Sleep fragmentation and lucid dreaming

Lucid dreaming—the phenomenon of experiencing waking levels of self-reflection within one’s dreams—is associated with more wake-like levels of neural activation in prefrontal brain regions. In addition, alternating periods of wakefulness and sleep might increase the likelihood of experiencing a lucid dream. Here we investigate the association between sleep fragmentation and lucid dreaming, with a multi-centre study encompassing four different investigations into subjective and objective measures of sleep fragmentation, nocturnal awakenings, sleep quality and polyphasic sleep schedules. Results across these four studies provide a more nuanced picture into the purported connection between sleep fragmentation and lucid dreaming: While self-assessed numbers of awakenings, polyphasic sleep and physiologically validated wake-REM sleep transitions were associated with lucid dreaming, neither self-assessed sleep quality, nor physiologically validated numbers of awakenings were. We discuss these results, and their underlying neural mechanisms, within the general question of whether sleep fragmentation and lucid dreaming share a causal link.     

Sleep and psychopathology

This article examines the relationship between sleep disturbance and psychopathology. Epidemiological, cross-sectional, and longitudinal data suggest a high rate of comorbidity between sleep disturbance and psychopathology, particularly between insomnia, anxiety, and depression. Between 50% and 80% of psychiatric patients complain of sleep disturbances during the acute phase of their illness. Conversely, among treatment-seeking individuals with a primary complaint of insomnia and randomly selected community samples, approximately one third display a concurrent psychopathology, one third exhibit psychological symptoms that do not necessarily exceed the threshold for a psychiatric disorder, and another third present insomnia as a functionally autonomous disorder. There is a positive relationship between severity of sleep disturbances and concurrent psychopathology, but unequivocal evidence of a cause-and-effect relationship is still lacking. However, longitudinal data suggest that anxiety and stressful life events often precede acute sleep difficulties, whereas persistent insomnia may be a risk factor for subsequent development of depression. Implications for the prevention and treatment of coexisting sleep disturbance and psychopathology are discussed.     

Sleep experiences,dissociation, imaginal experiences,and schizotypy: The role of context

Watson (2001) reported moderate correlations between the Iowa Sleep Experience Survey (ISES) and self-report measures of dissociation and schizotypy. Subsequent investigations (Fassler, Knox, & Lynn, 2003; Watson, 2003) reported similar, although somewhat more modest, correlations between the ISES and measures of dissociation and schizotypy, as well as with measures of absorption and negative affect. The present study tested subjects in conditions in which the measures of sleep experiences were administered with other measures in either the same (N = 86) or a different (N = 87) test context. We determined that sleep experiences were associated with measures of dissociation, absorption, and schizotypy. We closely replicated Watson (2001) and found that the ISES correlations with other measures were not affected by the test context. We suggest that Watson’s (2001) hypothesized common domain of unusual cognitive and perceptual experiences (e.g., sleep experiences) may be underpinned by common ties to imaginative experiences.     

Sleep variability and fatigue in adolescents: Associations with school‐related features

This study aims to evaluate the influences of sleep duration and sleep variability (SleepV), upon adolescents' school‐related situations. The Health Behaviour in School‐Aged Children (HBSC) survey is based on a self‐completed questionnaire. The participants were 3164 pupils (53.7% girls), attending the 8th and 10th grades, 14.9 years old, and were inquired about subjective sleep duration during the week and weekends, SleepV, fatigue, difficulties in sleep initiation, school achievement, feelings towards schools, pressure with school work and skipping classes. Multiple regression models used, as dependent variables: (a) school achievement, (b) disliking school, (c) pressure with school work and (d) skipping classes, using as independent variables, each of the remaining school‐related variables, fatigue, total sleep duration and difficulties in sleep initiation. The average sleep duration in the week and during weekdays was lower than recommended for these age groups, and almost half of students had high SleepV between weekdays and weekends. A logistic model revealed that the absence of SleepV was associated with lower perception of school work pressure, less frequent skipping classes, more infrequent fatigue and more infrequent difficulties in sleep initiation. Poor sleep quality, SleepV and insufficient sleep duration affected negatively school‐related variables.     

