Functions and Mechanisms of Sleep

The regulation of glutamatergic nervous system in sleep-wake states and general anesthesia

The sleep-wake states and general anesthesia share many neurophysiological similarities, as both involve reversible changes in consciousness and modulation of brain activity. This paper reviews the role of glutamatergic neurons, the brain's primary excitatory neurons, in regulating sleep-wake states and general anesthesia. We discuss the involvement of glutamatergic neurons across various brain regions, including the brainstem, basal forebrain, thalamus, hypothalamus, and cortex, highlighting their contributions to physiological sleep-wake and anesthesia modulation. Recent advancements in techniques such as optogenetics, chemogenetics, and neural tracing have enhanced our understanding of these neurons' functions. Understanding these mechanisms can lead to improved therapeutic strategies for sleep disorders and more precise anesthetic practices, providing new avenues for clinical intervention.

Associations between sleep, energy balance, and obesity markers over 6 months in Black emerging adults-pilot study findings from the Sleep, Health Outcomes, and Body Weight (SHOW) study

Insufficient sleep (short sleep duration and poor sleep quality) is associated with obesity risk. Emerging adults (ages 18-28 years) have a greater risk of excess weight gain and insufficient sleep, and these risks are higher in Black individuals. Using a measurement burst design, we assessed associations between sleep with energy balance components and obesity marker changes over 6 months in 15 Black emerging adults (12 females; age: 21 ± 2.5 years; body mass index: 25.7 ± 4.5 kg/m2; body fat: 25.8 ± 11.9%). Since our sample was predominantly female (80%), we repeated our analyses for females only. Participants completed the following measurements at baseline (BLN) and 6 months later (6MO): 7 days of actigraphy-based sleep and physical activity energy expenditure (EE) and 2 nights of in-home polysomnography-based sleep; resting EE and thermic effect of food with indirect calorimetry; ad libitum energy intake (EI) via self-reported methods over 4 days and directly measured over 3 days with provided meals. Body weight (2.6 kg, p = 0.01) and waist circumference (2.4 cm, p = 0.03) increased from BLN to 6MO. Changes in actigraphy-based sleep duration were associated with changes in body weight (β = 0.03, standard error (SE) = 0.02, p = 0.04) and fat mass (β = 0.07, SE = 0.03 p = 0.03) in females only. Greater rapid eye movement sleep duration was associated with increases in resting EE (β = 2.24, SE = 0.84, p = 0.02). Greater slow-wave sleep was associated with increases in self-reported EI (β = 18.34, SE = 4.7, p < 0.01). Sleep may impact components of energy balance and risk of weight gain in Black emerging adults. Additional research is needed to confirm our pilot findings.

Bilingualism, sleep, and cognition: An integrative view and open research questions

Sleep and language are fundamental to human existence and have both been shown to substantially affect cognitive functioning including memory, attentional performance, and cognitive control. Surprisingly, there is little-to-no research that examines the shared impact of bilingualism and sleep on cognitive functions. In this paper, we provide a general overview of existing research on the interplay between bilingualism and sleep with a specific focus on executive functioning. First, we highlight their interconnections and the resulting implications for cognitive performance. Second, we emphasize the need to explore how bilingualism and sleep intersect at cognitive and neural levels, offering insights into potential ways of studying the interplay between sleep, language learning, and bilingual language use. Finally, we suggest that understanding these relationships could enhance our knowledge of reserve and its role in mitigating age-related cognitive decline.

Sleep quality and disruptive nocturnal behaviors as short-term predictors of suicidal intent: An ecological momentary assessment study

BACKGROUND

Emerging research suggests that poor sleep quality and some disruptive nocturnal behaviors (DNBs) may be advance markers of short-term worsening in suicidal intent. However, relationships between many types of DNBs and suicide risk have not been examined, and whether DNBs provide useful information apart from sleep quality in predicting suicidal intent is unknown. This study addressed these critical knowledge gaps by examining associations between sleep quality, DNBs, and next-day suicidal intent in a community sample of adults.

METHODS

A sample of 237 adults with severe suicidal ideation provided daily indices of sleep quality and DNBs, and suicidal intent 6 times per day for 2 weeks via ecological momentary assessment. Linear mixed models and general linear models were conducted to examine relationships between sleep quality and DNBs with measures of average severity of suicidal intent and fluctuations in intent over time.

