Human sleep, sleep loss and behaviour. Implications for the prefrontal cortex and psychiatric disorder

Early childhood sleep quantity, but not caregiver-reported sleep problems, predicts impulse control in children at age 8 years

Short duration of sleep and poor sleep quality have been linked to poor attention and impulse control in children. We aimed to determine the longitudinal predictive value of sleep quantity and quality during early childhood on objective and caregiver-report measures of attention, impulse control, and executive function in children at age 8 years. We used data from the Health Outcomes and Measures of the Environment (HOME) Study, a pregnancy and birth cohort. Caregivers reported on their child's sleep at ages 2, 2.5, 3, 4, and 5 years. Analysis included 410 participants. We used longitudinal growth curve models of early childhood sleep patterns to predict neurobehavioral functioning at age 8 years. Sleep problems did not predict any of our outcome measures at age 8 years. Sleep duration trended shorter as children matured, so predictive models examined both intercept and slope. Children with the least decline in sleep duration across early childhood had fewer impulsive errors at age 8 years on a continuous performance test (unadjusted p = .013; adjusted p = .013). Children with shorter duration of sleep across early childhood had worse caregiver-reported behavioral regulation at age 8 years (unadjusted p = .002; adjusted p = .043). Neither sleep duration slope nor intercept predicted inattention or metacognitive skills at age 8 years (p > .05). Total sleep time across early childhood predicts behavior regulation difficulties in school-aged children. Inadequate sleep during early childhood may be a marker for, or contribute to, poor development of a child's self-regulatory skills.

Sleepiness in retired male boxers: daytime sleepiness and its relationship with impulsiveness and depression symptomatology in retired professional male boxers

BACKGROUND

Boxing exposes fighters to head impacts and potential traumatic brain injury (TBI). Though research has explored the neuropsychiatric consequences of contact sports, there is limited research into Excessive Daytime Sleepiness (EDS) and its relationship to other outcomes, such as impulsiveness and depression. Therefore, this study aimed to describe EDS in retired boxers using the Epworth Sleepiness Scale (ESS) and to examine how boxing and sleepiness relate to impulsiveness and depression symptomatology.

METHODS

86 male retired professional boxers from the Professional Fighters Brain Health Study (PFBHS) met the inclusion criteria. Adjusted multivariable models analyzed relationships between professional boxing bouts, EDS (ESS), impulsiveness (Barratt Impulsiveness Scale Version 11 (BIS-11)), and/or depression (Patient Health Questionnaire-9 (PHQ-9)). A causal mediation analysis was performed to assess whether boxing bouts and ESS scores predicted BIS-11 and PHQ-9 scores.

RESULTS

Mean age was ∼51 years, fighters averaged ∼36 professional bouts, and ESS mean(SD) was 7.5(5.3). ESS scores were significantly associated with raw BIS-11 (Beta = 1.26, 95%CI = 0.77-1.75, p < 0.001) and ordinal PHQ-9 (OR = 1.20, 95%CI = 1.11-1.31, p < 0.001) scores in adjusted models, and the significant relationship between boxing bouts and BIS-11/PHQ-9 was mediated by ESS.

CONCLUSIONS

EDS in retired male professional boxers may be strongly associated with other neuropsychiatric sequelae of TBI (impulsiveness and depression).Sleepiness; sleep; boxing; contact sports; impulsiveness; impulsivity; depression; Epworth sleepiness scale box.

Sleep and mental health among Chinese adolescents: the chain-mediating role of physical health perception and school adjustment

OBJECTIVE

Sleep problems and their detrimental effects on adolescents' physical and mental health have received substantial attention. Prior studies have focused mainly on the direct association between sleep and mental health; however, little is known about the underlying mediating mechanism. To address this gap, the present study constructed a chain mediation model to examine the association between sleep deficiency and mental health status in adolescents, by introducing two mediating variables-physical health perception and school adjustment.

METHODS

A sample of 7530 senior high school students completed a battery of self-report questionnaires measuring their sleep duration, mental health status, physical health perception, and school adjustment. Data were collected from the Database of Youth Health at Shandong University. All the measures showed good reliability and validity in the present study. Data were analyzed using SPSS 25.0 and the SPSS PROCESS.

RESULTS

The results were as follows: (1) Sleep duration was significantly associated with physical health perception and mental health. (2) Physical health perception partially mediated the association between sleep and mental health. (3) Physical health perception and school adjustment played a chain mediating role between sleep and mental health. In conclusion, sleep not only directly associated with mental health among adolescents, but also influences mental health by the chain mediating effect of perception of physical health and school adjustment.

CONCLUSION

These findings in the present study contribute to understanding the mechanisms underlying the association between sleep and mental health and have important implications for interventions aimed at improving mental health status among adolescents in China. Our results indicated that promoting adequate sleep duration and improving sleep quality are possible key mental health promotion strategies for adolescents.

Circadian modulation of the time course of automatic and controlled semantic processing

We investigated whether chronotype and time-of-day modulate the time course of automatic and controlled semantic processing. Participants performed a category semantic priming task at either the optimal or non-optimal time of day. We varied the prime-target onset asynchrony (100-, 450-, 650-, and 850-ms SOAs) and kept the percentage of unrelated targets constant at 80%. Automatic processing was expected with the short SOA, and controlled processing with longer SOAs. Intermediate-types (Experiment 1) verified that our task was sensitive to capturing both types of processes and served as a reference to assess themin extreme chronotypes. Morning-type and evening-type participants (Experiment 2) differed in the influence of time of testing on priming effects. Morning-types applied control in all conditions, and no performance modulation by time-of-day was observed. In contrast, evening-types were most adversely affected by the time of day to shift from automatic-based to controlled-based responses. Also, they were considerably affected in successfully implementing controlled processing with long intervals, particularly at the non-optimal time of day, with inhibitory priming showing only a marginally significant effect at the longest SOA. These results suggest that extreme chronotypes may be associated with different styles of cognitive control. Morning-types would be driven by a proactive control style, whereas a reactive control style might be applied by evening-types.

