Showing papers on "Sleep (system call) published in 2023"

Sleep cycle-dependent vascular dynamics in male mice and the predicted effects on perivascular cerebrospinal fluid flow and solute transport

Abstract: Abstract Perivascular spaces are important highways for fluid and solute transport in the brain enabling efficient waste clearance during sleep. However, the underlying mechanisms augmenting perivascular flow in sleep are unknown. Using two-photon imaging of naturally sleeping male mice we demonstrate sleep cycle-dependent vascular dynamics of pial arteries and penetrating arterioles: slow, large-amplitude oscillations in NREM sleep, a vasodilation in REM sleep, and a vasoconstriction upon awakening at the end of a sleep cycle and microarousals in NREM and intermediate sleep. These vascular dynamics are mirrored by changes in the size of the perivascular spaces of the penetrating arterioles: slow fluctuations in NREM sleep, reduction in REM sleep and an enlargement upon awakening after REM sleep and during microarousals in NREM and intermediate sleep. By biomechanical modeling we demonstrate that these sleep cycle-dependent perivascular dynamics likely enhance fluid flow and solute transport in perivascular spaces to levels comparable to cardiac pulsation-driven oscillations.

Cognitive Performance in Short Sleep Young Adults with Different Physical Activity Levels: A Cross-Sectional fNIRS Study

Abstract: Short sleep is a common issue nowadays. The purpose of this study was to investigate prefrontal cortical hemodynamics by evaluating changes in concentrations of oxygenated hemoglobin (HbO) in cognitive tests among short-sleep young adults and to explore the relationship between sleep duration, physical activity level, and cognitive function in this specific population. A total of 46 participants (25 males and 21 females) were included in our study, and among them, the average sleep duration was 358 min/day. Stroop performance in the short sleep population was linked to higher levels cortical activation in distinct parts of the left middle frontal gyrus. This study found that moderate-to-vigorous physical activity (MVPA) was significantly associated with lower accuracy of incongruent Stroop test. The dose-response relationship between sleep duration and Stroop performance under different levels of light-intensity physical activity (LPA) and MVPA was further explored, and increasing sleep time for different PA level was associated with better Stroop performance. In summary, this present study provided neurobehavioral evidence between cortical hemodynamics and cognitive function in the short sleep population. Furthermore, our findings indicated that, in younger adults with short sleep, more MVPA was associated with worse cognitive performance. Short sleep young adults should increase sleep time, rather than more MVPA, to achieve better cognitive function.

Memory consolidation during sleep involves context reinstatement in humans

Abstract: New memories aren’t quarantined from each other when first encoded; rather, they are interlinked with memories that were encoded in temporal proximity or share semantic features. By selectively biasing memory processing during sleep, here we test whether context influences sleep-consolidation. Participants first formed 18 idiosyncratic narratives, each linking four objects together. Before sleep,they also memorized an on-screen position for each object. During sleep, 12 object-specific sounds were unobtrusively presented, thereby cuing the corresponding spatial memories and impacting spatial recall as a function of initial memory strength. As hypothesized, we find that recall for non-cued objects contextually linked with cued objects also changed. Post-cue electrophysiological responses suggest that activity in the sigma band supports context reinstatement and predicts context-related memory benefits. Concurrently, context-specific electrophysiological activity patterns emerge during sleep. We conclude that reactivation of individual memories during sleep evokes reinstatement of their context, thereby impacting consolidation of associated knowledge.

Melatonin as a Chronobiotic with Sleep-promoting Properties

Abstract: Abstract: The use of exogenous melatonin (exo-MEL) as a sleep-promoting drug has been under extensive debate due to the lack of consistency of its described effects. In this study, we conduct a systematic and comprehensive review of the literature on the chronobiotic, sleep-inducing, and overall sleep-promoting properties of exo-MEL. To this aim, we first describe the possible pharmacological mechanisms involved in the sleep-promoting properties and then report the corresponding effects of exo-MEL administration on clinical outcomes in: a) healthy subjects, b) circadian rhythm sleep disorders, c) primary insomnia. Timing of administration and doses of exo-MEL received particular attention in this work. The exo-MEL pharmacological effects are hereby interpreted in view of changes in the physiological properties and rhythmicity of endogenous melatonin. Finally, we discuss some translational implications for the personalized use of exo-MEL in the clinical practice.