Sleep: A pathway linking personality to mortality risk

Personality and sleep predict longevity; however, no investigation has tested whether sleep mediates this association. Thus, we tested this effect across a 20-year follow-up (N = 3759) in the Midlife Development in the United States cohort (baseline M_age = 47.15) using proportional hazards in a structural equation modeling framework. Lower conscientiousness predicted increased death risk via the direct, indirect, and total effect of quadratic sleep duration. Although there were no other direct personality-mortality effects, higher neuroticism and agreeableness and lower conscientiousness predicted increased death risk via the joint indirect effects of quadratic sleep duration and higher daytime dysfunction. Lower extraversion predicted increased mortality risk via the indirect effect of daytime dysfunction. Our findings have implications for personality-based health interventions.     

Sleep disturbance and neuropsychological function in young children with ADHD

Sleep disturbance, common among children with ADHD, can contribute to cognitive and behavioral dysfunction. It is therefore challenging to determine whether neurobehavioral dysfunction should be attributed to ADHD symptoms, sleep disturbance, or both. The present study examined parent-reported sleep problems (Children’s Sleep Habits Questionnaire) and their relationship to neuropsychological function in 64 children, aged 4–7 years, with and without ADHD. Compared to typically developing controls, children with ADHD were reported by parents to have significantly greater sleep disturbance—including sleep onset delay, sleep anxiety, night awakenings, and daytime sleepiness—(all p ≤ .01), and significantly poorer performance on tasks of attention, executive control, processing speed, and working memory (all p < .01). Within the ADHD group, total parent-reported sleep disturbance was significantly associated with deficits in attention and executive control skills (all p ≤ .01); however, significant group differences (relative to controls) on these measures remained (p < .01) even after controlling for total sleep disturbance. While sleep problems are common among young children with ADHD, these findings suggest that inattention and executive dysfunction appear to be attributable to symptoms of ADHD rather than to sleep disturbance. The relationships among sleep, ADHD symptoms, and neurobehavioral function in older children may show different patterns as a function of the chronicity of disordered sleep.     

Sleep deprivation impairs object recognition in mice

Many studies in animals and humans suggest that sleep facilitates learning, memory consolidation, and retrieval. Moreover, sleep deprivation (SD) incurred after learning, impaired memory in humans, mice, rats, and hamsters. We investigated the importance of sleep and its timing in an object recognition task in OF1 mice subjected to 6h SD either immediately after the acquisition phase (0-6 SD) or 6h later (7-12 SD), and in corresponding undisturbed controls. Motor activity was continuously recorded with infrared sensors. All groups explored two familiar, previously encountered objects to a similar extent, both at the end of the acquisition phase and 24h later during the test phase, indicating intact familiarity detection. During the test phase 0-6 SD mice failed to discriminate between the single novel and the two familiar objects. In contrast, the 7-12 SD group and the two control groups explored the novel object significantly longer than the two familiar objects. Plasma corticosterone levels determined after SD did not differ from time-matched undisturbed controls, but were significantly below the level measured after learning alone. ACTH did not differ between the groups. Therefore, it is unlikely that stress contributed to the memory impairment. We conclude that the loss of sleep and the activities the mice engaged in during the SD, impaired recognition memory retrieval, when they occurred immediately after acquisition. The delayed SD enabled memory consolidation during the 6h when the mice were allowed to sleep, and had no detrimental effect on memory. Neither SD schedule impaired object familiarity processing, suggesting that only specific cognitive abilities were sensitive to the intervention. Sleep may either actively promote memory formation, or alternatively, sleep may provide optimal conditions of non-interference for consolidation.     

Sleep in children enhances preferentially emotional declarative but not procedural memories

Although the consolidation of several memory systems is enhanced by sleep in adults, recent studies suggest that sleep supports declarative memory but not procedural memory in children. In the current study, the influence of sleep on emotional declarative memory (recognition task) and procedural memory (mirror tracing task) in 20 healthy children (10-13 years of age) was examined. After sleep, children showed an improvement in declarative memory. Separate analysis with respect to the emotional stimulus content revealed that sleep enhances the recognition of emotional stimuli (p > .001) rather than neutral stimuli (p = .084). In the procedural task, however, no sleep-enhanced memory improvement was observed. The results indicate that sleep in children, comparable to adults, enhances predominantly emotional declarative memory; however, in contrast to adults, it has no effect on the consolidation of procedural memory.     