RESULTS

Poor sleep quality and specific DNBs (sleep disruptions due to general nervousness, trauma-related memories and/or nightmares interrupting sleep, and non-trauma-related anxiety or panic) predicted more severe suicidal intent in multivariate models. Only poor sleep quality predicted within-day variability in suicidal intent.

CONCLUSIONS

These findings suggest that monitoring sleep quality and specific DNBs may be a useful indicator of short-term risk for worsening in suicidal intent.

Microbiome-Based Therapeutics for Insomnia

Insomnia poses considerable risks to both physical and mental health, leading to cognitive impairment, weakened immune function, metabolic dysfunction, cardiovascular issues, and reduced quality of life. Given the significant global increase in insomnia and the growing scientific evidence connecting gut microbiota to this disorder, targeting gut microbiota as an intervention for insomnia has gained popularity. In this review, we summarize current microbiome-based therapeutics for insomnia, including dietary modifications; probiotic, prebiotic, postbiotic, and synbiotic interventions; and fecal microbiota transplantation. Moreover, we assess the capabilities and weaknesses of these technologies to offer valuable insights for future studies.

Relationship Between Sleep Disturbances and Chronic Pain: A Narrative Review

Sleep disturbances and chronic pain are prevalent and interrelated conditions that have significant impact on individuals' quality of life. Understanding the intricate dynamics between sleep and pain is crucial for developing effective treatments that enhance the well-being of affected individuals and reduce the economic burden of these debilitating conditions. This narrative review examines the complex relationship between sleep disturbances and chronic pain. We describe the prevalence and types of sleep disturbances and sleep disorders in chronic pain patients. Posteriorly, we critically review the clinical and experimental evidence, investigating the relationship between sleep disturbances and chronic pain, aiming to clarify the impact of chronic pain on sleep and, conversely, the impact of sleep disturbances on pain perception. In conclusion, the literature largely agrees on the existence of a bidirectional relationship between chronic pain and sleep disturbances, though the strength of each direction in this association remains uncertain. Current evidence suggests that sleep impairment more strongly predicts pain than pain does sleep impairment. Additionally, addressing sleep disturbances in chronic pain patients is crucial, as poor sleep has been linked to higher levels of disability, depression, and pain-related catastrophizing.

Associations of seasonally available global positioning systems-derived walkability and objectively measured sleep in the Nurses' Health Study 3 Mobile Health Substudy

Background

Sleep is influenced by the environments that we experience while awake and while asleep. Neighborhood walkability has been linked with chronic disease and lifestyle factors, such as physical activity; however, evidence for the association between walkability and sleep is mixed. Extant studies assign walkability based on residential addresses, which does not account for mobility. We examined the association between walkability and sleep in the Nurses' Health Study 3 (NHS3) Mobile Health Substudy (MHS).

Methods

From 2018 to 2020, individuals in the United States-based NHS3 prospective cohort participated in the MHS, in which minute-level global positioning systems (GPS) data and objective sleep duration and efficiency measures were collected via a custom smartphone application and Fitbit, respectively, for four 7-day periods across a year to capture seasonal variability. Census tract walkability was calculated by summing z-scores of population density (2015-2019 American Community Survey), business density (2018 Infogroup), and intersection density (2018 TIGER/Line road shapefiles). We ran generalized additive mixed models with penalized splines to estimate the association between walkability and sleep, adjusting for individual-level covariates as well as GPS-based exposure to environmental and contextual factors.

Results

The average main sleep period duration was 7.9 hours and the mean sleep efficiency was 93%. For both sleep duration and sleep efficiency, we did not observe an association with daily average walkability exposure.

Conclusion

In this study of women across the United States, we found that daily GPS-based neighborhood walkability exposure during wake time was not associated with objective wearable-derived sleep duration or sleep efficiency.

Key actors in neuropathophysiology: The role of γδ T cells

The neuroimmune axis has been the focus of many studies, with special emphasis on the interactions between the central nervous system and the different immune cell subsets. T cells are namely recognized to play a critical role due to their interaction with nerves, by secreting cytokines and neurotrophins, which regulate the development, function, and survival of neurons. In this context, γδ T cells are particularly relevant, as they colonize specific tissues, namely the meninges, and have a wide variety of complex functions that balance physiological systems. Notably, γδ T cells are not only key components for maintaining brain homeostasis but are also responsible for triggering or preventing inflammatory responses in various pathologies, including neurodegenerative diseases as well as neuropsychiatric and developmental disorders. Here, we provide an overview of the current state of the art on the contribution of γδ T cells in neuropathophysiology and delve into the molecular mechanisms behind it. We aim to shed light on γδ T cell functions in the central nervous system while highlighting upcoming challenges in the field and providing new clues for potential therapeutic strategies.