Total Sleep Deprivation Increases Brain Age Prediction Reversibly in Multisite Samples of Young Healthy Adults

Abstract: Sleep loss pervasively affects the human brain at multiple levels. Age-related changes in several sleep characteristics indicate that reduced sleep quality is a frequent characteristic of aging. Conversely, sleep disruption may accelerate the aging process, yet it is not known what will happen to the age status of the brain if we can manipulate sleep conditions. To tackle this question, we used an approach of brain age to investigate whether sleep loss would cause age-related changes in the brain. We included MRI data of 134 healthy volunteers (mean chronological age of 25.3 between the age of 19 and 39 years, 42 females/92 males) from five datasets with different sleep conditions. Across three datasets with the condition of total sleep deprivation (>24 h of prolonged wakefulness), we consistently observed that total sleep deprivation increased brain age by 1–2 years regarding the group mean difference with the baseline. Interestingly, after one night of recovery sleep, brain age was not different from baseline. We also demonstrated the associations between the change in brain age after total sleep deprivation and the sleep variables measured during the recovery night. By contrast, brain age was not significantly changed by either acute (3 h time-in-bed for one night) or chronic partial sleep restriction (5 h time-in-bed for five continuous nights). Together, the convergent findings indicate that acute total sleep loss changes brain morphology in an aging-like direction in young participants and that these changes are reversible by recovery sleep. SIGNIFICANCE STATEMENT Sleep is fundamental for humans to maintain normal physical and psychological functions. Experimental sleep deprivation is a variable-controlling approach to engaging the brain among different sleep conditions for investigating the responses of the brain to sleep loss. Here, we quantified the response of the brain to sleep deprivation by using the change of brain age predictable with brain morphologic features. In three independent datasets, we consistently found increased brain age after total sleep deprivation, which was associated with the change in sleep variables. Moreover, no significant change in brain age was found after partial sleep deprivation in another two datasets. Our study provides new evidence to explain the brainwide effect of sleep loss in an aging-like direction.

Understanding the Neural Mechanisms of General Anesthesia from Interaction with Sleep–Wake State: A Decade of Discovery

Abstract: The development of cutting-edge techniques to study specific brain regions and neural circuits that regulate sleep–wake brain states and general anesthesia (GA), has increased our understanding of these states that exhibit similar neurophysiologic traits. This review summarizes current knowledge focusing on cell subtypes and neural circuits that control wakefulness, rapid eye movement (REM) sleep, non-REM sleep, and GA. We also review novel insights into their interactions and raise unresolved questions and challenges in this field. Comparisons of the overlapping neural substrates of sleep–wake and GA regulation will help us to understand sleep–wake transitions and how anesthetics cause reversible loss of consciousness. Significance Statement General anesthesia (GA), sharing numerous neurophysiologic traits with the process of natural sleep, is administered to millions of surgical patients annually. In the past decade, studies exploring the neural mechanisms underlying sleep–wake and GA have advanced our understanding of their interactions and how anesthetics cause reversible loss of consciousness. Pharmacotherapies targeting the neural substrates associated with sleep–wake and GA regulations have significance for clinical practice in GA and sleep medicine.