Sleep,resilience, and psychological distress in United States military Veterans

Sleep problems are prevalent among Veterans. Left untreated, such problems may elevate psychological distress and increase risk of subsequent mental health disorders. Psychological resilience may buffer against negative psychological outcomes, yet the relationship between sleep and resilience has not been studied. This study explored poor sleep, resilience, and psychological distress using questionnaires collected as part of the Study of Post-Deployment Mental Health. Participants (N = 1,118) had served in the US military since September 11, 2001, had one or more overseas deployments, and were free from a past-month DSM-defined mental health disorder. Hierarchical linear regression was used to examine the association between poor sleep quality (Pittsburgh Sleep Quality Index total score) and psychological distress (Global Symptom Index; Symptom Checklist-90-R), controlling for demographic and health characteristics. Moderation analyses tested for a potential buffering effect of resilience (Connor-Davidson Resilience Scale). Poor sleeping Veterans had worse physical and psychological health, lower resilience, and endorsed more lifetime traumatic events. Poor sleep was associated with greater psychological distress controlling for health and demographic characteristics. Both resilience factors—adaptability and self-efficacy—had significant buffering effects on the relationship between poor sleep and psychological distress, suggesting that resilience may protect against negative outcomes in poor sleepers. Additional research is warranted to better understand the relationships between sleep, resilience, and psychological distress. Such research may inform pertinent prevention efforts, including interventions that improve sleep, enhance resilience, and protect against incident mental health diagnoses.     

Dreamless Sleep and the Whole of Human Life: An Ontological Exposition

This paper explores the meaning of dreamless sleep. First, I consider four reasons why we commonly pass over sleep’s ontological significance. Second, I compare and contrast death and sleep to show how each is oriented to questions regarding the possibilities of “being-a-whole.” In the third and final part, I explore the meaning and implications of “being-toward-sleep,” arguing that human existence emerges atop naturally anonymous corporeality (i.e. living being). In sum, I try to show that we can recover an authentic – if somewhat ambiguous – sense of “being-a-whole” only by recognizing the ontological significance of dreamless sleep.     

Sleep deprivation adversely affects interpersonal responses to frustration

Sleep deprivation produces negative effects on mood and cognitive function, but existing data have almost exclusively utilized objective rating scales, which do not permit evaluation of idiosyncratic and unstructured responses. In this study, we used a semi-projective measure, the Rosenzweig Picture-Frustration (P-F) Study, to assess subjective responses to frustration following two nights without sleep. Twenty-six healthy volunteers completed the P-F at rested baseline and again following 55 h of continuous wakefulness. Participants provided written responses for an ambiguous cartoon character confronted with various frustrating situations. Relative to rested baseline, sleep deprivation was associated with altered responses on several indices, indicating a great number of uncommon types of responses, increased tendency to blame others for problems, and a reduced willingness to alleviate a conflict situation by accepting blame. Individual differences in several aspects of emotional intelligence were predictive of the extent to which responses to frustration changed with sleep loss. These findings suggest that sleep deprivation significantly weakens the inhibition of aggression and willingness to behave in ways that facilitate effective social interaction, possibly through reduced metabolic activity in prefrontal regions of the brain important for personality, affect, and inhibitory behavior.     

Sleep Quality and Quantity of Occupational Therapy and Other Allied Health Students

Abstract

We examined sleep behaviors in allied health students (N?=?77) with the following questionnaires: Caffeine Consumption, Pittsburgh Sleep Quality Index (PSQI), Profile of Mood States, and Mental and Physical State and Trait Energy and Fatigue Scales. Students averaged 6.56?hr of sleep per night. More than half of the students received borderline or poor sleep quality scores on the PSQI. Students with poor sleep quality had a significantly higher proportion of mood disturbances than students with optimal sleep quality. These results highlight the need for educational programs to emphasize the sleep hygiene practices of their students.     

