Lifetime prevalence rates of sleep paralysis: a systematic review

Dosing Optimization of Low-Sodium Oxybate in Narcolepsy and Idiopathic Hypersomnia in Adults: Consensus Recommendations

INTRODUCTION

Low-sodium oxybate (LXB) is approved for treatment of narcolepsy in patients aged 7 years and older and treatment of idiopathic hypersomnia in adults. LXB contains the same active moiety with 92% less sodium than sodium oxybate (SXB). As the indication for oxybate treatment in patients with idiopathic hypersomnia is new and allows for individualized dosing optimization, guidance for beginning LXB treatment is needed. In particular, clinicians may benefit from guidance regarding treatment initiation, dosing/regimen options, potential challenges, and treatment expectations. Additionally, pharmacokinetic profiles differ slightly between both treatments, and further guidance on transitioning from SXB to LXB in patients with narcolepsy may aid clinicians.

METHODS

An expert panel of five sleep specialists was convened to obtain consensus on recommendations for these topics using a modified Delphi process.

RESULTS

Across two virtual meetings, the panel agreed on 31 recommendations with a high degree of consensus that fell into four overarching topics: (1) introducing LXB to patients; (2) initiating LXB for adult narcolepsy and idiopathic hypersomnia; (3) addressing challenges in using LXB; and (4) transitioning from SXB to LXB. The panel recommended that clinicians provide a clear overview of how LXB works for treating symptoms in narcolepsy or idiopathic hypersomnia, as appropriate for their patients, explain safety aspects, and set expectations prior to initiating LXB treatment. Strategies for initial dosing and regimen are provided. Strategies for adjusting the dose, regimen, timing, and consideration of individual factors were developed for specific instances in which patients may have trouble staying asleep or waking up, as well as guidance for addressing potential adverse events, such as nausea, dizziness, anxiety, and depression. Discussion points based on existing literature and clinical experience were included as relevant for each statement.

CONCLUSION

Clinicians may use this resource to guide LXB dosing optimization with patients.

Making sense of narcolepsy: A qualitative exploration of how persons with narcolepsy perceive symptoms and their illness experience

INTRODUCTION

Understanding how persons with narcolepsy conceptualize symptoms, daily impact and illness experience is key to facilitating dialogue between patients and healthcare professionals. These concepts are usually explored from the perspective of healthcare professionals/researchers and rarely from the perspective of those with narcolepsy.

METHODS

127 self-reported persons with narcolepsy were recruited from an Australian patient support group. A short demographic survey was completed. All agreed to participate in a subsequent 1:1 semi-structured interview. Saturation was reached after 24 interviews (mean age = 33 years (SD 11) with 44% reporting cataplexy). A multidisciplinary team of researchers/clinicians analyzed interview transcripts using thematic analysis.

RESULTS

Participants perceived physical fatigue, sleepiness, and two separate experiences of 'falling asleep/sleep attacks' as distinct symptoms rather than a multidimensional construct (i.e. excessive daytime sleepiness). We also identified two experiences of cataplexy, one triggered by acute emotion and another by a stressor. Participants determined their narcolepsy to be 'well-managed' by the level of functional impairment rather than the frequency of any symptom. Almost all participants described experiencing anticipated stigma and internalized or 'self-' stigma, likely stemming from societal devaluation of sleep and the conflation of sleepiness with laziness.

CONCLUSION

Descriptions of common symptoms often differed between participants and the existing literature. These differences likely impact patient-physician communication, with both parties utilizing the same terminology to communicate different concepts. The characterization of stigma in narcolepsy presents opportunities for future research exploring the impact and possible development of interventions to reduce the substantial psychological comorbidity in persons with narcolepsy.

Recurrent Isolated Sleep Paralysis

Recurrent isolated sleep paralysis has a 7.6% lifetime prevalence of at least one episode in the general population. Episodes resolve spontaneously and are benign. Sleep paralysis represents a dissociate state, with persistence of the rapid eye movement (REM)-sleep muscle atonia in the waking state. The intrusion of alpha electroencephalogram into REM sleep is followed by an arousal response and then by persistence of REM atonia into wakefulness. Predisposing factors include irregular sleep-wake schedules, sleep deprivation, and jetlag. No drug treatment is required. Patients should be informed about sleep hygiene. Cognitive behavioral therapy may be useful in cases accompanied by anxiety and frightening hallucinations.

The Parasomnias

Parasomnias usually present in childhood and resolve spontaneously. The diagnosis of non-rapid eye movement-related parasomnias is mainly based on clinical descriptors and can be challenging. Rapid eye movement-related parasomnias may index an underlying psychiatric disorder. Even if benign, parasomnias can affect quality of life. Pediatricians and child psychiatrists should be familiarized with these sleep disorders and suggest adequate sleep hygiene, avoidance of sleep deprivation, and regular bedtimes even on weekends as the first step in management of these disorders. Clinicians should pursue the opportunity for tailoring treatments and consider referral to a sleep expert when indicated.

All-night spectral and microstate EEG analysis in patients with recurrent isolated sleep paralysis

The pathophysiology of recurrent isolated sleep paralysis (RISP) has yet to be fully clarified. Very little research has been performed on electroencephalographic (EEG) signatures outside RISP episodes. This study aimed to investigate whether sleep is disturbed even without the occurrence of a RISP episode and in a stage different than conventional REM sleep. 17 RISP patients and 17 control subjects underwent two consecutive full-night video-polysomnography recordings. Spectral analysis was performed on all sleep stages in the delta, theta, and alpha band. EEG microstate (MS) analysis was performed on the NREM 3 phase due to the overall high correlation of subject template maps with canonical templates. Spectral analysis showed a significantly higher power of theta band activity in REM and NREM 2 sleep stages in RISP patients. The observed rise was also apparent in other sleep stages. Conversely, alpha power showed a downward trend in RISP patients' deep sleep. MS maps similar to canonical topographies were obtained indicating the preservation of prototypical EEG generators in RISP patients. RISP patients showed significant differences in the temporal dynamics of MS, expressed by different transitions between MS C and D and between MS A and B. Both spectral analysis and MS characteristics showed abnormalities in the sleep of non-episodic RISP subjects. Our findings suggest that in order to understand the neurobiological background of RISP, there is a need to extend the analyzes beyond REM-related processes and highlight the value of EEG microstate dynamics as promising functional biomarkers of RISP.