Contactless Camera-Based Sleep Staging: The HealthBed Study

Abstract: Polysomnography (PSG) remains the gold standard for sleep monitoring but is obtrusive in nature. Advances in camera sensor technology and data analysis techniques enable contactless monitoring of heart rate variability (HRV). In turn, this may allow remote assessment of sleep stages, as different HRV metrics indirectly reflect the expression of sleep stages. We evaluated a camera-based remote photoplethysmography (PPG) setup to perform automated classification of sleep stages in near darkness. Based on the contactless measurement of pulse rate variability, we use a previously developed HRV-based algorithm for 3 and 4-class sleep stage classification. Performance was evaluated on data of 46 healthy participants obtained from simultaneous overnight recording of PSG and camera-based remote PPG. To validate the results and for benchmarking purposes, the same algorithm was used to classify sleep stages based on the corresponding ECG data. Compared to manually scored PSG, the remote PPG-based algorithm achieved moderate agreement on both 3 class (Wake–N1/N2/N3–REM) and 4 class (Wake–N1/N2–N3–REM) classification, with average κ of 0.58 and 0.49 and accuracy of 81% and 68%, respectively. This is in range with other performance metrics reported on sensing technologies for wearable sleep staging, showing the potential of video-based non-contact sleep staging.

Sleep Irregularity and Subclinical Markers of Cardiovascular Disease: The Multi‐Ethnic Study of Atherosclerosis

Abstract: Background Sleep irregularity has been linked to incident cardiovascular disease. Less is known about associations of sleep regularity with atherosclerosis. We examined cross-sectional associations of actigraphy-assessed sleep duration and sleep timing regularity with subclinical atherosclerosis in the community-based MESA (Multi-Ethnic Study of Atherosclerosis). Methods and Results MESA Sleep Ancillary Study participants (N=2032; mean age, 68.6±9.2 years; 37.9% White) completed 7-day wrist actigraphy. Participants underwent assessments of coronary artery calcium, carotid plaque presence, carotid intima-media thickness, and the ankle-brachial index. Sleep regularity was quantified by the 7-day with-in person SD of sleep duration and sleep onset timing. Relative risk regression models were used to calculate prevalence ratios and 95% CIs. Models are adjusted for demographics, cardiovascular disease risk factors, and other objectively assessed sleep characteristics including obstructive sleep apnea, sleep duration, and sleep fragmentation. After adjustment, compared with participants with more regular sleep durations (SD ≤60 minutes), participants with greater sleep duration irregularity (SD >120 minutes) were more likely to have high coronary artery calcium burden (>300; prevalence ratio, 1.33 [95% CI, 1.03-1.71]) and abnormal ankle-brachial index (<0.9; prevalence ratio, 1.75 [95% CI, 1.03-2.95]). Compared with participants with more regular sleep timing (SD ≤30 minutes), participants with irregular sleep timing (SD >90 minutes) were more likely to have high coronary artery calcium burden (prevalence ratio, 1.39 [95% CI, 1.07-1.82]). Associations persisted after adjustment for cardiovascular disease risk factors and average sleep duration, obstructive sleep apnea, and sleep fragmentation. Conclusions Sleep irregularity, particularly sleep duration irregularity, was associated with several measures of subclinical atherosclerosis. Sleep regularity may be a modifiable target for reducing atherosclerosis risk. Future investigation into cardiovascular risk reduction interventions targeting sleep irregularity may be warranted.

Poor Sleep Quality in Aging: The Association with Mental Health

Abstract: Sleep disturbances are common in the elderly. A primary sleep disorder can result from the physiological decline of aging; however, secondary sleep problems result from various causes involving physical and mental health. Since little is known about the relationships between sleep quality and mental health in aging, the present study aims to understand how different aspects generally associated with sleep (e.g., psychological and physiological factors, and sleep medication) may predict poor sleep quality in different stages of the lifespan. Therefore, we conducted several analyses (ANOVAs, Pearson correlations, and linear regressions) to test the hypotheses of the study. Accordingly, from a pool of 180 participants (elderly, middle-aged, and young adults), 143 individuals with poor sleep quality were selected. Different predictive patterns in the three groups emerged. Specifically, the use of sleep medication associated with worse sleep conditions is predicted by poor sleep quality in the elderly and by depression in young adults. In contrast, worsening sleep quality is predicted by depression in middle-aged adults. Previous studies focused on the transitions from good to poor sleep quality, while this is the first study to have examined the features of poor sleep quality in aging, highlighting different sleep patterns across the lifespan. This evidence should be considered from a preventive perspective.