Fundamentals of sleep regulation: Model and benchmark values for fractal and oscillatory neurodynamics

Homeostatic, circadian and ultradian mechanisms play crucial roles in the regulation of sleep. Evidence suggests that ratios of low-to-high frequency power in the electroencephalogram (EEG) spectrum indicate the instantaneous level of sleep pressure, influenced by factors such as individual sleep-wake history, current sleep stage, age-related differences and brain topography characteristics. These effects are well captured and reflected in the spectral exponent, a composite measure of the constant low-to-high frequency ratio in the periodogram, which is scale-free and exhibits lower interindividual variability compared to slow wave activity, potentially serving as a suitable standardization and reference measure. Here we propose an index of sleep homeostasis based on the spectral exponent, reflecting the level of membrane hyperpolarization and/or network bistability in the central nervous system in humans. In addition, we advance the idea that the U-shaped overnight deceleration of oscillatory slow and fast sleep spindle frequencies marks the biological night, providing somnologists with an EEG-index of circadian sleep regulation. Evidence supporting this assertion comes from studies based on sleep replacement, forced desynchrony protocols and high-resolution analyses of sleep spindles. Finally, ultradian sleep regulatory mechanisms are indicated by the recurrent, abrupt shifts in dominant oscillatory frequencies, with spindle ranges signifying non-rapid eye movement and non-spindle oscillations - rapid eye movement phases of the sleep cycles. Reconsidering the indicators of fundamental sleep regulatory processes in the framework of the new Fractal and Oscillatory Adjustment Model (FOAM) offers an appealing opportunity to bridge the gap between the two-process model of sleep regulation and clinical somnology.

Sex as a moderator of the sleep and cognition relationship in middle-aged and older adults: A preliminary investigation

OBJECTIVES

Despite known sex differences in the prevalence of sleep disturbance and cognitive impairment, research investigating sex differences in sleep/cognition associations is limited. We examined sex as a moderator of associations between self-reported sleep and objective cognition in middle-aged/older adults.

METHODS

Adults aged 50+ (32 men/31 women, Mage = 63.6 ± 7.7) completed the Pittsburgh Sleep Quality Index (PSQI) and cognitive tasks: Stroop (processing speed, inhibition), Posner (spatial attentional orienting) and Sternberg (working memory). Multiple regressions examined whether PSQI metrics (global score, sleep quality ratings, sleep duration, sleep efficiency) were independently or interactively (with sex) associated with cognition, controlling for age and education.

RESULTS

Sex interacted with sleep quality ratings in its association with endogenous spatial attentional orienting (∆R2 = .10, p = .01). Worse ratings of sleep quality were associated with worse orienting in women (B = 22.73, SE = 9.53, p = .02), not men (p = .24). Sex interacted with sleep efficiency in its associations with processing speed (∆R2 = .06, p = .04). Lower sleep efficiency was associated with slower Stroop control trial performance in women (B = -15.91, SE = 7.57, p = .04), not men (p = .48).

CONCLUSIONS

Preliminary findings suggest middle-aged/older women are more vulnerable to associations between poor sleep quality and low sleep efficiency on spatial attentional orienting and processing speed, respectively. Future studies in larger samples investigating sex-specific prospective sleep and cognition associations are warranted.

Are physical activity and sleep associated with emotional self-regulation in toddlers? a cross-sectional study

BACKGROUND

Toddlerhood (2-3 years) is a crucial period for the development of physical activity, sleep, and emotional self-regulation skills. Although there is growing evidence of positive associations between physical activity, sleep, and emotional self-regulation in school-aged children, the associations in toddlers remain unclear. Thus, this study aimed to examine the association between physical activity, sleep, and emotional self-regulation in toddlers.

METHODS

Baseline data from 1350 toddlers (2.2 ± 0.33 year) from the Let's Grow randomised controlled trial were used. Toddlers' total physical activity (TPA) and moderate- to vigorous-intensity physical activity (MVPA) were assessed via 4 + days of accelerometry and a 3-item parent-report scale. Parent-reported total sleep quantity was calculated using the sum of average night-time sleep and daytime nap durations. Sleep behaviour data including bedtime routine, bedtime resistance, sleep onset-delay, sleep duration, and night waking were collected using relevant subsections from the Child Sleep Habits Questionnaire (CSHQ) and Brief Infant Sleep Questionnaire revised (BISQ-R). A 4-item parent-report scale adapted from the Fast Track Project Child Behaviour Questionnaire was used to assess toddlers' emotional self-regulation. Linear regression models were used, adjusting for child age, sex, and parental education.

RESULTS

Accelerometer-derived TPA, MVPA and parent-reported TPA were not associated with emotional self-regulation. Higher parent-reported MVPA (B = -0.01 CI95 -0.03, -0.003) was associated with poorer emotional self-regulation. Higher sleep duration was associated with better emotional self-regulation (B = 0.06 CI95 0.04, 0.08). The five sleep behaviours assessed were also positively associated with emotional self-regulation (all p < 0.01), with fewer problem sleep behaviours being associated with better emotional self-regulation.

CONCLUSIONS

This cross-sectional study suggests that sleep may be important for emotional self-regulation in toddlers, but the role of physical activity remains unclear. These findings suggest that interventions targeting sleep duration and sleep behaviours during the early toddler years may benefit the positive development of emotional self-regulation skills in this population.

Do sleep disruptions promote social fragmentation?

Sleep changes predate shifts in mood/affect, thought processing, mental and physical health, civic engagement, and contextual circumstances, among other things. Theory predicts that these changes may lead to shifts in political and social beliefs. Do sleep disruptions shape how individuals see the world, the people around them, and themselves in relation to others? In this article, we use daily survey data from the 77 waves (N ≈ 460,000) of the University of California, Los Angeles's 2019-2021 Nationscape Survey-a nationally representative political survey-to examine the effect of an exogenous short-term sleep disruption on measures of political views, polarization, and discriminatory beliefs. Using this data set, we leverage the modest sleep disruption that occurs at the start (and end) of Daylight Saving Time (DST) and employ a regression discontinuity in time design around the precise DST cutoff (which we supplement with event study models). Despite strong theoretical expectations and correlational connection between measures of sleep and many outcomes related to social fragmentation, we find that the DST change has little to no causal effect on citizens' levels of polarization or their discriminatory attitudes. These effects are precise enough to rule out small effects, robust to a host of specification checks, and consistent across potential subgroups of interest. Our work adds to a small but growing body of research on the social and political effects of sleep disruptions.

Nocturnal sleep duration trajectories in early childhood and school performance at age 10 years

Sleep plays a fundamental role in brain development and resultant functions. The aim was to verify whether nocturnal sleep duration during early childhood has long-term associations with academic achievement at age 10 years. The present study is part of the Quebec Longitudinal Study of Child Development, a representative cohort of infants born in 1997-1998 in the province of Quebec, Canada. Children with known neurological conditions were excluded from this cohort. Four trajectories of parent-reported nocturnal sleep duration at ages 2.5, 3, 4, 5 and 6 years were determined using a SAS procedure named PROC TRAJ. Sleep duration at age 10 years was also reported. Teachers provided data on academic performance when the children were age 10 years. These data were available for 910 children (430 boys, 480 girls; 96.6% Caucasians). Univariate and multivariable logistic regressions were performed using SPSS. Children who slept less than 8 hr per night at 2.5 years but normalized later on (Traj1) had three-five times the odds of having grades below the class average in reading, writing, mathematics and science compared with children who slept sufficiently (Traj3-4: 10-11 hr per night). Children who slept about 9 hr per night throughout childhood (Traj2) had two-three times the odds of being below the class average in mathematics and science. Sleep duration at age 10 years was not correlated with the academic performance. These results point to the presence of a very important early period during which sufficient sleep is needed to fine-tune the functions necessary for academic achievement later on.