To be or not to be hallucinating: Implications of hypnagogic/hypnopompic experiences and lucid dreaming for brain disorders

The boundaries between waking and sleeping-when falling asleep (hypnagogic) or waking up (hypnopompic)-can be challenging for our ability to monitor and interpret reality. Without proper understanding, bizarre but relatively normal hypnagogic/hypnopompic experiences can be misinterpreted as psychotic hallucinations (occurring, by definition, in the fully awake state), potentially leading to stigma and misdiagnosis in clinical contexts and to misconception and bias in research contexts. This Perspective proposes that conceptual and practical understanding for differentiating hallucinations from hypnagogic/hypnopompic experiences may be offered by lucid dreaming, the state in which one is aware of dreaming while sleeping. I first introduce a possible systematization of the phenomenological range of hypnagogic/hypnopompic experiences that can occur in the transition from awake to REM dreaming (including hypnagogic perceptions, transition symptoms, sleep paralysis, false awakenings, and out-of-body experiences). I then outline how metacognitive strategies used by lucid dreamers to gain/confirm oneiric lucidity could be tested for better differentiating hypnagogic/hypnopompic experiences from hallucinations. The relevance of hypnagogic/hypnopompic experiences and lucid dreaming is analyzed for schizophrenia and narcolepsy, and discussed for neurodegenerative diseases, particularly Lewy-body disorders (i.e. Parkinson's disease, Parkinson's disease dementia, and dementia with Lewy bodies), offering testable hypotheses for empirical investigation. Finally, emotionally positive lucid dreams triggered or enhanced by training/induction strategies or by a pathological process may have intrinsic therapeutic value if properly recognized and guided. The overall intention is to raise awareness and foster further research about the possible diagnostic, prognostic, and therapeutic implications of hypnagogic/hypnopompic experiences and lucid dreaming for brain disorders.

Prevalence and Clinical Characteristics of Sleeping Paralysis: A Systematic Review and Meta-Analysis

Sleep paralysis (SP) is a mixed state of consciousness and sleep, combining features of rapid eye movement (REM) sleep with those of wakefulness. The exact cause of SP is unknown, and its prevalence varies among the studies. We aim to identify SP's global prevalence, the affected population's characteristics, and the SP's clinical picture. We searched three databases (PubMed, Scopus, and Web of Science (WoS)) using a unique search strategy to identify eligible studies. All observational studies identifying the prevalence or frequency of sleeping paralysis were included. No exclusions are made based on country, race, or questionnaire. The analysis was performed using the latest version of R software (R Core Team, Vienna, Austria). The analysis included 76 studies from 25 countries with 167,133 participants. The global prevalence of SP was 30% (95% CI (22%, 39%)). There were similar frequencies of isolated SP and SP (33%, 95% CI (26%, 42%), I2 = 97%, P <0.01; 31%, 95% CI (21%, 43%), I2 = 100%, P = 0, respectively). A subgroup analysis showed that the majority of those who experienced SP were psychiatric patients (35%, 95% CI (20%, 55%), I2 = 96%, P <0.01). The prevalence among non-psychiatric patients was among students (34%, 95% CI (23%, 47%), I2 = 100%, P = 0). Auditory and visual hallucinations were reported in 24.25% of patients. Around 4% had only visual hallucinations. Meta-regression showed no association between the frequency of SP and sex. Publication bias was detected among the included studies through visual inspection of funnel plot asymmetry. Our findings revealed that 30% of the population suffered from SP, especially psychiatric patients and students. The majority of SP cases lacked associated hallucinations, while a noteworthy proportion experienced combined visual and auditory hallucinations.

Frequency and Factors of Sleep Paralysis Among Medical Students of Karachi

INTRODUCTION

Sleep paralysis is a prevalent phenomenon characterized by suffocation, immobility, and hallucinations. Its causes remain unknown, although the neurotransmitter imbalance is suggested as a potential factor. This condition is closely associated with hallucinations and a sense of intrusion, often observed in patients with narcolepsy, hypertension, and seizures.

METHODS

A cross-sectional study was conducted in various medical colleges in Karachi, involving 297 participants aged 18 to 30 years. The participants were divided into groups based on gender and year of study. They were surveyed about the frequency of sleep paralysis episodes, their beliefs about the phenomenon, sleep routines, and academic impacts.

RESULTS

Among the respondents, a significant number of females (n=209, 70.3%) reported experiencing sleep paralysis. The overall mean age was 20±2.0 years. Correlation analysis revealed an insignificant relationship between depression and mental anxiety (p=0.147). Similarly, no significant association was found when comparing the occurrence of sleep paralysis (p=0.16). However, a notable finding was the significant link between sleep paralysis and its impact on academics (p=0.043).

CONCLUSION

This study highlighted the frequency of sleep paralysis among medical students, particularly among females. Furthermore, it emphasizes the diverse beliefs held by individuals regarding these frightening episodes. To address this neglected issue, it is essential to conduct awareness sessions aimed at understanding and alleviating sleep paralysis in individuals' lives.

Narcolepsy and Idiopathic Hypersomnia

Narcolepsy types 1 and 2 and idiopathic hypersomnia are primary Central Nervous System (CNS) disorders of hypersomnolence characterized by profound daytime sleepiness and/or excessive sleep need. Onset of symptoms begins typically in childhood or adolescence, and children can have unique presentations compared with adults. Narcolepsy type 1 is likely caused by immune-mediated loss of orexin (hypocretin) neurons in the hypothalamus; however, the causes of narcolepsy type 2 and idiopathic hypersomnia are unknown. Existing treatments improve daytime sleepiness and cataplexy but there is no cure for these disorders.

The prevalence of sleep paralysis in medical students in Buenos Aires, Argentina

Objectives

The objectives of this study were to determine the prevalence of sleep paralysis (SP) in medical students from the University of Buenos Aires (UBA).

Materials and Methods

An ad hoc questionnaire based on the diagnosis of SP and a demographic survey was electronically presented to students of Internal Medicine at the School of Medicine of the UBA. The respondents answered both questionnaires using Google Forms®.

Results

The prevalence of SP was 40.7% (95% CI 33.5-47.8). A higher percentage of the respondents (76%) reported experiencing SP-related anxiety. An association between self-perceived quality of sleep and the incidence of SP was found (χ2: 12.712, P = 0.002). The highest frequency was hypnopompic SP (55.55%), and the highest percentage (55.4%) suffered from SP less than once every 6 months. Most respondents (59.5%) reported having started with SP symptoms after 18 years of age, and the highest percentage (66.2%) had exacerbated their symptoms at college. The frequency of the Incubus phenomenon was 14.5% (95% CI 6.2-23). Most respondents (70.8%) denied the association of SP with religious or paranormal beliefs.