How can general dental practitioners help in the management of sleep apnoea?

Abstract: This article discusses the aetiology, prevalence and treatment of obstructive sleep apnoea (OSA) and highlights the important role general dental practitioners can perform in improving the quality of life of patients suffering from OSA. Clinical and laboratory stages of making a mandibular advancement appliance are also highlighted.Members of the dental team have a duty of care to our patients. The earlier undiagnosed cases of OSA are referred for treatment, the less morbidity and potential mortality endured by patients.After reading this article, the reader should have a greater understanding of OSA, how to identify symptoms of the condition in patients and be confident in referring patients to appropriate healthcare professionals.

Patient-reported outcomes for measuring sleep disturbance in pediatric atopic dermatitis: Cross-sectional study of the Patient Reported Outcomes Measurement Information System pediatric sleep measures and actigraphy

Abstract: Most children with atopic dermatitis (AD) experience sleep disturbance, but reliable and valid assessment tools are lacking.To test the Patient-Reported Outcomes Measurement Information System (PROMIS) sleep measures in pediatric AD and to develop an algorithm to screen, assess, and intervene to reduce sleep disturbance.A cross-sectional study was conducted with children with AD ages 5 to 17 years and 1 parent (n = 61), who completed sleep, itch, and AD-specific questionnaires; clinicians assessed disease severity. All children wore actigraphy watches for a 1-week objective sleep assessment.PROMIS sleep disturbance parent proxy reliability was high (Cronbach α = 0.90) and was differentiated among Patient-Oriented Eczema Measure (POEM)-determined disease severity groups (mean ± standard deviation in mild vs moderate vs severe was 55.7 ± 7.5 vs 59.8 ± 10.8 vs 67.1 ± 9.5; P < .01). Sleep disturbance correlated with itch (numeric rating scale, r = 0.48), PROMIS sleep-related impairment (r = 0.57), and worsened quality of life (Children's Dermatology Life Quality Index, r = 0.58), with all P values less than .01. Positive report on the POEM sleep disturbance question has high sensitivity (95%) for PROMIS parent proxy-reported sleep disturbance (T-score ≥ 60). An algorithm for screening and intervening on sleep disturbance was proposed.This was a local sample.Sleep disturbance in pediatric AD should be screened using the POEM sleep question, with further assessment using the PROMIS sleep disturbance measure or objective sleep monitoring if needed.

Overview of a Sleep Monitoring Protocol for a Large Natural Population

Abstract: A standard operating procedure for studying the sleep phenotypes in a large population cohort is proposed. It is intended for academic researchers in investigating the sleep phenotypes in conjunction with the clinical sleep disorders assessment guidelines. The protocol refers to the definitive American Academy of Sleep Medicine (AASM) manual for setting polysomnography (PSG) technical specifications, scoring of sleep and associated events, etc. On this basis, it not only provides a standardized procedure of sleep interview, sleep-relevant questionnaires, and laboratory-based PSG test, but also offers a comprehensive process of sleep data analysis, phenotype extraction, and data storage. Both the objective sleep data recorded by PSG test and subjective sleep information obtained by the sleep interview and sleep questionnaires are involved in the data acquisition procedure. Subsequently, sleep phenotypes can be characterized by observable/inconspicuous physiological patterns during sleep from PSG test or can be marked by sleeping habits like sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, daytime dysfunction, etc., from sleep interview or questionnaires derived. In addition, solutions to the problems that may be encountered during the protocol are summarized and addressed. With the protocol, it can significantly improve scientific research efficiency and reduce unnecessary workload in large population cohort studies. Moreover, it is also expected to provide a valuable reference for researchers to conduct systematic sleep research.