How the time-of-day affects the EEG signatures of vigilance fluctuation

Previous research suggested the homeostatic effect on the top-down control system as a major factor for daytime vigilance decrement, yet how it alters the cognitive processes of vigilance remains unclear. Using EEG, the current study measured the vigilance of 28 participants under three states: the morning, the midafternoon after napping and no-nap. The drift-diffusion model was applied to decompose vigilant reaction time into decision and non-decision components. From morning to midafternoon, vigilance declined during sustained wakefulness, but remained stable after midday napping. Increased sleep pressure negatively affected decision time and drift rate, but did not significantly alter the non-decision process. Frontocentral N2 amplitude decreased from morning to no-nap afternoon, associated with slowing decision time. In contrast, parietal P3 had no diurnal alterations during sustained wakefulness, but enhanced after napping. Pre-stimulus parietooccipital alpha power enhanced under high sleep pressure relative to low, accompanied by more lapses in no-nap vs. post-napping conditions. The homeostasis effect is a major contributor to daily vigilance fluctuation, specifically targeting top-down control processes during the pre-stimulus and decision-making stages. Under the influence of sleep homeostasis, the speed of decision-making declines with degradation in target monitoring from morning to afternoon, leading to post-noon vigilance decrement.

Bidirectional association between sleep quality or duration and aggressive behaviour in early adolescents: A cross-lagged longitudinal study

BACKGROUND

Several cross-sectional studies have suggested a strongly positive link between sleep and aggressive behaviour; however, longitudinal studies reporting the relationship between sleep and aggressive behaviour are lacking. This study aimed to examine whether a bidirectional relationship exists between sleep quality or duration and aggressive behaviour in early adolescents.

METHODS

A total of 1579 early adolescents (60.9 % boys) from the Chinese Early Adolescents Cohort study were included in this study. Data on sleep quality, sleep duration and aggressive behaviour collected at two time points (September 2019 and September 2021) were used, and the bidirectional relationship between sleep quality or duration and aggressive behaviour was examined using a cross-lagged model.

RESULTS

The results revealed a bidirectional relationship between low sleep quality and highly aggressive behaviour. A shorter sleep duration did not predict highly aggressive behaviour, whereas only highly aggressive behaviour predicted a shorter sleep duration.

CONCLUSIONS

Sleep quality and aggressive behaviour were interrelated over time among adolescents. However, sleep duration did not predict aggressive behaviour, suggesting that sleep quality, instead of sleep duration, should be the primary target for managing aggressive behaviour.

Sleep and dreaming in the light of reactive and predictive homeostasis

Dreams are often viewed as fascinating but irrelevant mental epihenomena of the sleeping mind with questionable functional relevance. Despite long hours of oneiric activity, and high individual differences in dream recall, dreams are lost into oblivion. Here, we conceptualize dreaming and dream amnesia as inherent aspects of the reactive and predictive homeostatic functions of sleep. Mental activity during sleep conforms to the interplay of restorative processes and future anticipation, and particularly during the second half of the night, it unfolds as a special form of non-constrained, self-referent, and future-oriented cognitive process. Awakening facilitates constrained, goal-directed prospection that competes for shared neural resources with dream production and dream recall, and contributes to dream amnesia. We present the neurophysiological aspects of reactive and predictive homeostasis during sleep, highlighting the putative role of cortisol in predictive homeostasis and forgetting dreams. The theoretical and methodological aspects of our proposal are discussed in relation to the study of dreaming, dream recall, and sleep-related cognitive processes.

Trajectories of reported sleep duration associate with early childhood cognitive development

STUDY OBJECTIVES

Examine how different trajectories of reported sleep duration associate with early childhood cognition.

METHODS

Caregiver-reported sleep duration data (n = 330) were collected using the Brief Infant Sleep Questionnaire at 3, 6, 9, 12, 18, and 24 months and Children's Sleep Habits Questionnaire at 54 months. Multiple group-based day-, night-, and/or total sleep trajectories were derived-each differing in duration and variability. Bayley Scales of Infant and Toddler Development-III (Bayley-III) and the Kaufman Brief Intelligence Test- 2 (KBIT-2) were used to assess cognition at 24 and 54 months, respectively.

RESULTS

Compared to short variable night sleep trajectory, long consistent night sleep trajectory was associated with higher scores on Bayley-III (cognition and language), while moderate/long consistent night sleep trajectories were associated with higher KBIT-2 (verbal and composite) scores. Children with a long consistent total sleep trajectory had higher Bayley-III (cognition and expressive language) and KBIT-2 (verbal and composite) scores compared to children with a short variable total sleep trajectory. Moderate consistent total sleep trajectory was associated with higher Bayley-III language and KBIT-2 verbal scores relative to the short variable total trajectory. Children with a long variable day sleep had lower Bayley-III (cognition and fine motor) and KBIT-2 (verbal and composite) scores compared to children with a short consistent day sleep trajectory.

CONCLUSIONS

Longer and more consistent night- and total sleep trajectories, and a short day sleep trajectory in early childhood were associated with better cognition at 2 and 4.5 years.

Sleep and Mental Health Problems in Children and Adolescents

Previous reviews have described the links between sleep and mental health extensively. In this narrative review, we focus on literature published during the last decade investigating the links between sleep and mental health difficulties in childhood and adolescence. More specifically, we focus on the mental health disorders listed in the most recent edition of the Diagnostic and Statistical Manual of Mental Disorders. We also discuss possible mechanisms underlying these associations. The review ends with a discussion of possible future lines of enquiry.

Impairment of executive functions due to sleep alterations: An integrative review on the use of P300

Objective

Cognitive impairment due to sleep deprivation (SD) is an important global health concern as part of the growing rates of sleep disorders and sleep deprivation worldwide. Amongst the affected cognitive processes, the effects of SD on the executive functions (EFs) show diverse methods and inconclusive or contradictory results, highlighting the importance of further research in this field. Considering this scenario, we evaluate one of the most used methods for objectively evaluating EFs on SD: the event-related potential (ERP) P300.

Methods

Our study provides a comprehensive review on the use of P300 for evaluating executive functions in sleep alterations on subjects of all ages, as well as an analysis on the efficiency of P300 as an assessment method for executive functions compared to traditional neurocognitive batteries. We review the benefits of P300 application for multiple sleep/wake alterations, whether evoked in laboratory or as part of pre-existing sleep disorders.