Sleep deprivation in Air National Guard medical personnel responding to simulated disaster-training exercises

National Guard personnel remain largely unstudied within the sleep research community, despite their unique and important role. In response, the purpose of this study was to investigate the extent of sleep deprivation in National Guard medical personnel from two separate Air Force Bases (AFBs) responding to simulated disaster-training exercises. National Guard medical personnel (N = 77) were fitted with wrist activity monitors (actigraphy) to objectively measure their sleep for 4 days of their civilian time (baseline), followed by a 4-day transition period from civilian to military duty, and a 3–5-day disaster-training exercise. Differences in sleep quantity, quality, and “cognitive effectiveness” were analyzed using generalized linear mixed models. Participants’ sleep quantity was significantly reduced from civilian to disaster-training periods, and their cognitive effectiveness also dropped significantly. National Guard medical personnel were sleep-deprived during a simulated disaster-training exercise, which, although a valid proxy for real-world disasters, is likely to be a conservative approximation of the stress and fatigue National Guard personnel experience during crisis response. As such, the need for targeted fatigue-related interventions to safeguard our service members during these critical times is clear.     

Sleep disruption explains age-related prospective memory deficits: implications for cognitive aging and intervention

The high prevalence of sleep disruption among older adults may have implications for cognitive aging, particularly for higher-order aspects of cognition. One domain where sleep disruption may contribute to age-related deficits is prospective memory—the ability to remember to perform deferred actions at the appropriate time in the future. Community-dwelling older adults (55–93 years, N = 133) undertook assessment of sleep using actigraphy and participated in a laboratory-based prospective memory task. After controlling for education, sleep disruption (longer awakenings) was associated with poorer prospective memory. Additionally, longer awakenings mediated the relationship between older age and poorer prospective memory. Other metrics of sleep disruption, including sleep efficiency and wake after sleep onset, were not related to prospective memory, suggesting that examining the features of individual wake episodes rather than total wake time may help clarify relationships between sleep and cognition. The mediating role of awakening length was partially a function of greater depression and poorer executive function (shifting) but not retrospective memory. This study is among the first to examine the association between objectively measured sleep and prospective memory in older adults. Furthermore, this study is novel in suggesting sleep disruption might contribute to age-related prospective memory deficits; perhaps, with implications for cognitive aging more broadly. Our results suggest that there may be opportunities to prevent prospective memory decline by treating sleep problems.     

Sleep duration associates with moderate-to-vigorous intensity physical activity and body fat in 1- to 3-year-old children

Sleep during early childhood is important for many developmental outcomes and shows promise as an important correlate of both obesity risk and physical activity behaviors. This was a cross-sectional study concerning the relationships between sleep and moderate- to – vigorous intensity physical activity and body fat percentage in a sample of 1- to 3-year-old children (N = 50; ages 27.512 ± 10.363 months). Sleep was measured with a caregiver questionnaire. Sedentary time, light, moderate, vigorous, and moderate- to – vigorous intensity physical activity were measured with Actigraph wT3x-BT accelerometers. Body fat was measured using Air Displacement Plethysmography with the BodPod Pediatric Option. Moderate- to – vigorous intensity physical activity and body fat percentage both associated with sleep duration, controlling for age and accelerometer wear time. These factors combined explained 54.3 % of the variance in sleep duration present in the sample. These results suggest the presence of relationships between sleep and physical activity and body composition constructs in this sample. Sleep may be an important variable in efforts to both promote early childhood physical activity and healthy body composition.     