Longitudinal Course of Sleep Disturbance and Relationship With Itch in Adult Atopic Dermatitis in Clinical Practice

Abstract: Background: Sleep disturbance (SD) is common in atopic dermatitis (AD). We examined the longitudinal course of SD and relationship with itch in AD patients. Methods: A prospective, dermatology practice-based study was performed (N = 1295) where patients were assessed at baseline and follow-up visits. Results: At baseline, 16.9% of the patients had severe SD based on Patient-Reported Outcomes Information System (PROMIS) SD T scores, 19.1% had difficulty falling asleep, 22.9% had difficulty staying asleep, and 34.2% had SD from AD. A total of 31.4% of the patients with difficulty staying asleep at baseline experienced persistent difficulties (for 3 follow-ups or more). Only 17.7% with baseline difficulty falling asleep had persistent disturbance. Despite significant fluctuation in sleep scores, SD generally improved over time. Of the patients facing baseline SD from AD, 31.5% experienced SD at the first visit, and only 12.3% experienced persistent SD at the second follow-up visit. Predictors of increased PROMIS sleep-related impairment T scores over time included baseline PROMIS sleep-related impairment T scores (0.74 [0.68-0.80]), having 3 to 6 nights of itch (2.22 [0.85-3.59]), and severe/very severe AD (4.40 [2.60-6.20]). Conclusions: A significant proportion of adult AD patients, particularly those with moderate-severe AD and frequent itch, had baseline SD. Although sleep scores generally improved over time, many patients experienced a fluctuating or persistent course.

TransSleep: Transitioning-Aware Attention-Based Deep Neural Network for Sleep Staging

Abstract: Sleep staging is essential for sleep assessment and plays a vital role as a health indicator. Many recent studies have devised various machine/deep learning methods for sleep staging. However, two key challenges hinder the practical use of those methods: 1) effectively capturing salient waveforms in sleep signals and 2) correctly classifying confusing stages in transitioning epochs. In this study, we propose a novel deep neural-network structure, TransSleep, that captures distinctive local temporal patterns and distinguishes confusing stages using two auxiliary tasks. In particular, TransSleep captures salient waveforms in sleep signals by an attention-based multiscale feature extractor and correctly classifies confusing stages in transitioning epochs, while modeling contextual relationships with two auxiliary tasks. Results show that TransSleep achieves promising performance in automatic sleep staging. The validity of TransSleep is demonstrated by its state-of-the-art performance on two publicly available datasets: 1) Sleep-EDF and 2) MASS. Furthermore, we performed ablations to analyze our results from different perspectives. Based on our overall results, we believe that TransSleep has immense potential to provide new insights into deep-learning-based sleep staging.

Wide-spread brain activation and reduced CSF flow during avian REM sleep

Abstract: Mammalian sleep has been implicated in maintaining a healthy extracellular environment in the brain. During wakefulness, neuronal activity leads to the accumulation of toxic proteins, which the glymphatic system is thought to clear by flushing cerebral spinal fluid (CSF) through the brain. In mice, this process occurs during non-rapid eye movement (NREM) sleep. In humans, ventricular CSF flow has also been shown to increase during NREM sleep, as visualized using functional magnetic resonance imaging (fMRI). The link between sleep and CSF flow has not been studied in birds before. Using fMRI of naturally sleeping pigeons, we show that REM sleep, a paradoxical state with wake-like brain activity, is accompanied by the activation of brain regions involved in processing visual information, including optic flow during flight. We further demonstrate that ventricular CSF flow increases during NREM sleep, relative to wakefulness, but drops sharply during REM sleep. Consequently, functions linked to brain activation during REM sleep might come at the expense of waste clearance during NREM sleep.

Context matters: changes in memory over a period of sleep are driven by encoding context

Abstract: During sleep, recently acquired episodic memories (i.e., autobiographical memories for specific events) are strengthened and transformed, a process termed consolidation. These memories are contextual in nature, with details of specific features interwoven with more general properties such as the time and place of the event. In this study, we hypothesized that the context in which a memory is embedded would guide the process of consolidation during sleep. To test this idea, we used a spatial memory task and considered changes in memory over a 10-h period including either sleep or wake. In both conditions, participants (N = 62) formed stories that contextually bound four objects together and then encoded the on-screen spatial position of all objects. Results showed that the changes in memory over the sleep period were correlated among contextually linked objects, whereas no such effect was identified for the wake group. These results demonstrate that context-binding plays an important role in memory consolidation during sleep.