Results

We assess the diverse protocols used to elicit and complement P300, the most identified alterations in amplitude and latency, and suggest new lines of study that could benefit from P300 within the field.

Conclusion

We conclude that P300 is a valuable asset for evaluating executive dysfunction under sleep deprivation both as a standalone protocol and in conjunction with subjective methods, with consistently significant results in assessing executive dysfunction in a diversity of subjects and etiologies.

The Brain and Early Experience Study: Protocol for a Prospective Observational Study

BACKGROUND

Children raised in conditions of poverty (or near poverty) are at risk for nonoptimal mental health, educational, and occupational outcomes, many of which may be precipitated by individual differences in executive function (EF) skills that first emerge in early childhood.

OBJECTIVE

The Brain and Early Experience study considers prenatal and postnatal experiences that may mediate the association between poverty and EF skills, including neural substrates. This paper described the study rationale and aims; research design issues, including sample size determination, the recruitment strategy, and participant characteristics; and a summary of developmental assessment points, procedures, and measures used to test the study hypotheses.

METHODS

This is a prospective longitudinal study examining multiple pathways by which poverty influences normative variations in EF skills in early childhood. It is funded by the National Institute of Child Health and Human Development and approved by the institutional review board.

RESULTS

Recruitment is complete with a sample of 203 participants, and data collection is expected to continue from September 2018 to February 2024. Of those recruited as low socioeconomic status (SES), 71% (55/78) reported income-to-needs (ITN) ratios of <2.0, and 35% (27/78) reported ITN ratios of <1.0. Among participants recruited into the not-low SES stratum, only 8.8% (11/125) reported ITN ratios of <2.0, and no participant reported ITN ratios of <1.0. The average ITN ratio for participants recruited into the low-income stratum was significantly lower than the average for the high-income recruitment cell (P<.001). Comparable recruitment outcomes were observed for both Black and non-Black families. Overall, the sample has adequate diversity for testing proposed hypotheses, with 13.3% (27/203) of participants reporting ITN ratios of <1 and >32.5% (66/203) reporting ratios of <2.0.

CONCLUSIONS

Preliminary results indicate that the recruitment strategy for maximizing variation in family SES was successful, including variation within race. The findings of this study will help elucidate the complex interplay between prenatal and postnatal risk factors affecting critical neurocognitive developmental outcomes in early childhood.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/34854.

A Comprehensive Review of the Literature on Sleep Difficulties and Suicidality in Youth to Inform an Integrative Developmental Model and Future Directions

Purpose of Review

Suicide is currently the second leading cause of death among youth. Identification of modifiable near-term risk factors can inform suicide prevention strategies. One promising, readily assessed factor is sleep. We critically review the literature on sleep and suicidal thoughts and behaviors among youth.

Recent Findings

Most studies examining the youth sleep-suicidality relationship are from epidemiological samples in which both sleep problems and suicidality were assessed over variable timeframes using limited items from scales not designed to measure these constructs. Nonetheless, these data overwhelmingly support an association between suicidality and a range of sleep difficulties (e.g., insomnia, short/long sleep, weekend oversleep), above and beyond depressive symptoms. Limited studies include clinical samples or prospective designs. We review potential mechanisms and present a developmentally-informed integrative model.

Summary

Literature supports a clear association between sleep difficulties and youth suicidality. Future directions include prospective longitudinal studies and targeted prevention efforts.

Assessment of subjective sleep quality and issues in aggression: Intermittent Explosive Disorder compared with psychiatric and healthy controls

BACKGROUND

While prior research has linked clinical sleep issues and aggression, little is known about how clinical sleep issues among individuals with Intermittent Explosive Disorder (IED), which is characterized by a pervasive pattern of impulsive aggression and associated with consequences across multiple life-domains. The present study aims to examine clinical sleep issues among individuals with IED in contrast to individuals with other psychopathology and healthy controls.

METHODS

257 adults, including 100 healthy controls, 85 psychiatric controls and 72 individuals with IED, took part in this study. Participants completed the Structured Clinical Interview for DSM-V Diagnoses, Assessment of clinical sleep issues included the Pittsburgh Sleep Quality Inventory (PSQI), obstructive sleep apnea (OSA) screening, and the Epworth Sleepiness Scale (ESS) as well as assessments of aggression and impulsivity.

RESULTS

IED study participants reported significantly worse sleep quality, increased sleep latency, greater daytime sleepiness and symptoms of OSA. Daytime sleepiness and sleep quality was correlated with impulsivity and aggression.

CONCLUSIONS

This study suggests that individuals with IED have clinically relevant sleep anomalies, and that these are directly associated with measures of impulsivity and aggression. Clinicians treating aggressive individuals are advised to assess and treat such individuals for sleep issues.

Shorter Duration and Lower Quality Sleep Have Widespread Detrimental Effects on Developing Functional Brain Networks in Early Adolescence

Sleep is critical for cognitive health, especially during complex developmental periods such as adolescence. However, its effects on maturating brain networks that support cognitive function are only partially understood. We investigated the impact of shorter duration and reduced quality sleep, common stressors during development, on functional network properties in early adolescence-a period of significant neural maturation, using resting-state functional magnetic resonance imaging from 5566 children (median age = 120.0 months; 52.1% females) in the Adolescent Brain Cognitive Development cohort. Decreased sleep duration, increased sleep latency, frequent waking up at night, and sleep-disordered breathing symptoms were associated with lower topological efficiency, flexibility, and robustness of visual, sensorimotor, attention, fronto-parietal control, default-mode and/or limbic networks, and with aberrant changes in the thalamus, basal ganglia, hippocampus, and cerebellum (P < 0.05). These widespread effects, many of which were body mass index-independent, suggest that unhealthy sleep in early adolescence may impair neural information processing and integration across incompletely developed networks, potentially leading to deficits in their cognitive correlates, including attention, reward, emotion processing and regulation, memory, and executive control. Shorter sleep duration, frequent snoring, difficulty waking up, and daytime sleepiness had additional detrimental network effects in nonwhite participants, indicating racial disparities in the influence of sleep metrics.

Prefrontal Cortex Metabolome Is Modified by Opioids, Anesthesia, and Sleep

Obtundation of wakefulness caused by opioids and loss of wakefulness caused by anesthetics and sleep significantly alter concentrations of molecules comprising the prefrontal cortex (PFC) metabolome. Quantifying state-selective changes in the PFC metabolome is essential for advancing functional metabolomics. Diverse functions of the PFC suggest the PFC metabolome as a potential therapeutic entry point for countermeasures to state-selective autonomic dysfunction.