Sleep interventions for performance,mood and sleep outcomes in athletes: A systematic review and meta-analysis

Sleep is fundamental to sports performance and other health outcomes such as mental wellbeing. This systematic review explored the effects of sleep interventions implemented among athletes on performance, sleep, and mood outcomes. Five databases were searched, returning 5996 records for screening. Of these, 27 articles met the inclusion criteria (16 controlled deigns, 11 uncontrolled; athletes n = 617; male n = 432, female n = 93, non-binary/other n = 0 or not reported n = 92). Narrative synthesis of all studies based on intervention type suggested that sleep hygiene, assisted sleep, and sleep extension interventions may be associated with improved sleep, performance, and mood outcomes. Twelve controlled trials were eligible for quantitative meta-analysis, investigating the effect of sleep interventions on athlete sleep, performance, and negative affect, compared to controls post-intervention. Utilizing random-effects meta-analyses, sleep interventions improved subjective sleep quality (g = 0.62, 95% CI [0.21, 1.02]), reduced sleepiness (g = 0.81, 95% CI [0.32, 1.30]) and decreased negative affect (g = 0.63, 95% CI [0.27, 0.98]), but did not appear to influence subjective sleep duration. No effects were identified for objective sleep measures (e.g., actigraphy), or aerobic/anaerobic performance indices. While sleep interventions may offer some benefit to athletes, caution is warranted given limitations of the extant research relating to small, non-representative studies with methodological concerns.     

Further Evidence That Sleep Deprivation Effects and the Vigilance Decrement Are Functionally Equivalent: Comment on Altmann (2018)

Veksler and Gunzelmann (2018) argue that the vigilance decrement and the deleterious effects of sleep loss reflect functionally equivalent degradations in cognitive processing and performance. Our account is implemented in a cognitive architecture, where these factors produce breakdowns in goal‐directed cognitive processing that we refer to as microlapses. Altmann (2018) raises a number of challenges to microlapses as a unified account of these deficits. Under scrutiny, however, the challenges do little to discredit the theory or conclusions in the original paper. In our response, we address the most serious challenges. In so doing, we provide additional support for the theory and mechanisms, and we highlight opportunities for extending their explanatory breadth.     

Sleep, watchkeeping and accidents: a content analysis of incident at sea reports

The unique profession of seafaring involves rest and sleep in a 24-h-a-day work environment that usually involves time-zone crossings, noise, heat, cold and motion. Sleep under such conditions is often difficult to obtain, and sleeping and sleep loss are often related to fatigue and contributory to accidents. This study aims to determine how accident investigators report sleep in Incident at Sea Reports and subsequently analyse the relationships between sleep, fatigue and accidents in these reports.The full text of 44 Incident at Sea Reports was coded and analysed using NUDIST software. This sample included collisions and groundings reported since 1991, where significant human factors contributed to the incident. The Incident at Sea Reports were electronically searched for reference to sleep and content was indexed against parameters such as fatigue behaviours, time of day and contributing personnel. Incident at Sea Reports incorporate three levels of reference to sleep, analysis of which may associate sleeping and sleepiness with accident causation. The highest level of reference unequivocally associates either being asleep, or being sleep deprived with accidents, but not always with fatigue. At an intermediate level, reference to the conflicting pressures of work and sleep on board fishing boats and ships suggests a work environment that is not conducive to obtaining sufficient sleep, and accident investigators are usually unable to link the watchkeeping environment with fatigue as a contributing factor. At the lowest level of association, reference is made to the integrated nature of sleeping and work on board.     

Sleep deprivation and sustained attention performance: integrating mathematical and cognitive modeling

A long history of research has revealed many neurophysiological changes and concomitant behavioral impacts of sleep deprivation, sleep restriction, and circadian rhythms. Little research, however, has been conducted in the area of computational cognitive modeling to understand the information processing mechanisms through which neurobehavioral factors operate to produce degradations in human performance. Our approach to understanding this relationship is to link predictions of overall cognitive functioning, or alertness, from existing biomathematical models to information processing parameters in a cognitive architecture, leveraging the strengths from each to develop a more comprehensive explanation. The integration of these methodologies is used to account for changes in human performance on a sustained attention task across 88 h of total sleep deprivation. The integrated model captures changes due to time awake and circadian rhythms, and it also provides an account for underlying changes in the cognitive processes that give rise to those effects. The results show the potential for developing mechanistic accounts of how fatigue impacts cognition, and they illustrate the increased explanatory power that is possible by combining theoretical insights from multiple methodologies.