Performance of a Convolutional Neural Network Derived From PPG Signal in Classifying Sleep Stages

Abstract: Automatic sleep stage classification is vital for evaluating the quality of sleep. Conventionally, sleep is monitored using multiple physiological sensors that are uncomfortable for long-term monitoring and require expert intervention. In this study, we propose an automatic technique for multi-stage sleep classification using photoplethysmographic (PPG) signal. We have proposed a convolutional neural network (CNN) that learns directly from the PPG signal and classifies multiple sleep stages. We developed models for two- (Wake-Sleep), three- (Wake-NREM-REM) and four- (Wake-Light sleep-Deep sleep-REM) stages of sleep classification. Our proposed approach shows an average classification accuracy of 94.4%, 94.2%, and 92.9% for two, three, and four stages, respectively. Experimental results show that the proposed CNN model outperforms existing state-of-the-art models (classical and deep learning) in the literature.

Sleep Quality in the Advanced Heart Failure ICU

Abstract: In this study, we evaluated sleep quality changes in persons with advanced heart failure (HF) who were admitted to the intensive care unit. Sleep quality was assessed at admission, during hospitalization, and post-discharge. Statistical tests compared within subject mean sleep quality over time (n = 22). Poor quality sleep was reported by 96% of participants at admission, 96% during hospitalization, and 86% post-discharge. Significant differences were found between timepoints in global sleep quality, subject sleep quality, sleep duration, and habitual sleep efficiency. A greater proportion of these participants had poor global sleep quality during hospitalization than previously reported. Participants reported better sleep post-discharge than admission and during hospitalization. Interventions enhancing hospital sleep, along with home sleep self-management education, would improve HF outcomes. Implementation science methods are warranted to integrate efficacious interventions in this population.

The Effect of Obstructive Sleep Apnea on Sleep-dependent Emotional Memory Consolidation

Abstract: Rationale: A growing body of evidence suggests that sleep is critical for the adaptive processing and consolidation of emotional information into long-term memory. Previous research has indicated that emotional components of scenes particularly benefit from sleep in healthy groups, yet sleep-dependent emotional memory processes remain unexplored in clinical cohorts, including those with obstructive sleep apnea (OSA). This line of research is important as it will add to the understanding of how disrupted sleep in OSA contributes to both impaired cognition and emotion dysregulation. Objectives: To test the hypothesis that individuals with OSA will have impaired sleep-dependent memory consolidation, with the greatest impact being on memory for emotional content. Methods: In this study, a group of newly diagnosed patients with OSA (n = 26; 10 female; average age, 42.5 years) and a matched group of healthy control subjects (n = 24; 13 female; average age, 37 years) were enrolled in the study at Beth Israel Deaconess Medical Center. Participants encoded scenes with negative or neutral foreground objects placed on neutral backgrounds before a night of polysomnographically recorded sleep. In the morning, they completed a recognition test in which old and new scene objects and backgrounds, presented separately and one at a time, were judged as old, new, or similar compared with what had been previously viewed. Results: Patients with OSA had a deficit in recognition memory for the scenes. Overall recognition (the ability to recognize old items as either old or similar) was impaired across all scene elements, both negative and neutral objects and backgrounds, whereas specific recognition (correctly identifying old items as old) was impaired only for negative objects. Across all participants, successful overall recognition correlated positively with sleep efficiency and rapid eye movement (REM) sleep, whereas successful specific memory recognition correlated only with REM sleep. Conclusions: Our findings indicate that fragmented sleep and reduced REM sleep, both hallmarks of OSA, are associated with disruptions in general memory impairment and veridical memory for emotional content, which could alter emotional regulation and contribute to comorbid emotional distress in OSA.