Conclusion

SP is highly prevalent in medical students and is associated with poor sleep habits and perceived poor sleep quality. Clinicians should be aware of this parasomnia to avoid a misdiagnosis of psychosis and inform sufferers of the nature of SP.

Isolated sleep paralysis: Clinical features, perception of aetiology, prevention and disruption strategies in a large international sample

STUDY OBJECTIVES

Isolated sleep paralysis is a benign but frightening condition characterised by a temporary inability to move at sleep onset or upon awakening. Despite the prevalence of this condition, little is known concerning its clinical features, associated demographic characteristics, and prevention as well as disruption strategies.

METHODS

An online cross-sectional study was conducted. The sample comprised 3523 participants who had reported at least one lifetime episode of ISP and 3288 participants without a lifetime episode. Participants answered a survey including questions about sleep quality, sleep paralysis, and sleep paralysis prevention/disruption techniques.

RESULTS

A total of 6811 participants were investigated (mean age = 46.9, SD = 15.4, age range = 18-89, 66.1% female). Those who reported experiencing ISP at least once during their lives reported longer sleep onset latencies, shorter sleep duration, and greater insomnia symptoms. Females (vs. male) and younger (vs. older) participants were more likely to experience ISP. Significant fear during episodes was reported by 76.0% of the participants. Most people (63.3%) who experienced ISP believed it to be caused by 'something in the brain'. A minority endorsed supernatural causes (7.1%). Five prevention strategies (e.g., changing sleep position, adjusting sleep patterns) with at least 60.0% effectiveness, and five disruption strategies (e.g., physical/bodily action, making noise) with varying degrees of effectiveness (ranging from 29.5 to 61.8) were identified through open-ended responses.

CONCLUSIONS

ISP is associated with shorter sleep duration, longer sleep onset latency, and greater insomnia symptoms. The multiple prevention and disruption techniques identified in this study support existing treatment approaches and may inform subsequent treatment development. Implications for current diagnostic criteria are discussed.

Recurrent fearful isolated sleep paralysis - A distressing co-morbid condition of obstructive sleep apnea

We present a case of recurrent fearful isolated sleep paralysis in a 52-year-old male of Indo-Caribbean ethnicity with obstructive sleep apnea (OSA). Recurrent sleep paralysis is a widely under-reported yet worrisome symptom of various sleep disorders. Although a benign condition in most cases, sleep paralysis in a minority of patients causes great distress. Some patients exhibit bedroom avoidance behavior, whereas others experience bedtime anxiety, making it difficult to fall asleep. This leads to poor sleep quality and sleep deprivation, which can greatly impact a person's overall health. As in our case, this led to a vicious "lack of sleep" cycle where a patient who had bedtime anxiety and could not fall asleep, owing to his recurrent isolated sleep paralysis, also had poor quality sleep secondary to his OSA. This increases morbidity and has many potential consequences, which may include cardiovascular events, cognitive decline, and motor vehicular accidents. Sometimes, simply addressing the underlying medical condition cures the recurrent sleep paralysis as in this case where continuous positive airway pressure for OSA cured the recurrent sleep paralysis. One of our goals is to raise awareness of recurrent sleep paralysis so that patients can seek medical help and would not have to live with the anguish of the condition. Coming forward will also assist medical researchers in furthering their understanding of sleep paralysis.

Clinical considerations for the diagnosis of idiopathic hypersomnia

Idiopathic hypersomnia is a sleep disorder of neurologic origin characterized by excessive daytime sleepiness, with sleep inertia, long, unrefreshing naps, and prolonged nighttime sleep being key symptoms in many patients. Idiopathic hypersomnia is described in the International Classification of Sleep Disorders, 3rd Edition as a central disorder of hypersomnolence with distinct clinical features and diagnostic criteria; however, confirming the diagnosis of idiopathic hypersomnia is often challenging. Diagnosis of idiopathic hypersomnia is based on objective sleep testing and the presence of associated clinical features but may be difficult for clinicians to recognize and correctly diagnose because of its low prevalence, clinical heterogeneity, and symptoms, which are similar to those of other sleep disorders. The testing required for diagnosis of idiopathic hypersomnia also presents logistical barriers, and reliability of objective sleep measures is suboptimal. The pathophysiology of idiopathic hypersomnia remains unknown. In this review, clinical considerations related to the pathogenesis, diagnosis, and management of idiopathic hypersomnia will be discussed, including perspectives from the European Union and United States.

Sleep Habits in Pairs of Japanese High School Students and Their Mothers in Summer and Autumn

This study aimed to examine the sleep habits in pairs of Japanese high school students and their mothers in the summer and autumn. Nineteen pairs of high school students and their mothers participated in this study. Wrist actigraphy, subjective sleep evaluations, and bedroom environmental measurements (temperature, humidity, and light) were performed for a duration of one week. The results of a split-plot analysis of variance revealed no significant difference in the actigraphically evaluated time spent in bed (TIB) between the seasons and between the mothers and students. The TIB was approximately 6 h on weekdays, and significantly lengthened to approximately 7 h on weekends (p < 0.05). The average sleep efficiency values recorded were higher than 90%. The mothers showed significantly advanced sleep phases compared to those of the students (p < 0.05). In addition, the waking time on Monday morning was significantly correlated between the mothers and students in the summer and autumn (p < 0.05). A perceived sleep loss “almost every day” or “several times per week” was reported by approximately half of the mothers and students in each season. The students occasionally fell into nocturnal sleep with the room light turned on. These results suggest that sleep hygiene education considering life habit characteristics is required to ensure sufficient sleep time.

Successful treatment of sleep paralysis with the Sleep Position Trainer: a case report

Sleep paralysis is a period of paralysis at either sleep onset or upon awakening and is often accompanied by terrifying hallucinations. We report a case of a 32-year-old healthy men with a history of mild positional obstructive sleep apnea and sleep paralysis. The positional sleep apnea was successfully treated with the Sleep Position Trainer. Remarkably, he did no longer experience episodes of sleep paralysis since using the Sleep Position Trainer. This case highlights a possible elegant noninvasive long-term solution for the treatment of sleep paralysis.

CITATION

Cui N, van Looij MA, Kasius KM. Successful treatment of sleep paralysis with the Sleep Position Trainer: a case report. J Clin Sleep Med. 2022;18(9):2317-2319.