Gulf War veterans exhibit broadband sleep EEG power reductions in regions overlying the frontal lobe

AIMS

Nearly a third of U.S. veterans who deployed in support of the 1990-1991 Persian Gulf War are affected by Gulf War illness (GWI). Here we aimed to characterize whether subjective sleep complaints in GWI veterans are associated with objective sleep EEG disturbances relative to healthy veterans and controls; and whether Gulf War veterans show alterations in neural activity during sleep that differentiate them from healthy subjects.

MAIN METHODS

We used high-density EEG (HDEEG) to assess regional patterns of rapid eye movement (REM) sleep and non-REM (NREM) sleep between three groups: Gulf War male veterans with fatigue and GWI, Gulf War male veterans without fatigue or GWI, and control males. The groups were matched relative to age, sex and obstructive sleep apnea. Topographic comparisons of nocturnal NREM and REM sleep were made between groups for all frequency bands.

KEY FINDINGS

Topographic analysis revealed a broadband reduction in EEG power in a circumscribed region overlying the frontal lobe in both groups of Gulf War veterans, regardless of GWI and fatigue. This frontal reduction in neural activity was present, to some extent, across all frequency bands in NREM and REM sleep.

SIGNIFICANCE

Given that our findings were observed in all Gulf War veterans, it appears unlikely that frontal sleep HDEEG power reductions prove wholly responsible for fatigue symptoms. These results provide avenues for research which may someday contribute to improved clinical care of formerly deployed veterans of the Persian Gulf War.

Physical Activity and Inhibitory Control: The Mediating Role of Sleep Quality and Sleep Efficiency

Objectives: the current study aimed to investigate the relationship between physical activity (PA) level and inhibitory control performance and then to determine whether this association was mediated by multiple sleep parameters (i.e., subjective sleep quality, sleep duration, sleep efficiency, and sleep disturbance). Methods: 180 healthy university students (age: 20.15 ± 1.92 years) from the East China Normal University were recruited for the present study. PA level, sleep parameters, and inhibitory control performance were assessed using the International Physical Activity Questionnaire (IPAQ), the Pittsburgh Sleep Quality Index Scale (PSQI), and a Stroop test, respectively. The data were analyzed using structural equation modeling. Results: A higher level of PA was linked to better cognitive performance. Furthermore, higher subjective sleep quality and sleep efficiency were associated with better inhibitory control performance. The mediation analysis revealed that subjective sleep quality and sleep efficiency mediated the relationship between PA level and inhibitory control performance. Conclusion: our results are in accordance with the literature and buttress the idea that a healthy lifestyle that involves a relatively high level of regular PA and adequate sleep patterns is beneficial for cognition (e.g., inhibitory control performance). Furthermore, our study adds to the literature that sleep quality and sleep efficiency mediates the relationship between PA and inhibitory control performance, expanding our knowledge in the field of exercise cognition.

'Investigating longitudinal associations between parent reported sleep in early childhood and teacher reported executive functioning in school-aged children with autism'

Up to 80% of children with autism spectrum disorder (ASD) experience sleep disturbance. Poor sleep impairs executive functioning (EF), a lifelong difficulty in ASD. Evidence suggests EF difficulties in ASD are exacerbated by poor sleep. We examine whether early childhood sleep disturbances are associated with worsening EF trajectories in school-aged children with ASD. A subsample (n=217) from the Pathways in ASD longitudinal study was analyzed. The Children's Sleep Habits Questionnaire captured sleep duration, onset, and night awakenings before age 5 (Mean=3.5years). Metacognition (MI) and Behavioral Regulation (BRI) indices, on the Teacher Behavior Rating Inventory of Executive Functioning, were used to measure cognitive and affective components of EF respectively at four time-points (7.8-11.8years). We applied latent growth curve models to examine associations between sleep and EF, accounting for relevant covariates, including school-age sleep (Mean=6.7years). Sleep traits had different age-related impacts on behavioral regulation, but not metacognition. Longer sleep onset at 3.5 years was associated with a worsening BRI difficulties slope (b=2.07, p<0.04), but conversely associated with lower BRI difficulties at 7.7 years (b=-4.14, p=0.04). A longer sleep onset at 6.7 years was related to higher BRI difficulties at 7.7 years (b=7.78, p<0.01). Longer sleep duration at 6.7 years was associated with higher BRI difficulties at age 7.7 (b=3.15, p=0.01), but subscale analyses revealed shorter sleep duration at age 6.7 was linked to a worsening inhibition slope (b=-0.60, p=0.01). Sleep onset is a robust early correlate of behavior regulation in children with ASD, whereas sleep duration is a later childhood correlate.

Sleep deprivation and compensatory cognitive effort on a visual information processing task

STUDY OBJECTIVES

Total sleep deprivation (TSD) is often associated with worse performance on tasks of attention and working memory, but some studies show no performance changes. One possibility is that greater compensatory cognitive effort is put forth to achieve similar results after TSD. We aimed to better understand the relationship between TSD, cognitive engagement, and performance outcomes following TSD.

METHODS

Twenty healthy adults completed cognitive testing following a night of normal sleep and again after ~55 hours of TSD. Participants detected target letters in low (3-item) and high (10-item) load visual letter displays on the span of apprehension task with concurrent pupillometry, a measure of cognitive effort.

RESULTS

We found significantly poorer detection accuracy and marginally longer response times following TSD across both arrays. In both arrays, significantly greater preparatory pupillary responses were found just prior to array onset. There was also a significant session by array interaction for pupillary responses, such that significantly greater dilation was found for the 3-letter array after TSD, while a nonsignificant decline in dilation was found following the 10-letter array after TSD.

CONCLUSIONS

These results suggest a complex relationship between attentional control and cognitive resource allocation following TSD. Sleep-deprived individuals may allocate more compensatory cognitive effort to easier tasks but choose to disengage from more challenging cognitive tasks that have little perceived reward or probability of success to preserve diminishing cognitive resources. More work is needed to better delineate the underlying neurological systems involved in these processing load-dependent attentional control mechanisms after TSD.

Experimentally imposed circadian misalignment alters the neural response to monetary rewards and response inhibition in healthy adolescents

BACKGROUND

Sleep and circadian timing shifts later during adolescence, conflicting with early school start times, and resulting in circadian misalignment. Although circadian misalignment has been linked to depression, substance use, and altered reward function, a paucity of experimental studies precludes the determination of causality. Here we tested, for the first time, whether experimentally-imposed circadian misalignment alters the neural response to monetary reward and/or response inhibition.

METHODS

Healthy adolescents (n = 25, ages 13-17) completed two in-lab sleep schedules in counterbalanced order: An 'aligned' condition based on typical summer sleep-wake times (0000-0930) and a 'misaligned' condition mimicking earlier school year sleep-wake times (2000-0530). Participants completed morning and afternoon functional magnetic resonance imaging scans during each condition, including monetary reward (morning only) and response inhibition (morning and afternoon) tasks. Total sleep time and circadian phase were assessed via actigraphy and salivary melatonin, respectively.