Work-Related Sleep Disorders: Causes and Impacts

Abstract: Abstract Insufficient sleep syndrome, shift work disorder, and obstructive sleep apnea (OSA) not only significantly impact the health of affected individuals, but also pose a threat to public safety. This article describes the clinical manifestations and impact of these sleep disorders, particularly as they pertain to workers' health and those with safety-sensitive positions. Sleep deprivation, circadian rhythm disruptions, and excessive daytime sleepiness—hallmarks of insufficient sleep, shift work disorder, and OSA, respectively—all lead to a series of cognitive deficits and impaired concentration that affect workers in a wide variety of fields. We describe the health consequences of these disorders along with treatment strategies, with a focus on current regulatory standards and the under-recognition of OSA in commercial drivers. Given its large scale, there is a need for improved guidelines and regulations for the screening, diagnosis, treatment, and long-term follow-up of OSA in commercial motor vehicle drivers. Increased recognition of the ways in which these sleep disorders impact workers will pave the way for significant improvements in occupational health and safety.

Acute sleep loss decreases CSF-to-blood clearance of Alzheimer's disease biomarkers.

Abstract: INTRODUCTION Sleep deprivation increases cerebrospinal fluid (CSF) amyloid beta (Aβ) and tau levels; however, sleep's effect on Aβ and tau in plasma is unknown. METHODS In a cross-over design, CSF Aβ and tau concentrations were measured in five cognitively normal individuals who had blood and CSF collected every 2 hours for 36 hours during sleep-deprived and normal sleep control conditions. RESULTS Aβ40, Aβ42, unphosphorylated tau threonine181 (T181), unphosphorylated tau threonine-217 (T217), and phosphorylated T181 (pT181) concentrations increased ∼35% to 55% in CSF and decreased ∼5% to 15% in plasma during sleep deprivation. CSF/plasma ratios of all Alzheimer's disease (AD) biomarkers increased during sleep deprivation while the CSF/plasma albumin ratio, a measure of blood-CSF barrier permeability, decreased. CSF and plasma Aβ42/40, pT181/T181, and pT181/Aβ42 ratios were stable longitudinally in both groups. DISCUSSION These findings show that sleep loss alters some plasma AD biomarkers by lowering brain clearance mechanisms and needs to be taken into account when interpreting individual plasma AD biomarkers but not ratios.

Mediterranean Dietary Patterns Related to Sleep Duration and Sleep-Related Problems among Adolescents: The EHDLA Study

Abstract: Purpose: The aim of the present study was to examine the association of adherence to the Mediterranean Diet (MD) and its specific components with both sleep duration and sleep-related disorders in a sample of adolescents from the Valle de Ricote (Region of Murcia, Spain). Methods: This cross-sectional study included a sample of 847 Spanish adolescents (55.3% girls) aged 12–17 years. Adherence to the MD was assessed by the Mediterranean Diet Quality Index for Children and Teenagers. Sleep duration was reported by adolescents for weekdays and weekend days separately. The BEARS (Bedtime problems, Excessive daytime sleepiness, Awakenings during the night, Regularity and duration of sleep, and Sleep-disordered breathing) screening was used to evaluate issues related to sleep, which include difficulties at bedtime, excessive drowsiness during the day, waking up frequently during the night, irregularity, length of sleep, and breathing issues while sleeping. Results: Adolescents who presented a high adherence to the MD were more likely to meet the sleep recommendations (OR = 1.52, 95% CI 1.12–2.06, p = 0.008) and less likely to report at least one sleep-related problem (OR = 0.56, 95% CI 0.43–0.72, p < 0.001). These findings remained significant after adjusting for sex, age, socioeconomic status, waist circumference, energy intake, physical activity, and sedentary behavior, indicating a significant association of adherence to the MD with sleep outcomes (meeting sleep recommendations: OR = 1.40, 95% CI 1.00–1.96, p = 0.050; sleep-related problems: OR = 0.68, 95% CI 0.50–0.92, p = 0.012). Conclusions: Adolescents with high adherence to the MD were more likely to report optimal sleep duration and fewer sleep-related problems. This association was more clearly observed for specific MD components, such as fruits, pulses, fish, having breakfast, dairies, sweets, and baked goods/pastries.