Sleep paralysis in college students

Objective: We examined the prevalence of sleep paralysis (SP), its association with stress and sleep, and associated subjective experiences and beliefs. Participants: 1,115 college students from a large university in the southwestern United States. The sample was predominantly Hispanic (94%) and female (70%). Methods: Validated measures of life-events stress, self-perceived stress, sleep quality and insomnia were administered to participants online. Results: 35% of students had previously experienced SP and reported greater stress and poorer sleep than those who had never experienced it. Effect sizes were larger when comparing those who had/had not experienced SP within the prior year. Conclusions: Based on our predominantly Hispanic and majority female sample, we found that SP is experienced by approximately one-third of undergraduate students and associated with both higher stress and poorer sleep. We therefore recommend that college health practitioners seek ways to integrate relevant assessment and education into campus health practices.

Characteristics of Sleep Paralysis and Its Association with Anxiety Symptoms, Perceived Stress, PTSD, and Other Variables Related to Lifestyle in Selected High Stress Exposed Professions

Sleep paralysis (SP) is a hypnagogic or hypnopompic state associated with the inability to move while conscious. Recurrent isolated sleep paralysis (RISP) is a type of REM parasomnia. Individuals experiencing anxiety disorders, PTSD, exposure to chronic stress, or shift work are at risk of developing this sleep disorder. This study aimed to assess: (1) the prevalence, frequency, and symptomatology of SP, and (2) the impact of the severity of anxiety symptoms, perceived stress, and lifestyle mode variables on the frequency and severity of SP in four professional groups at high risk of SP (n = 844): nurses and midwives (n = 172), policemen (n = 174), teachers (n = 107), and a group of mixed professions—“other professions” (n = 391). The study used a battery of online questionnaires: the Sociodemographic and Health Status Questionnaire, the SP-EPQ, the PCL -5, the STAI-T, the PSWQ and the PSS-10. The prevalence of SP was the lowest among policemen (15.5%) and the highest in the group of “other professions” (39.4%). The association of SP with symptoms of PTSD and anxiety was confirmed in the group of nurses and “other professions”. Among other factors modulating the incidence and severity of SP were: age, BMI, smoking, alcohol consumption, sleep duration, and perceived stress. This study indicates that there exist links between SP and psychological and lifestyle factors, suggesting a complex etiology for this sleep disorder. Due to the high prevalence of SP in the studied groups of occupations, further research is necessary to develop preventive and therapeutic methods for SP.

Risk factors of sleep paralysis in a population of Polish students

BACKGROUND

Sleep paralysis (SP) is a transitional dissociative state associated with the REM sleep phase that affects approximately 28.3% of the student population during their lifetime. The reasons for the high prevalence of SP in the student population are not entirely clear. Research indicates possible influencing factors such as the intensification of anxiety symptoms, a tendency to worry, the presence of PTSD symptoms, and behavioral factors such as the consumption of psychoactive substances (caffeine, alcohol, nicotine), sleep deprivations and poor sleep hygiene. The study aimed to assess the prevalence of SP and determine the risk factors for the occurrence of SP in the population of Polish students.

METHODS

The study used a battery online consisting of a set of questionnaires 1) a personal questionnaire, 2) the SP-EPQ, 3) the PCL -5, 4) the STAI-T, 5) the PSWQ. The questionnaire was sent via Facebook to 4500 randomly selected students from different universities in Poland. The questionnaire was completed by 2598 students. To unify the participant sample, people over 35 were excluded from the study (45 students). Ultimately, data from 2553 students were analyzed.

RESULTS

A total of 33.14% of individuals experienced at least one episode of SP in their lives. The highest odds ratio for SP was associated with: the presence of three or more health problems (OR: 2.3; p = 0.002), the presence of any mental disorder (OR: 1.77; p = 0.002), including mood disorders (OR: 2.07; p = 0.002), suffering from at least one somatic disease (OR: 1.34; p = 0.002), a high level of anxiety as a constant personality trait (OR: 1.20; p = 0.035) and smoking (OR: 1.48; p = 0.0002), alcohol consumption (OR: 1.52; p < 0.0001), physical activity (OR: 1.31; p = 0.001).

CONCLUSIONS

The results of our research indicate that a large proportion of students experienced isolated sleep paralysis. Mental and somatic health problems and lifestyle factors were found to predispose individuals to this disorder. Due to the numerous risk factors for SP, it is necessary to conduct additional research to confirm the impact of these factors and to investigate the mechanisms of their influence on SP.

Worsening sleep quality across the lifespan and persistent sleep disturbances in persons with opioid use disorder

STUDY OBJECTIVES

Individuals with opioid use disorder (OUD) may experience worsening sleep quality over time, and a subset of individuals may have sleep disturbances that precede opioid use and do not resolve following abstinence. The purpose of the present study was to (1) collect retrospective reports of sleep across the lifespan and (2) identify characteristics associated with persistent sleep disturbance and changes in sleep quality in persons with OUD.

METHODS

Adults with OUD (n = 154) completed a cross-sectional study assessing current and past sleep disturbance, opioid use history, and chronic pain. Repeated-measures analysis of variance was used to examine changes in retrospectively reported sleep quality, and whether changes varied by screening positive for insomnia and/or chronic pain. Multivariate linear regression analyses were used to identify additional correlates of persistent sleep disturbance.

RESULTS

Participants reported that their sleep quality declined over their lifespan. Changes in reported sleep over time varied based on whether the individual screened positive for co-occurring insomnia and/or chronic pain. In regression analyses, female sex (β = 0.16, P = .042), a greater number of treatment episodes (β = 0.20, P = .024), and positive screens for chronic pain (β = 0.19, P = .018) and insomnia (β=0.22, P = .013) were associated with self-reported persistent sleep disturbance. Only a portion of participants who screened positive for sleep disorders had received a formal diagnosis.

CONCLUSIONS

OUD treatment providers should routinely screen for co-occurring sleep disturbance and chronic pain. Interventions that treat co-occurring OUD, sleep disturbance, and chronic pain are needed.

CITATION

Ellis JD, Mayo JL, Gamaldo CE, Finan PH, Huhn AS. Worsening sleep quality across the lifespan and persistent sleep disturbances in persons with opioid use disorder. J Clin Sleep Med. 2022;18(2):587-595.

Comorbid parasomnias in narcolepsy and idiopathic hypersomnia: more REM than NREM parasomnias

STUDY OBJECTIVES

To assess the frequency, determinants and clinical impact of clinical NREM and REM parasomnias in adult patients with narcolepsy type 1 (NT1), narcolepsy type 2 (NT2), and idiopathic hypersomnia (IH) compared to healthy controls.

METHODS

Familial and past and current personal parasomnias were assessed by questionnaire and medical interviews in 710 patients (220 NT1, 199 NT2, and 221 IH) and 595 healthy controls.