The relationship between sleep duration and physical activity level among Norwegian adolescents: a cross-sectional study

Background

Failure to adhere to sleep and physical activity recommendations among adolescents constitutes a public health problem. However, the associations between sleep duration and adolescents' physical activity levels remain less explored. The aims of this paper were twofold: (1) to describe sleep and physical activity levels among Norwegian school-based adolescents, stratified by school level and sex and (2) to explore the association between sleep and physical activity levels.

Methods

Data were derived from the 2022 Norwegian Ungdata Survey, totaling 63,113 adolescents from lower (aged 13 to 16 years) and upper (aged 16 to 19 years) secondary schools. Study variables were measured using single-item questions from the Ungdata survey and collected through an electronic questionnaire administered during school hours. Logistic regressions were performed using crude analysis and adjusted for Socioeconomic status (SES) and grade level (age).

Results

In lower secondary school, 57.0% of girls and 44.7% of boys reported sleeping less than the recommended 8 h, whereas in upper secondary school, the rate was 74.9% among girls and 74.3% among boys. Girls consistently reported more sleep problems, feeling more tired at school or during activities, and less physical activity than boys across school levels. Sleep duration was a significant predictor for all levels of weekly physical activity among girls across school levels, with the highest odds revealed in upper secondary school among those being active 5 times a week (B = 1.32; 95% CI [1.24 to 1.40]). Sleep duration was a predictor for being active 5 times a week for boys across school levels (B = 1.22; 95% CI [1.17 to 1.27]).

Conclusion

About half of younger adolescents and three-quarters of older adolescents do not adhere to the sleep recommendation. Lower levels of physical activity were consistently reported by girls than boys. Sleep duration consistently predicted a 20 to 30% higher likelihood of being active at least 5 days a week across sex and school levels. These findings underscore the critical role of sleep duration relations to higher physical activity levels among Norwegian adolescents. Government and policymakers should encourage healthy sleep and PA habits by explicitly incorporating guidelines into the curriculum.

Four SpsP neurons are an integrating sleep regulation hub in Drosophila

Sleep is essential and highly conserved, yet its regulatory mechanisms remain largely unknown. To identify sleep drive neurons, we imaged Drosophila brains with calcium-modulated photoactivatable ratiometric integrator (CaMPARI). The results indicate that the activity of the protocerebral bridge (PB) correlates with sleep drive. We further identified a key three-layer PB circuit, EPG-SpsP-PEcG, in which the four SpsP neurons in the PB respond to ellipsoid body (EB) signals from EPG neurons and send signals back to the EB through PEcG neurons. This circuit is strengthened by sleep deprivation, indicating a plasticity response to sleep drive. SpsP neurons also receive inputs from the sensorimotor brain region, suggesting that they may encode sleep drive by integrating sensorimotor and navigation cues. Together, our experiments show that the four SpsP neurons and their sleep regulatory circuit play an important and dynamic role in sleep regulation.

Causal relationship between sleep characteristics and thyroid function: A bidirectional Mendelian randomization study

BACKGROUND

Previous researches have revealed some links between thyroid function and sleep characteristics, however it remains unclear which one causes the other. The purpose of this study was to investigate the potential causal relationship between hyperthyroidism, hypothyroidism, and sleep characteristics.

METHODS

We utilized aggregated data from published genome-wide association studies (GWAS) to select genetic instruments for sleep variables. The 5 sleep-related traits (chronotype, short sleep duration, long sleep duration, daytime sleepiness, and insomnia) were associated with distinct genetic variants chosen as instrumental factors. Employing MR Egger's analysis of Mendelian randomization (MR), weighted median, weighted mode, and inverse variance weighted (IVW) methods to assess the 5 sleep traits in relation to hyperthyroidism and hypothyroidism, we subsequently conducted inverse MR analysis to examine the causal relationship between thyroid function and the 5 sleep characteristics.