Measuring Light Regularity: Sleep Regularity is Associated with Regularity of Light Exposure in Adolescents.

Abstract: STUDY OBJECTIVES Light is the main time cue for the human circadian system. Sleep and light are intrinsically linked; irregular light patterns can influence sleep patterns and sleep can influence light exposure patterns. However, metrics for quantifying light regularity are lacking, and the relationship between sleep and light regularity is under-explored. We developed new metrics for light regularity and demonstrated their utility in adolescents, across school term and vacation. METHODS Daily sleep/wake and light patterns were measured using wrist actigraphy in 75 adolescents (54% male, 17.17±0.83 years) over two weeks of school term and a subsequent two-week vacation. The Sleep Regularity Index (SRI) and Social Jetlag were computed for each two-week block. Light regularity was assessed using (i) variation in mean daily light timing (MLiT); (ii) variation in daily photoperiod; and (iii) the Light Regularity Index (LRI). Associations between SRI and each light regularity metric were examined, and within-individual changes in metrics were examined between school and vacation. RESULTS Higher SRI was significantly associated with more regular LRI scores during both school and vacation. There were no significant associations of SRI with variation in MLiT or daily photoperiod. Compared to school term, all three light regularity metrics were less variable during the vacation. CONCLUSIONS Light regularity is a multi-dimensional construct, which until now has not been formally defined. Irregular sleep patterns are associated with lower LRI, indicating that irregular sleepers also have irregular light inputs to the circadian system, which likely contributes to circadian disruption.

Sleep disturbance in post COVID-19 conditions: Prevalence and quality of life

Abstract: Post COVID-19 conditions are complaints and symptoms in patients with a history of probable or confirmed COVID-19 after 3 months of the onset of COVID-19 and last at least 2 months. About 10–20% of people may experience post COVID-19 conditions, one of which is sleep disturbance. There is a wide range of prevalence of sleep disturbances from 6% to more than 70%. An online survey of the post COVID-19 conditions in various countries showed that 78.58% of subjects had sleep disturbances, including insomnia, sleep-disordered breathing, central disorders of hypersomnolence, circadian rhythm sleep-wake disorders, parasomnias, and sleep-related movement disorders. Sleep disturbance can be found starting from 2 weeks until 48 weeks or more after discharge or after having a negative COVID-19 test results. Women aged < 50 years old with severe COVID-19 infection reported a worse outcome. Several mechanisms may cause sleep disturbance in post COVID-19 condition, namely persistent viral infection and inflammation, immunity dysregulation, and mitochondrial dysfunction. Several studies discovered sleep disturbance was a major problem that affected different domains of QoL in post COVID-19 conditions. Significant correlation was found between several dimensions of SF-36 with moderate-to-severe insomnia in post COVID-19 conditions. Therefore, sleep disturbance is a major problem in post COVID-19 conditions and may affect patients' QoL, and the existence of sleep disturbance should be a concern in post COVID-19 conditions period. Further research is required to determine the prevalence based on agreed definition as well as methods to assess this condition and its impact on QoL.

Dysfunction of circadian and sleep rhythms in the early stages of Alzheimer's disease

Abstract: Dysfunction of circadian and sleep rhythms is an early feature of many neurodegenerative diseases. Alzheimer's disease (AD) is a progressive neurodegenerative disorder resulting in cognitive and psychiatric disturbances. Although it is largely unclear whether dysfunctions in sleep and circadian rhythms contribute to the etiology of AD or are a consequence of the disease, there is evidence that these conditions are involved in a complex self‐reinforcing bidirectional relationship. According to the recent studies, dysregulation of the circadian clock already occurs during the asymptomatic stage of the disease and could promote neurodegeneration. Thus, restoration of sleep and circadian rhythms in preclinical AD may represent an opportunity for early intervention to slow the disease course.