RESULTS

Except for sleep-related eating disorder (SRED), current NREM parasomnias were rare in all patient groups and controls. SRED was more frequent in NT1 patients (7.9%, vs. 1.8% in NT2 patients, 2.1% in IH patients and 1% in controls) and associated with disrupted nighttime sleep (odds ratio [OR] = 3.9) and nocturnal eating in full awareness (OR = 6.9) but not with sex. Clinical REM sleep behavior disorder (RBD) was more frequent in NT1 patients (41.4%, half being violent) than in NT2 patients (13.2%) and affected men more often than women (OR = 2.4). It was associated with disrupted nighttime sleep, depressive symptoms and antidepressant use. Frequent (>1/week) nightmares were reported by 39% of patients with NT1, 29% with NT2 and 27.8% with IH (vs. 8.3% in controls) and were associated with depressive symptoms in narcolepsy. No parasomnia (except sleep-related hallucinations) worsened daytime sleepiness.

CONCLUSIONS

In patients with central disorders of hypersomnolence, comorbid NREM parasomnias (except SRED) are rare and do not worsen sleepiness. In contrast, REM parasomnias are prevalent (especially in NT1) and associated with male sex, disrupted nighttime sleep, depressive symptoms and antidepressant use.

A German online survey of people who have experienced sleep paralysis

We present some key findings from an online survey on isolated sleep paralysis. The aim of our study was to get a differentiated picture of the correlation between the frequency of sleep paralysis and several phenomena (symptoms, experiences) as well as factors correlated with these phenomena. We also investigated the role of gender in relation to the experience of sleep paralysis. We used a selected sample of subjects who had had at least one sleep paralysis experience, with a total of 380 subjects. On average, the participants experienced 10-20 sleep paralysis episodes. We found high and expected positive correlations between the frequency of sleep paralysis experiences and the amount of phenomena, emotions, and perceived shapes and forms experienced during sleep paralysis. An increased frequency of sleep paralysis also appears to lead to habituation and de-dramatization in some affected individuals. Interestingly, significant correlations are missing where one would have suspected them based on the previous hypotheses. Neither self-perceived general stress nor poor sleep hygiene appeared to influence the frequency of sleep paralysis. We found highly significant gender differences in some items. Women reported more experienced phenomena and emotions overall, had more frequent sleep paralysis experiences of the intruder and incubus type, and were significantly more likely to perceive concrete forms such as human figures or people they know. They were also more likely than men to report experiencing fearful emotions, especially the fear of going crazy. Most of these findings were based on exploratory questions; they require replication for validation.

Profiles of sleep and depression risk among Caribbean Blacks

Objectives: Sleep problems are associated with a host of psychiatric disorders and have been attributed to race disparities in health and wellness. Studies of sleep and mental health do not typically consider within-group differences among Blacks. Thus, our understanding of how the sleep-mental health relationship among Caribbean Blacks is limited. This study identified sleep profiles among Caribbean-born Blacks who reside in the United States.Design: Latent class analysis and data from the National Survey of American Life Re-interview study were used to identify and compare the associations between 'sleep quality classes,' sociodemographic factors, stress, and depression risk among Caribbean Blacks.Results: Two sleep quality classes were identified - 'good sleep quality' and 'poor sleep quality' - with each class demonstrating a complex pattern of sleep experiences, and illuminating the association between sleep and depression risk.Conclusions: Findings provide insight into the influence of sociodemographic factors and social stressors on the sleep experience of Caribbean Blacks and the importance of considering within-group differences to better understand risk and resilience among Caribbean Blacks living in the United States. Findings also highlight the importance of screening for sleep problems in an effort to reduce the burden of depression experienced by this population.

Sleep Paralysis among Professional Firefighters and a Possible Association with PTSD-Online Survey-Based Study

The prevalence of sleep paralysis (SP) is estimated at approximately 7.6% of the world’s general population. One of the strongest factors in the onset of SP is PTSD, which is often found among professional firefighters. Our study aimed to assess in the professional firefighter population (n = 831) (1) the prevalence of SP, (2) the relationship between SP and PTSD and (3) the relationship between SP and other factors: the severity of the stress felt, individual tendency to feel anxious and worried and lifestyle variables. The incidence of SP in the study group was 8.7%. The high probability of PTSD was found in 15.04% of subjects and its presence was associated with 1.86 times the odds of developing SP [OR = 1.86 (95% CI: 1.04–3.33); p = 0.04]. Officers who experienced at least 1 SP during their lifetime had significantly higher results in the scales: PCL-5, STAI-T, PSWQ. The number of SP episodes was positively correlated with the severity of symptoms measured by the PCL-5, PSS-10, STAI and PSWQ questionnaires. Further research is needed to assess the importance of SP among the firefighter population in the context of mental and somatic health and to specify methods of preventing SP episodes.

Beliefs about sleep paralysis in Turkey: Karabasan attack

The present study examined explanations of sleep paralysis (SP) in Turkey. The participants were 59 college students recruited in İstanbul, Turkey, who had experienced SP at least once in their lifetime. Participants were administered the Sleep Paralysis Experiences and Phenomenology Questionnaire (SP-EPQ) in an interview. When asked whether they had heard of a name for SP, the vast majority (88%) mentioned the "Karabasan"-a spirit-like creature rooted in Turkish folk tradition. Seventeen percent of the participants believed that their SP might have been caused by this supernatural creature. Thirty-seven percent of participants applied various supernatural and religious methods to prevent future SP attacks such as dua (supplicating to God), reciting the Quran, and wearing a musqa (a type of talisman inscribed with Quranic verses). Case studies are presented to illustrate these findings. The Karabasan constitutes a culturally specific, supernatural interpretation of the phenomenology of SP in Turkey.

Sleep paralysis in Italy: Frequency, hallucinatory experiences, and other features

Previous research has found supernatural beliefs about sleep paralysis (SP) to be very prevalent in Italy, with over one third of SP sufferers believing that their SP might have been caused by a supernatural creature known locally as the Pandafeche. The current study further examined features of SP in Italy. All participants had experienced SP at least once in their lifetime. Participants were recruited from the general population (N =  67) in the region of Abruzzo. The Sleep Paralysis Experiences and Phenomenology Questionnaire (SP-EPQ) was orally administered to participants. As hypothesized, we found that Italians from the general population reported high lifetime rates of SP, prolonged duration of immobility during the event, and great fear of the experience (with as many as 42% of SP sufferers fearing that they could die from the experience), all of which were particularly elevated as compared to cultures where there are no such elaborate traditions of SP (e.g., Denmark). In addition, 78% of participants experienced some type of hallucination during their SP. The results we present here suggest that cultural beliefs about SP in Italy (e.g., as being caused by the Pandafeche, as reported elsewhere) potentially can profoundly shape certain aspects of the experience - a type of mind-body interaction.