RESULTS

Bilateral ventral striatal (VS) activation during reward outcome was lower during the Misaligned condition after accounting for the prior night's total sleep time. Bilateral VS activation during reward anticipation was lower during the Misaligned condition, including after accounting for covariates, but did not survive correction for multiple comparisons. Right inferior frontal gyrus activation during response inhibition was lower during the Misaligned condition, before and after accounting for total sleep time and vigilant attention, but only during the morning scan.

CONCLUSIONS

Our findings provide novel experimental evidence that circadian misalignment analogous to that resulting from school schedules may have measurable impacts on healthy adolescents' reward processing and inhibition of prepotent responses.

Sleep and self-regulation in early childhood

What is the role of sleep in children's behavioral, emotional, and cognitive regulation? This chapter considers theoretical and conceptual links between sleep and self-regulation, with special attention to sleep and self-regulation in early childhood. We selectively review the growing body of research on associations between sleep and self-regulation, mentioning some methodological issues. We also consider how child characteristics and sociocontextual factors may interact with sleep in the development of self-regulation in early childhood. We provide some relevant empirical examples from our own research.

Sleep problems in children and adolescents following traumatic life events

Rates of childhood trauma exposure are extremely high, with approximately 70% of children and adolescents experiencing at least one traumatic event. Among the most common non-specific consequences of stress and trauma are disruptions of sleep. Sleep problems, such as shorter sleep duration, difficulty falling asleep, frequent awakenings, nightmares, sleepless nights, and early-morning wakefulness appear to have a higher prevalence among children and adolescents following traumatic events. This review will illustrate the role of sleep problems in traumatized children and adolescents, and emphasize the need to consider a wide range of etiological mechanisms for these symptoms. However, the relationship of trauma exposure to sleep problems among children and adolescents needs further investigation in future research. Moreover, in view of the adverse consequences of long-term disrupted sleep on mental health outcomes following trauma, the need to effectively address sleep disturbances in traumatized children and adolescents is crucial.

The effect of sleep on public good contributions and punishment: Experimental evidence

We investigate the effect of a full week of sleep restriction (SR) vs. well-restedness (WR) on contributions in a common public good experiment, the voluntary contributions mechanism (VCM). We examine the effect of sleep manipulation on decisions regarding both contributions and punishment of non-contributors. Actigraphy devices are used to confirm that our random assignment to sleep condition generates significant differences in objective nightly sleep duration and sleepiness. We find that when punishment is unavailable public good contributions do not differ by SR/WR assignment. When punishment is available, we find evidence that SR subjects contribute more than WR subjects, respond more to the availability of punishment than do WR subjects, and that the availability of punishment significantly increases the contributions of SR but not WR subjects. Yet SR subjects do not punish others more or less than WR subjects. Our main findings are robust when considering compliance and sample selection. However, some findings are not robust to an alternative but less objective sleep control measure that is based partly on participants' self-identified optimal sleep levels.

Do sleep disturbances contribute to cognitive impairments in schizophrenia spectrum and bipolar disorders?

Sleep disturbances and cognitive impairments are both frequent across psychotic disorders, with debilitating effects on functioning and quality of life. This study aims to investigate if sleep disturbances are related to cognitive impairments in schizophrenia spectrum (SCZ) and bipolar disorders (BD), if this relationship varies between different sleep disturbances (insomnia, hypersomnia or delayed sleep phase (DSP)) and lastly, if this relationship differs between clinical groups and healthy controls (HC). We included 797 patients (SCZ = 457, BD = 340) from the Norwegian Centre for Mental Disorders Research (NORMENT) study in Norway. Sleep disturbances were based on items from the Inventory of Depressive Symptoms-Clinician rated scale (IDS-C). Their relationship with several cognitive domains was tested using separate ANCOVAs. A three-way between-groups ANOVA was conducted to test if the relationship with cognitive impairments varies between different sleep disturbances. These analyses revealed significantly poorer processing speed and inhibition in those with any sleep disturbance versus those without, also after adjusting for several covariates. The relationship between sleep disturbances and cognition was similar across SCZ and BD, and there were significant effects of insomnia and hypersomnia on both processing speed and inhibition. No association between sleep disturbances and cognition was found in HC. Sleep disturbances contribute to cognitive impairments in psychotic disorders. Processing speed and inhibition is poorer in patients with sleep disturbances. Impairments in these domains are related to insomnia and hypersomnia. These findings suggest that treating sleep disturbances is important to protect cognitive functioning, alongside cognitive remediation in psychotic disorders.

Alteration of Brain Gray Matter Density After 24 h of Sleep Deprivation in Healthy Adults

It has been reported that one night of acute sleep deprivation (SD) could induce brain structural changes at the synaptic and neuronal levels in animal studies, and could lead to white matter microstructure and cortical thickness change in human neuroimaging studies. In this study, we focused on changes of brain gray matter density (GMD) after one night of acute SD, which has not been explored previously. Twenty-three normal young participants completed the experiment. Each participant underwent twice T1-weighted structural image scanning with one at 08:00 after normal sleep [resting wakeful (RW)] and the other at 08:00 after 24 h of SD. Using voxel-based morphometry (VBM) analysis by FSL-VBM software, we compared GMD between RW and SD. In addition, the gray matter volume (GMV) and cortical thickness (CT) were also calculated based on volumetric and surface measures with FreeSurfer software. The psychomotor vigilance test (PVT) and the Karolinska Sleepiness Scale (KSS) were performed and evaluated for correlation analysis with GMD, GMV, and CT of the significant regions. Our results showed that the GMD in the right frontal pole (FP), right superior frontal gyrus (SFG), and right middle frontal gyrus significantly increased and GMV and CT in the right temporal pole (TP) significantly decreased after 24 h of acute SD. SD-induced changes in GMD in the right middle frontal gyrus were positively correlated with the changes of KSS scores (Spearman’s correlation r = 0.625, p = 0.0014, Bonferroni correction with p < 0.05/25). Taken together, our findings suggested that one night of acute SD could induce substantial brain structure changes and the alterations in GMD in the right middle frontal gyrus (MFG) might be implicated in sleepiness after SD.

