outcome; Varenicline
PubMed: 34228066
DOI: 10.1001/jama.2021.7621 -
Neuroscience of Consciousness 2017Nightly transitions into sleep are usually uneventful and transpire in the blink of an eye. But in the laboratory these transitions afford a unique view of how... (Review)
Review
Nightly transitions into sleep are usually uneventful and transpire in the blink of an eye. But in the laboratory these transitions afford a unique view of how experience is transformed from the perceptually grounded consciousness of wakefulness to the hallucinatory simulations of dreaming. The present review considers imagery in the sleep-onset transition-"microdreams" in particular-as an alternative object of study to dreaming as traditionally studied in the sleep lab. A focus on microdream phenomenology has thus far proven fruitful in preliminary efforts to (i) develop a classification for dreaming's core phenomenology (the "oneiragogic spectrum"), (ii) establish a structure for assessing dreaming's multiple memory inputs ("multi-temporal memory sources"), (iii) further Silberer's project for classifying sleep-onset images in relation to waking cognition by revealing two new imagery types ("autosensory imagery," "exosensory imagery"), and (iv) embed a potential understanding of microdreaming processes in a larger explanatory framework ("multisensory integration approach"). Such efforts may help resolve outstanding questions about dream neurophysiology and dreaming's role in memory consolidation during sleep but may also advance discovery in the neuroscience of consciousness more broadly.
PubMed: 30042836
DOI: 10.1093/nc/nix001 -
Somnologie : Schlafforschung Und... 2022The pandemic caused by the coronavirus disease 2019 (COVID-19) had a huge impact on public mental health. This was also reflected in dreams. Not only did people start... (Review)
Review
The pandemic caused by the coronavirus disease 2019 (COVID-19) had a huge impact on public mental health. This was also reflected in dreams. Not only did people start to remember more dreams, but dream content changed as themes like sickness, confinement, and-in the English-speaking world-even bugs began to dominate. This also led to an increase in nightmare frequency. There are various factors that contributed to this change in the dream landscape. Some people have started to sleep more and hereby spend more time in REM sleep, which is known to increase dream recall and further lead to bizarre and vivid dreams. On the other hand, stress and poor mental health had an impact on sleep, and sleep quality thus dropped in many individuals. Poor sleep quality can also lead to an increase in dream recall. Dreams are known to regulate mood, so the rise in dreams and the change in dream content could also reflect a reaction to the overall rise in stress and decline in mental health. Recent studies have shown that as the pandemic progresses, further changes in mental health, dream recall, and dream content arise, but data are still scarce. Further research could help understand the impact the pandemic still has on mental health and dreams, and how this impact is changing over the course of the pandemic.
PubMed: 35528045
DOI: 10.1007/s11818-022-00351-x -
The New England Journal of Medicine Feb 2018In randomized trials, prazosin, an α-adrenoreceptor antagonist, has been effective in alleviating nightmares associated with post-traumatic stress disorder (PTSD) in... (Randomized Controlled Trial)
Randomized Controlled Trial
BACKGROUND
In randomized trials, prazosin, an α-adrenoreceptor antagonist, has been effective in alleviating nightmares associated with post-traumatic stress disorder (PTSD) in military veterans.
METHODS
We recruited veterans from 13 Department of Veterans Affairs medical centers who had chronic PTSD and reported frequent nightmares. Participants were randomly assigned to receive prazosin or placebo for 26 weeks; the drug or placebo was administered in escalating divided doses over the course of 5 weeks to a daily maximum of 20 mg in men and 12 mg in women. After week 10, participants continued to receive prazosin or placebo in a double-blind fashion for an additional 16 weeks. The three primary outcome measures were the change in score from baseline to 10 weeks on the Clinician-Administered PTSD Scale (CAPS) item B2 ("recurrent distressing dreams"; scores range from 0 to 8, with higher scores indicating more frequent and more distressing dreams); the change in score from baseline to 10 weeks on the Pittsburgh Sleep Quality Index (PSQI; scores range from 0 to 21, with higher scores indicating worse sleep quality); and the Clinical Global Impression of Change (CGIC) score at 10 weeks (scores range from 1 to 7, with lower scores indicating greater improvement and a score of 4 indicating no change).
RESULTS
A total of 304 participants underwent randomization; 152 were assigned to prazosin, and 152 to placebo. At 10 weeks, there were no significant differences between the prazosin group and the placebo group in the mean change from baseline in the CAPS item B2 score (between-group difference, 0.2; 95% confidence interval [CI], -0.3 to 0.8; P=0.38), in the mean change in PSQI score (between-group difference, 0.1; 95% CI, -0.9 to 1.1; P=0.80), or in the CGIC score (between-group difference, 0; 95% CI, -0.3 to 0.3; P=0.96). There were no significant differences in these measures at 26 weeks (a secondary outcome) or in other secondary outcomes. At 10 weeks, the mean difference between the prazosin group and the placebo group in the change from baseline in supine systolic blood pressure was a decrease of 6.7 mm Hg. The adverse event of new or worsening suicidal ideation occurred in 8% of the participants assigned to prazosin versus 15% of those assigned to placebo.
CONCLUSIONS
In this trial involving military veterans who had chronic PTSD, prazosin did not alleviate distressing dreams or improve sleep quality. (Funded by the Department of Veterans Affairs Cooperative Studies Program; PACT ClinicalTrials.gov number, NCT00532493 .).
Topics: Adrenergic alpha-1 Receptor Antagonists; Adult; Combined Modality Therapy; Dose-Response Relationship, Drug; Double-Blind Method; Dreams; Female; Hospitals, Veterans; Humans; Male; Middle Aged; Prazosin; Psychiatric Status Rating Scales; Psychotherapy; Sleep; Sleep Wake Disorders; Stress Disorders, Post-Traumatic; Suicidal Ideation; Treatment Failure; United States; Veterans
PubMed: 29414272
DOI: 10.1056/NEJMoa1507598 -
The Journal of Comparative Neurology Dec 2020The presence of dreams in human sleep, especially in REM sleep, and the detection of physiologically similar states in mammals has led many to ponder whether animals... (Review)
Review
The presence of dreams in human sleep, especially in REM sleep, and the detection of physiologically similar states in mammals has led many to ponder whether animals experience similar sleep mentation. Recent advances in our understanding of the anatomical and physiological correlates of sleep stages, and thus dreaming, allow a better understanding of the possibility of dream mentation in nonhuman mammals. Here, we explore the potential for dream mentation, in both non-REM and REM sleep across mammals. If we take a hard-stance, that dream mentation only occurs during REM sleep, we conclude that it is unlikely that monotremes, cetaceans, and otariid seals while at sea, have the potential to experience dream mentation. Atypical REM sleep in other species, such as African elephants and Arabian oryx, may alter their potential to experience REM dream mentation. Alternatively, evidence that dream mentation occurs during both non-REM and REM sleep, indicates that all mammals have the potential to experience dream mentation. This non-REM dream mentation may be different in the species where non-REM is atypical, such as during unihemispheric sleep in aquatic mammals (cetaceans, sirens, and Otariid seals). In both scenarios, the cetaceans are the least likely mammalian group to experience vivid dream mentation due to the morphophysiological independence of their cerebral hemispheres. The application of techniques revealing dream mentation in humans to other mammals, specifically those that exhibit unusual sleep states, may lead to advances in our understanding of the neural underpinnings of dreams and conscious experiences.
Topics: Animals; Dreams; Electroencephalography; Humans; Sleep Stages
PubMed: 31960424
DOI: 10.1002/cne.24860