The Parasomnias

Parasomnias usually present in childhood and resolve spontaneously. The diagnosis of non-rapid eye movement-related parasomnias is mainly based on clinical descriptors and can be challenging. Rapid eye movement-related parasomnias may index an underlying psychiatric disorder. Even if benign, parasomnias can affect quality of life. Pediatricians and child psychiatrists should be familiarized with these sleep disorders and suggest adequate sleep hygiene, avoidance of sleep deprivation, and regular bedtimes even on weekends as the first step in management of these disorders. Clinicians should pursue the opportunity for tailoring treatments and consider referral to a sleep expert when indicated.

Meditation-Relaxation (MR Therapy) for Sleep Paralysis: A Pilot Study in Patients With Narcolepsy

Sleep paralysis (SP) is a condition where a person is paralyzed upon waking or falling asleep. SP afflicts ~20% of people, and is also one of the typical symptoms in narcolepsy. During SP the sleeper may experience hallucinations. Unsurprisingly, SP is associated with great fear globally. To date, there are no published clinical trials or outcome data for treating this condition. However, few non-pharmacological interventions have been proposed, including cognitive behavioral approaches, and case studies showing clinical amelioration with auto-hypnosis and Meditation-Relaxation (MR) therapy. The latter for instance showed positive preliminary results; when applied for 8 weeks it reduced SP frequency and anxiety/worry symptoms. With this paper we aimed to evaluate, with a small-scale pilot study, the efficacy of MR therapy for SP in patients with narcolepsy. Ten patients with narcolepsy and SP were enrolled in the study. Notably, MR therapy (n = 6), applied for 8 weeks, resulted in a dramatic decrease in the number of days SP occurred (50% reduction); and the total number of SP episodes (54% reduction) in the last month of the study (demonstrated by large within-group effect sizes); unlike the control intervention (deep breathing) (n = 4). These findings are preliminary and exploratory given the small sample. Nonetheless, they represent the first proof of concept at providing empirically-guided insights into the possible efficacy of a novel treatment for frequently occurring SP. Although the study was conducted in patients with narcolepsy we cautiously suggest that the findings may generalize to individuals with isolated SP.

Is there a relation among REM sleep dissociated phenomena, like lucid dreaming, sleep paralysis, out-of-body experiences, and false awakening?

During REM sleep we normally experience dreams. However, there are other less common REM sleep phenomena, like lucid dreaming (LD), false awakening (FA), sleep paralysis (SP), and out of body experiences (OBE). LD occurs when one is conscious during dreaming, and FA occurs when one is dreaming but believes that has woken up. SP is characterized by skeletal muscle atonia and occurs mainly during awakening or falling asleep. OBE is the subjective sensation of 'leaving the physical body'. Since all these phenomena happen during REM sleep, their frequency is probably connected. The goal of this research is to explore how these phenomena are connected to each other in terms of frequency. We surveyed 974 people on the streets of Moscow and found significant correlations between the phenomena. Of those surveyed, 88% have experienced at least one of the phenomena of interest (i.e., LD, OBE, FA, and SP), which appeared to be closely correlated to each other. Furthermore, 43% of respondents stated that they often experience at least one of these phenomena. We found that the recurrence of these phenomena correlated with sleep duration and dream recall frequency. The results of the survey provide better understanding of the nature of REM sleep dissociative phenomena. Cross-correlations between REM sleep dissociated phenomena, like lucid dreaming, sleep paralysis, out-of-body experiences, and false awakening, revealed by a survey.

Prevalence and Clinical Picture of Sleep Paralysis in a Polish Student Sample

Sleep paralysis (SP) is a psychobiological phenomenon caused by temporary desynchrony in the architecture of rapid eye movement (REM) sleep. It affects approximately 7.6% of the general population during their lifetime. The aim of this study was to assess (1) the prevalence of SP among Polish students in Lublin (n = 439) using self-reported online surveys, (2) the frequency of SP-related somatic and psychopathologic symptoms, and (3) the factors potentially affecting the occurrence of symptoms among people experiencing SP. We found that the incidence of SP in the Polish student population was slightly higher (32%) than the average prevalence found in other student populations (28.3%). The SP clinical picture was dominated by somatic symptomatology: 94% of respondents reported somatic symptoms (most commonly tachycardia, 76%), 93% reported fear (most commonly fear of death, 46%), and 66% reported hallucinations (most commonly visual hallucinations, 37%). The number of SP episodes was related to sleep duration and supine position during sleep. The severity of somatic symptoms correlated with lifestyle variables and anxiety symptomatology. Our study shows that a significant proportion of students experience recurrent SP and that this phenomenon is associated with fear and physical discomfort. The scale of the phenomenon requires a deeper analysis.

Abnormal things happening during sleep: parasomnias

Parasomnias are characterized by abnormal experiences, dreams, movements and behavior during sleep. They may occur in the middle of the sleep during REM (rapid eye movement) or NREM (non-rapid eye movement), during falling asleep or waking up. Characteristically for REM behavior disorder is an increased muscle tone although usually REM is defined by an absence of muscle tone. For these forms aggressive dreams may lead to violating bed partners or self-injury of the sleeping person. Even killing bed partners has been described. Many of the patients develop a kind of Parkinson's disease (synucleinopathies). The rate of phenoconversion is more than 30% in 5 years and nearly 100% after 15 years. There are several recommendations regarding a safe sleeping environment. Medicinal treatment consists of either melatonin or clonazepam.