RESULTS

The IVW technique did not reveal a causal association between chronotype, short sleep duration, long sleep duration, daytime sleepiness, or insomnia and the risk of abnormal thyroid function in the study investigating the influence of sleep characteristics on this risk. The outcomes of the IVW approach were consistent with the remaining 3 methods. The IVW, weighted median, MR Egger, and weighted mode methods in the reverse magnetic resonance imaging investigation did not yield evidence of a causative association between the risk of time type, long sleep duration, and insomnia and abnormal thyroid function. In contrast, the weighted median and weighted mode methods showed a possible causal relationship between hypothyroidism and short sleep duration and daytime sleepiness. Sensitivity analyses showed that the results were robust and no pleiotropy or heterogeneity was detected.

CONCLUSION

More precisely, our analysis did not uncover any indication of a reciprocal causal link between thyroid function and genetically predicted sleep characteristics.

Assessment of Sleep Quality in Adolescents with Overweight and Obesity Using the Adolescent Sleep Hygiene Scale (ASHS)

BACKGROUND

Adolescent overweight and obesity are a public health problem with an epidemic trend. There is growing evidence that sleep quality correlates to body weight. The aim of this study was to investigate, sleep quality in adolescents with obesity/overweight.

METHODS

A total of 100 adolescents with overweight/obesity aged 12-18 years were enrolled. Anthropometric parameters were recorded and a laboratory investigation in the fasting state [glucose, insulin, cholesterol (TC), high-density lipoprotein cholesterol (HDL), low-density lipoprotein cholesterol (LDL), triglycerides, uric acid and glycated hemoglobin (HbA1c)] was performed. Insulin resistance was calculated by the Homeostasis Model Assessment of Insulin Resistance index (HOMA-IR). Sleep quality was assessed with the Adolescent Sleep Hygiene Scale (ASHS) questionnaire.

RESULTS

According to ASHS, 93% of the participants were classified as "Good Sleepers" (GSs) (score > 3.8) and 7% as "Poor Sleepers" (PSs) (score < 3.8). PSs had a statistically higher body mass index (BMI) compared to GSs (p = 0.026). Increased body mass index (BMI) (r = -0.306, p = 0.002), fast insulin (r = -0.224, p = 0.027), and HOMA-IR (r = -0.260, p = 0.010) exerted a negative effect on sleep quality. Controlling for lipids and uric acid, only TC levels appeared to have a statistically significant and specifically positive correlation with the ASHS score (r = 0.202, p = 0.045). HbA1c values and waist circumference tended to be negatively correlated, but not significant to adolescent sleep quality [(r = -0.101, p = 0.330), (r = -0.095, p = 0.359), respectively]. The influence of central obesity on the ASHS score was also explored, but no correlation was found (p = 0.566).

CONCLUSIONS

Sleep quality, as reflected by the ASHS score, was associated negatively with BMI, fasting insulin levels, and insulin resistance. Furthermore, a gender difference was observed, as adolescent males were found to achieve a higher overall ASHS score compared to females.

Association between sleep quality, sleep duration, and physical frailty among adults aged 50 years and older in India

BACKGROUND

Considering the significant growth in India's aging population, it is imperative to identify factors associated with frailty among older Indians. This study examined the association between sleep quality, sleep duration, and physical frailty among older adults in India. Moreover, we examined whether the associations between sleep quality, sleep duration, and physical frailty varied by gender.

METHODS

In this secondary analysis, we used data from the 2015 wave 2 of the Study on Global Aging and Adult Health (WHO-SAGE) in India, comprising a sample of 6,512 older adults aged 50 years and above. Pre-frailty and frailty were assessed using the modified version of the frailty phenotype developed by Fried and colleagues. Sleep was assessed by self-reported quality and duration. Multinomial and multivariable logistic regression models were used to examine the associations between sleep quality, sleep duration, and physical frailty (including its components), as well as to explore the moderating effect of gender.

RESULTS

66.8% of older Indians were pre-frail, while 25.2% were frail. Relative to those with good sleep quality, older adults with poor sleep quality had significantly higher odds of frailty [AOR: 2.79; CI: 1.37-5.66]. Compared to those receiving the recommended age-appropriate 7-8 h of sleep, older adults sleeping ≥ 9 h reported a significantly lower likelihood of both pre-frailty [AOR: 0.73; CI: 0.57-0.93] and frailty [AOR: 0.68; CI: 0.51-0.91]. Analysis of specific components of frailty showed that older adults with long sleep had lower odds of exhaustion [AOR: 0.86; CI: 0.73-1.00] compared to those with age-appropriate sleep duration. Moreover, frailty was more pronounced in older men with poor sleep quality and short sleep duration (< 7 h/night) than in older women with similar sleep patterns. Poor sleep quality was not linked to any of the frailty components in older women; however, in older men, it was associated with exhaustion [AOR: 4.28; CI: 2.28-8.06], weak grip strength [AOR: 2.31; CI: 1.46-3.67], and low physical activity [AOR: 2.81; CI: 1.10-7.21].