Perceived Threat of COVID-19 Contagion and Frontline Paramedics' Agonistic Behaviour: Employing a Stressor-Strain-Outcome Perspective

Historically, infectious diseases have been the leading cause of human psychosomatic strain and death tolls. This research investigated the recent threat of COVID-19 contagion, especially its impact among frontline paramedics treating patients with COVID-19, and their perception of self-infection, which ultimately increases their agonistic behaviour. Based on the stressor-strain-outcome paradigm, a research model was proposed and investigated using survey-based data through a structured questionnaire. The results found that the perceived threat of COVID-19 contagion (emotional and cognitive threat) was positively correlated with physiological anxiety, depression, and emotional exhaustion, which led toward agonistic behaviour. Further, perceived social support was a key moderator that negatively affected the relationships between agonistic behaviour and physiological anxiety, depression, and emotional exhaustion. These findings significantly contributed to the current literature concerning COVID-19 and pandemic-related effects on human behaviour. This study also theorized the concept of human agonistic behaviour, which has key implications for future researchers.

Pre-experimental sleep effects on directed forgetting

A directed forgetting (DF) paradigm was used to compare the remembering and forgetting of participants with good sleep quality to those with poor sleep quality and the presence of insomnia symptoms. This study implemented a point system in place of remember and forget instructions in a DF task with the goal of computing DF costs and benefits. Relations among memory, sleep, and working memory capacity (WMC) were also examined. DF benefits were observed in both groups, with negative costs found for participants without the presence of insomnia symptoms. WMC was found to be related to memory for positive point items only, and did not differ based on sleep quality. These results suggest that the presence of self-reported insomnia symptoms does not affect performance on a DF task.

Automatically Detected Microsleep Episodes in the Fitness-to-Drive Assessment

Study Objectives: Microsleep episodes (MSEs) are short fragments of sleep (1–15 s) that can cause dangerous situations with potentially fatal outcomes. In the diagnostic sleep-wake and fitness-to-drive assessment, accurate and early identification of sleepiness is essential. However, in the absence of a standardised definition and a time-efficient scoring method of MSEs, these short fragments are not assessed in clinical routine. Based on data of moderately sleepy patients, we recently developed the Bern continuous and high-resolution wake-sleep (BERN) criteria for visual scoring of MSEs and corresponding machine learning algorithms for automatic MSE detection, both mainly based on the electroencephalogram (EEG). The present study aimed to investigate the relationship between automatically detected MSEs and driving performance in a driving simulator, recorded in parallel with EEG, and to assess algorithm performance for MSE detection in severely sleepy participants.

Methods: Maintenance of wakefulness test (MWT) and driving simulator recordings of 18 healthy participants, before and after a full night of sleep deprivation, were retrospectively analysed. Performance of automatic detection was compared with visual MSE scoring, following the BERN criteria, in MWT recordings of 10 participants. Driving performance was measured by the standard deviation of lateral position and the occurrence of off-road events.

Results: In comparison to visual scoring, automatic detection of MSEs in participants with severe sleepiness showed good performance (Cohen’s kappa = 0.66). The MSE rate in the MWT correlated with the latency to the first MSE in the driving simulator (r_s = −0.54, p < 0.05) and with the cumulative MSE duration in the driving simulator (r_s = 0.62, p < 0.01). No correlations between MSE measures in the MWT and driving performance measures were found. In the driving simulator, multiple correlations between MSEs and driving performance variables were observed.

Conclusion: Automatic MSE detection worked well, independent of the degree of sleepiness. The rate and the cumulative duration of MSEs could be promising sleepiness measures in both the MWT and the driving simulator. The correlations between MSEs in the driving simulator and driving performance might reflect a close and time-critical relationship between sleepiness and performance, potentially valuable for the fitness-to-drive assessment.

A Bump on the Head or Late to Bed: Behavioral and Pathophysiological Effects of Sleep Deprivation after Repetitive Mild Traumatic Brain Injury in Adolescent Rats

An old wives' tale, and strongly held dogma, maintains that one should be kept awake after a mild traumatic brain injury (mTBI) to prevent a coma. This, however, conflicts with the known benefits of sleep: repair and restoration. We therefore sought to examine the effects of sleep deprivation (SD) in the post-traumatic sleep period on post-concussion symptomology (PCS). Adolescent male and female rats were administered repetitive mTBIs (RmTBI) or sham injuries and were then assigned to 5 h of SD or left undisturbed. All animals were then tested using seven behavioral tasks validated to examine PCS, followed by analysis of serum cytokines, and quantitative real-time PCR for messenger RNA (mRNA) expression. Exposure to 3 SD epochs significantly impaired behavior in 4 of 7 of the measures, while RmTBI also produced dysfunction in 5 of 7 tests, but the effects of SD and RmTBI were not cumulative. SD induced long-lasting changes in serum levels of Tnf-α, IL6, and IL-1ß. mRNA expression in the pre-frontal cortex, hippocampus, hypothalamus, and anterior cingulate cortex was modified in response to SD and RmTBI; but similar to the behavioral measures, the mRNA changes were not cumulative. Consequently, we report that SD often produced impairments similar or worse than RmTBI, and sleep hygiene should become a priority for adolescent health.

Cognitive performance in patients with implantable cardioverter defibrillators: Associations with objective sleep duration, age and anxiety

Sleep disturbance and anxiety are highly prevalent in patients with implantable cardiac defibrillators (ICDs). There is limited research, however, on the associations between cognitive performance and sleep parameters, age and anxiety. Forty-one patients with ICDs and self-reported sleep disturbance completed 14 days of actigraphy (Mage  = 60.3, SD = 12.3) measuring total sleep time (TST), and a computerized cognitive test battery measuring processing speed and attention (i.e. simple reaction time and symbol digit modality task [SDMT]) and executive function (i.e. flanker task, letter series task and N-back task). Multiple regressions determined whether independent effects of TST, age and anxiety, as well as interactive effects of TST and age, predicted cognitive performance. TST predicted performance on two tasks of executive function (i.e. letter series and N-back task), as well as an attentional vigilance and processing speed task (i.e. SDMT), and this did not depend on patient age. On letter series, N-back and SDMT, longer TST predicted better performance. Increasing age was a predictor of worse performance on SDMT and flanker tasks. No other predictors were associated with task performance. Results show that sleep duration, not anxiety, may be an important predictor of higher-order cognitive functioning and lower-order tasks measuring processing speed and attention in ICD patients, with longer sleep duration showing greater benefit for performance.