Sleep-Related Practices, Behaviors, and Sleep-Related Difficulties in Deployed Active-Duty Service Members Performing Security Duties

Objective: To assess sleep-related difficulties (e.g., trouble staying asleep, oversleeping, falling asleep while on duty, disturbing dreams, sleep paralysis) and behavioral patterns of active-duty service members (ADSMs) performing security duties. Participants: The participants were 1,169 ADSMs (20-44 years of age). Methods: ADSMs completed an online survey (67.3% response rate) with items assessing demographics, the occupational environment, sleep-related attributes, habits, or difficulties, factors affecting sleep, aids and techniques used to improve sleep, and the use of sleep-related products. Results: ADSMs reported sleeping ~6.5 hr/day (~56% reported sleeping < 6 hr). Sleep-related difficulties were reported by ~72% of the ADSMs (i.e., 55.1% had problems staying asleep, 33.1% reported experiencing sleep paralysis, 25.6% reported oversleeping, 21.6% had disturbing dreams, and 4.79% reported falling asleep while on duty). Daily sleep duration and quality, occupational factors (shift work, operational commitments, collateral duties, habitability, taking antimalarial medication, years deployed), and personal factors or behaviors (history of sleep problems, problems in personal life, late exercise times, altering sleep schedule to talk or text with family or friends) were associated with sleep-related difficulties. Some ADSMs reported using alcohol (~14%) or exercising prior to bedtime (~34%) in an attempt to fall sleep faster. Conclusions: We identified a high prevalence of sleep-related difficulties in our military sample. Even though most ADSMs used sleep hygiene practices to improve their sleep, some ADSMs used methods not recommended. Improving ADSMs' daily schedule (to include periods for exercising, and protected sleep periods), and further emphasis on sleep hygiene practices may be viable methods to reinforce behaviors promoting healthy sleep and improve performance.

Sleepwalking and Sleep Paralysis: Prevalence in Colombian Families With Genetic Generalized Epilepsy

BACKGROUND

Sleep deprivation commonly increases seizure frequency in patients with genetic generalized epilepsy, though it is unknown whether there is an increased prevalence of sleepwalking or sleep paralysis in genetic generalized epilepsy patients. Establishing this could provide insights into the bio-mechanisms or genetic architecture of both disorders. The aim of this study was to determine the prevalence of sleepwalking and sleep paralysis in a cohort of patients with genetic generalized epilepsy and their relatives in extended families.

METHODS

A structured interview based on International League Against Epilepsy (ILAE) and International Classification of Sleep Disorders (ICSD-3) criteria was applied to 67 index cases and their relatives to determine genetic generalized epilepsy subtypes and assess the occurrence of sleepwalking or sleep paralysis. Bivariate analysis was performed using chi-square and Fisher exact tests.

RESULTS

The prevalence of sleepwalking and sleep paralysis was 15.3% (95% confidence interval 12.1-18.9) and 11.7% (95% confidence interval 8.7-15.3), respectively. Unusually, no sleepwalkers were found among individuals displaying epilepsy with generalized tonic-clonic seizures. Approximately a quarter of the patients had either parasomnia or genetic generalized epilepsy. Over half the genetic generalized epilepsy families had at least 1 individual with sleepwalking, and more than 40% of the families had one individual with sleep paralysis.

CONCLUSION

The prevalence of sleepwalking or sleep paralysis is reported for individuals with genetic generalized epilepsy and their relatives. The co-existence of either parasomnia in the genetic generalized epilepsy patients and the co-aggregation within their families let suggest that shared heritability and pathophysiological mechanisms exist between these disorders. We hypothesize that sleepwalking/sleep paralysis and genetic generalized epilepsy could be variable expression of genes in shared pathways.

Culturally sensitive assessment of anxious-depressive distress in the Cambodian population: Avoiding category truncation

In a large national survey in Cambodia (N = 2689), the present study investigated the prominence of certain culturally salient symptoms and syndromes in the general population and among those with anxious-depressive distress (as determined by the Hopkins Symptom Checklist-25, or HSCL). Using an abbreviated Cambodian Symptom and Syndrome Addendum (CSSA), we found that the CSSA complaints were particularly elevated among those with anxious-depressive distress. Those with anxious-depressive distress had statistically greater mean scores on all the CSSA items as well as severity of endorsement analyzed by percentage: among those with HSCL caseness, 75.3% were bothered "quite a bit" or "extremely" by "thinking a lot" (vs. 27.5% without caseness); 53.8% were bothered by "standing up and feeling dizzy" (vs. 13.8%); and 45.6% by blurry vision (vs. 16.8%). In a logistic regression analysis to predict anxious-depressive distress, 51% of the variance was accounted for by five predictors: "weak heart," "thinking a lot," dizziness, "khyâl hitting up from the stomach," and sleep paralysis. Using ROC analysis, a cut-off score of 1.81 on the CSSA was optimal as a screener to indicate anxious-depressive distress, giving a sensitivity of 0.86. The study results suggest that to avoid category truncation (i.e., the omission of key complaints that are part of an assessed distress domain) when profiling anxious-depressive distress among Cambodia population that items other than those in standard psychopathology measures should be assessed such as "thinking a lot," "weak heart," "blurry vision," and "dizziness upon standing up."

Multiple-dose clinical pharmacology of ACT-541468, a novel dual orexin receptor antagonist, following repeated-dose morning and evening administration

ACT-541468 is a dual orexin receptor antagonist with sleep-promoting effects in humans. Following entry-into-humans, its pharmacokinetics (PK) including dose-proportionality and accumulation, pharmacodynamics (PD), safety, and tolerability following multiple-ascending oral dose (MAD) administration in the morning, and next-day residual effects after repeated evening administration were investigated in a double-blind, placebo-controlled, randomized study. 31 healthy male and female subjects in 3 dose-groups (10, 25, and 75 mg) received study drug in the morning for 5 days (MAD part), and 20 healthy subjects received 25 mg in the evening for 1 week (evening part). PK, PD (saccadic peak velocity (SPV), adaptive tracking, body sway, Bond and Lader visual analogue scales (VAS), Karolinska Sleepiness Scale (KSS), VAS Bowdle for assessment of psychedelic effects), Digit Symbol Substitution Test (DSST), and Simple Reaction Time Test (SRTT), safety, and tolerability were assessed. ACT-541468 was absorbed with a median t_max of 1.0-2.0 h across the 3 dose groups. The geometric mean elimination half-life (t_½) on Day 5 was between 5.6 and 8.5 h, and the exposure (area under the curve (AUC)) showed dose proportionality. No accumulation and no influence of sex on the multiple-dose PK parameters of ACT-541468 was observed. No effects were observed at 10 mg. Administration of 25 and 75 mg during the day showed clear dose-dependent effects on the PD parameters, while next-day effects were absent after evening administration of 25 mg. The drug was safe and well tolerated. In conclusion, multiple-dose PK/PD of ACT-541468 were compatible with a drug designated to treat insomnia.

What do we know about sleep paralysis?

Introduction: Sleep paralysis (SP) is a condition that widely occurs among people all over the world. It has been known for thousands of years and is rooted in the culture of many countries. It arouses strong emotions, though still little is known about it. The clinical picture of the disorder can be very diverse. It is often accompanied by hypnopompic and hypnagogic hallucinations, somatic complaints and the feeling of intense anxiety. A feeling of paralysis in the body with inhibited consciousness is always observed with the experience. SP pathophysiology is not fully understood, however, most theories explaining this phenomenon are based on the assumption that it results from dysfunctional overlap of REM sleep and wakefulness. It is experienced by healthy people, but it is more often associated with somatic and mental disorders, which is why it is becoming an object of interest for researchers.

Aim: The aim of this work is to present the most important information about the disorder known as sleep paralysis - its history, cultural context, pathophysiology, prevalence, symptomatology, coexistence with other somatic and mental disorders as well as diagnostics and available forms of prevention and treatment.

Materials and methodology: The available literature was reviewed using the Google Scholar bibliographic databases searching the following keywords: sleep paralysis, REM sleep parasomnias, sleep disorder, night terrors and time descriptors: 1980-2018.

Results 1. Sleep paralysis has already been described in antiquity, and interpretations related to its occurrence are largely dependent on culture and beliefs.

2. Symptomatology of the disorder is very diverse: both mental and somatic symptoms are present.

3. The pathophysiology of the disorder has not been fully explained. The basis of most theories regarding sleep paralysis is the assumption that it results from the dysfunctional overlap of REM sleep and wakefulness.

4. The prevalence of SP at least once in a lifetime is 7.6% in the general population, although it is estimated that it is much more frequent in people with various mental and somatic disorders.

5. Treatment of SP is associated with a change in lifestyle and the use of pharmacotherapy and psychotherapy.

Dreams of Teeth Falling Out: An Empirical Investigation of Physiological and Psychological Correlates

Teeth dreams (TD), i.e., dreams of teeth falling out or rotting, are one of the most common and universal typical dream themes, yet their source remains unknown and they have rarely been studied empirically. They are especially enigmatic as they do not readily fall under the rubric of the “continuity hypothesis”, i.e., dreams of current and salient waking-life experiences. The aim of the present study was to explore two possible hypotheses for the origin of TD; specifically, TD as incorporation of dental irritation into dreaming, and TD as a symbolic manifestation of psychological distress. Dream themes, dental irritation, psychological distress, and sleep quality were assessed among 210 undergraduates. TD were related to dental irritation (specifically, tension sensations in the teeth, gums, or jaws upon awakening), whereas other dream types were not. Conversely, TD were unrelated to psychological distress, whereas other dream types were (specifically, dreams of being smothered and dreams of falling). This disparity in the correlates of TD existed despite a small but significant relationship between psychological distress and dental irritation. Albeit preliminary, the present findings support the dental irritation hypothesis and do not support the symbolic hypothesis regarding the origins of TD. Research on TD portrays one path through which the mind may distort somatosensory stimuli and incorporate them into dreams as a vivid and emotionally salient image; these preliminary findings highlight the potential of studying TD in order to broaden our understanding of the cognitive mechanisms governing dream production.

Sleep Paralysis, a Medical Condition with a Diverse Cultural Interpretation

Sleep paralysis (SP) is a state associated with the inability to move that occurs when an individual is about sleeping or just waking. It could occur in healthy individuals as isolated SP. It has also been linked with other underlying psychiatry, familial, and sleep disorders. Statistics show that 8% of the general population suffers from SP. Although this value has been described inaccurately, there is no standard definition or etiology to diagnose SP. There are several speculations describing SP in the current literature. These descriptions can be viewed as either cultural-based or medical-based. The disparity among cultural or ethnic groups and medical professionals in identifying SP has led to the various approaches to managing the condition. This review aims to medically describe SP and how it is interpreted and managed among various cultural groups.

Culturally Sensitive Assessment of Anxious-Depressive Distress in Vietnam: Avoiding Category Truncation

The present study investigated what complaints are prominent in psychologically distressed Vietnamese in Vietnam beyond standard symptoms assessed by Western diagnostic instruments for anxiety and depression. To form the initial Vietnamese Symptom and Cultural Syndrome Addendum (VN SSA), we reviewed the literature, consulted experts, and conducted focus groups. The preliminary VN SSA was then used in a general survey (N = 1004) of five provinces in Vietnam. We found that the VN SSA items were highly and significantly correlated with a measure of anxious-depressive psychopathology (a composite measure of the General Anxiety Disorder-7; Posttraumatic Diagnostic Scale; and Patient Health Questionnaire-9). The VN SSA item most highly correlated to anxious-depressive psychopathology was "thinking a lot" ( r = .54), reported by 15.8% of the sample. Many other symptoms in the addendum also were prominent, such as orthostatic dizziness (i.e., dizziness upon standing up; r = .41), reported by 22.9% of the sample. By way of comparison, somatic complaints more typically assessed to profile Western anxious-depressive distress, such as palpitations, were less prominent, as evidenced by being less strongly correlated to Western psychiatric symptoms and being less frequent (e.g., palpitations: r = .31, 7.1% of the sample). Study results suggest that to avoid category truncation when profiling anxious-depressive distress among Vietnamese that items other than those in standard psychopathology measures should also be assessed.

Affective neuroscience of self-generated thought

Despite increasing scientific interest in self-generated thought-mental content largely independent of the immediate environment-there has yet to be any comprehensive synthesis of the subjective experience and neural correlates of affect in these forms of thinking. Here, we aim to develop an integrated affective neuroscience encompassing many forms of self-generated thought-normal and pathological, moderate and excessive, in waking and in sleep. In synthesizing existing literature on this topic, we reveal consistent findings pertaining to the prevalence, valence, and variability of emotion in self-generated thought, and highlight how these factors might interact with self-generated thought to influence general well-being. We integrate these psychological findings with recent neuroimaging research, bringing attention to the neural correlates of affect in self-generated thought. We show that affect in self-generated thought is prevalent, positively biased, highly variable (both within and across individuals), and consistently recruits many brain areas implicated in emotional processing, including the orbitofrontal cortex, amygdala, insula, and medial prefrontal cortex. Many factors modulate these typical psychological and neural patterns, however; the emerging affective neuroscience of self-generated thought must endeavor to link brain function and subjective experience in both everyday self-generated thought as well as its dysfunctions in mental illness.

Sleep Medicine: Parasomnias

Parasomnias are abnormal and undesirable behaviors during sleep and are thought to be due to the sleep state instability. Some of them are benign, while some of them point to a possible underlying neurodegenerative process. This article briefly discusses the clinical characteristics, demographics, and pathophysiology of major parasomnias and associated disorders. The classification outlined in this article conforms to the current version of International Classification of Sleep disorders.