The Spatiotemporal Pattern of the Human Electroencephalogram at Sleep Onset After a Period of Prolonged Wakefulness

During the sleep onset (SO) process, the human electroencephalogram (EEG) is characterized by an orchestrated pattern of spatiotemporal changes. Sleep deprivation (SD) strongly affects both wake and sleep EEG, but a description of the topographical EEG power spectra and oscillatory activity during the wake-sleep transition after a period of prolonged wakefulness is still missing. The increased homeostatic sleep pressure should induce an earlier onset of sleep-related EEG oscillations. The aim of the present study was to assess the spatiotemporal EEG pattern at SO following SD. A dataset of a previous study was analyzed. We assessed the spatiotemporal EEG changes (19 cortical derivations) during the SO (5 min before vs. 5 min after the first epoch of Stage 2) of a recovery night after 40 h of SD in 39 healthy subjects, analyzing the EEG power spectra (fast Fourier transform) and the oscillatory activity [better oscillation (BOSC) detection method]. The spatiotemporal pattern of the EEG power spectra mostly confirmed the changes previously observed during the wake-sleep transition at baseline. The comparison between baseline and recovery showed a wide increase of the post- vs. pre-SO ratio during the recovery night in the frequency bins ≤10 Hz. We found a predominant alpha oscillatory rhythm in the pre-SO period, while after SO the theta oscillatory activity was prevalent. The oscillatory peaks showed a generalized increase in all frequency bands from delta to sigma with different predominance, while beta activity increased only in the fronto-central midline derivations. Overall, the analysis of the EEG power replicated the topographical pattern observed during a baseline night of sleep but with a stronger intensity of the SO-induced changes in the frequencies ≤10 Hz, and the detection of the rhythmic activity showed the rise of several oscillations at SO after SD that was not observed during the wake-sleep transition at baseline (e.g., alpha and frontal theta in correspondence of their frequency peaks). Beyond confirming the local nature of the EEG pattern at SO, our results show that SD has an impact on the spatiotemporal modulation of cortical activity during the falling-asleep process, inducing the earlier emergence of sleep-related EEG oscillations.

Insufficient sleep reduces voting and other prosocial behaviours

Insufficient sleep is a growing public health concern in industrial societies. Although a lack of sleep is known to negatively affect private behaviours-such as working or going to school-comparatively little is known about its consequences for the social behaviours that hold society and democracy together. Using three complementary methods, we show how insufficient sleep affects various measures of civic participation. With survey data from two countries, we show that insufficient sleep predicts lower voter turnout. Next, with a geographical regression discontinuity design, we demonstrate that individuals from the United States who tend to sleep less due to circadian impacts of time-zone boundaries are also less likely to vote. Finally, we experimentally manipulate short-term sleep over a two-stage study. We observe that the treatment decreases the levels of civic engagement, as shown by their willingness to vote, sign petitions and donate to charities. These results highlight the strong negative consequences that current levels of insufficient sleep have on vitally important measures of social capital.

Neurobiological mechanisms underlying the sleep-pain relationship in adolescence: A review

Adolescence characterizes a period of significant change in brain structure and function, causing the neural circuitry to be particularly susceptible to the environment and various other experiences. Chronic pain and sleep deprivation represent major health issues that plague adolescence. A bidirectional relationship exists between sleep and pain; however, emerging evidence suggests that sleep disturbances have a stronger influence on subsequent pain than vice versa. The neurobiological underpinnings of this relationship, particularly during adolescence, are poorly understood. This review examines the current literature regarding sleep and pain in adolescence, with a particular focus on the neurobiological mechanisms underlying pain, sleep problems, and the neural circuitry that potentially links the two. Finally, a research agenda is outlined to stimulate future research on this topic. Given the high prevalence of these health issues during adolescence and the debilitating effects they inflict on nearly every domain of development, it is crucial that we determine the neurobiological mechanisms fundamental to this relationship and identify potential therapeutic strategies.

Strong relationship between NREM sleep, epilepsy and plastic functions - A conceptual review on the neurophysiology background

The aim of this review is to summarize and discuss the strong bond between NREM sleep and epilepsy underlain by the shared link and effect on brain plasticity. Beyond the seizure occurrence rate, sleep relatedness may manifest in the enhancement of interictal epileptic discharges (spikes and pathological ripples). The number of the discharges as well as their propagation increase during NREM sleep, unmasking the epileptic network that is hidden during wakefulness. The interictal epileptic discharges associate with different sleep constituents (sleep slow waves, spindling and high frequency oscillations); known to play essential role in memory and learning. We highlight three major groups of epilepsies, in which sleep-related plastic functions suffer an epileptic derailment. In absence epilepsy mainly involving the thalamo-cortical system, sleep spindles transform to generalized spike-wave activity. In mesio-temporal epilepsy affecting the hippocampal declarative memory system, the sharp wave ripples derail to dysfunctional epileptic oscillations (spikes and pathological ripples). Idiopathic childhood epilepsies affecting the perisylvian network may progress to catastrophic status electricus during NREM sleep. In these major epilepsies, NREM sleep has a pivotal role in the development and course of the disorder. Epilepsy is born in-, and exhibits its pathological properties during NREM sleep. Interictal discharges are important causative agents in this process.

Sleep and mindfulness meditation as they relate to false memory

By a systematic analysis of the current literature, we compare two states of sleep and meditation in terms of their role in the formation or suppression of Deese-Roediger-McDermott (DRM) false memory. We aim to suggest that the occurrence of false memory under these two states is a result of reinforcing some abilities and changes in cognitive systems which can ultimately improve some aspects of cognitive functions. In our analogy, we propose that: (1) both sleep and meditation may improve source monitoring ability whose failure is one of the most important mechanisms in producing false memories, and (2) despite improvement in source monitoring ability, adaptive cognitive processes, as mechanisms which are common in sleep and meditation, can still produce false memories. In conclusion, we propose that in spite of their contribution to false memory through adaptive processes, the beneficial role of sleep and meditation in cognition may be more prominent than their harmful role.

Executive Functions and Their Relation to Sleep Following Mild Traumatic Brain Injury in Preschoolers

OBJECTIVES

Traumatic brain injury (TBI) sustained during childhood is known to impact children's executive functioning. However, few studies have focused specifically on executive functioning after preschool TBI. TBI has also been associated with sleep disturbances, which are known to impair executive functions in healthy children. The aim of this study was to investigate executive functions in preschoolers with mild TBI, and to determine the role of sleep in the links between TBI and executive functioning.

METHODS

The sample was drawn from a longitudinal study and included 167 children, aged 18 to 60 months, divided into 2 groups: children with accidental mild TBI (n=84) and typically developing children (n=83). Children were assessed 6 months post-injury on executive function measures (inhibition and cognitive flexibility) and sleep measures (actigraphy data and parental rating of sleep problems).

RESULTS

The two groups did not differ in their executive abilities. However, relative to controls, children with mild TBI and shorter nighttime sleep duration or increased sleep problems exhibited poorer executive functions.

CONCLUSIONS

These results support a "double hazard" effect, whereby the combination of sleep disturbances and mild TBI results in poorer executive functions. The findings highlight the importance of assessing and monitoring the quality of sleep even after mild head injuries. Poor sleep may place children at risk for increased cognitive difficulties. (JINS, 2018, 24, 769-780).