CONCLUSION

The findings indicate potential associations between sleep quality, sleep quantity, and physical frailty among older Indians. Poor sleep quality was associated with frailty, yet long sleep duration was associated with a lower prevalence of frailty, independent of sleep quality. Moreover, the prevalence of frailty associated with poor sleep quality and shorter sleep duration was more pronounced among older Indian men than women, underscoring the need for targeted interventions to address sleep-related concerns in this demographic.

Prevalence and Correlates of Poor Sleep Quality Among Psychiatry Physicians in Saudi Arabia: A Cross-Sectional Study

Background and Aims

Sleep issues pose a significant burden to public health and well-being in Saudi Arabia. However, research evidence on sleep health among psychiatry physicians in this territory is limited. Therefore, to bridge the research gap, this study was designed to assess the prevalence and predictors of poor sleep quality among psychiatry physicians in the country.

Methods

This cross-sectional study included 554 psychiatry physicians in Saudi Arabia from March to August 2023. Data were collected via online through a structured questionnaire (Google survey form). Sleep quality, the outcome variable of our study, was evaluated with the Pittsburgh Sleep Quality Index (PSQI; 19 items). Independent variables included sociodemographic and behavioral characteristics, sleep habits, major depression (assessed with Patient Health Questionnaire-9), and anxiety (measured with Generalized Anxiety Disorder-7) symptoms. Binary logistic regression analysis was performed to identify the correlates of poor sleep quality.

Results

Based on the PSQI, 61.3% of the study participants had poor-quality sleep (age range: 24-56 years, male: 48.0%). The adjusted model revealed that male participants (AOR = 2.80, 95% CI = 1.70-4.61) and those who had on-call duties ≥ 2 times per week (for three/four per week: AOR = 3.41, 95% CI = 1.89-6.14) were at higher risk of developing poor sleep quality compared to their respective counterparts. Participants with depressive symptoms (AOR = 3.46, 95% CI = 1.60-7.48) and smoking habits (AOR = 3.47, 95% CI = 1.32-9.08) had higher odds of developing poor sleep quality than their counterparts. Moreover, participants who always used their smartphone/laptop before going to bed were more likely to have poor sleep quality than those who never used such (AOR = 3.15, 95% CI = 1.31-7.60).

Conclusion

Poor sleep quality is extremely prominent among psychiatry physicians in Saudi Arabia. Male sex, higher on-call duty, smoking habits, depression, and smartphone/laptop use before bedtime were significantly associated with poor sleep quality. These findings emphasize the need for sleep-health promotion interventions for Saudi psychiatry physicians.

Sleep problems and executive dysfunctions in pre-school children

AIM

The aim of the study was to examine the relationship between sleep problems and executive functions in pre-school children as reported by parents/caregivers.

METHODS

This cross-sectional study of caregiver-child dyads was conducted in a public kindergarten school in Northern Thailand. Sleep problems were evaluated using the Children's Sleep Habits Questionnaire (CSHQ), whereas executive functions were assessed using the Behavioural Rating Inventory of Executive Function - pre-school version (BRIEF-P). T-scores greater than 65 of the BRIEF-P were defined as deficits in executive functions. Multiple linear regressions were performed to assess the association between the executive function components and the total CSHQ scores.

RESULTS

Participants included 356 children, with a mean age of 5.04 (0.54) years. The total CSHQ scores of the executive dysfunction group were significantly higher than those of the group with executive functions below the cutoff (P < 0.001), which indicated more of sleep problems, including sleep-onset delay, night waking and daytime sleepiness. However, the duration of night sleep, night awake, afternoon nap and total sleep time reported by parents did not differ between the two groups. Weak positive correlations between the total CSHQ and subscale scores and the Global Executive Composite score of the BRIEF-P were noted. After adjusting for confounding variables, including child's age, gender, prematurity, maternal age and education, family income and media viewing time from the multiple linear regression analysis, the total CSHQ scores were significantly correlated with worse Global Executive Composite scores, which is the summary of five domains of executive functions (P < 0.001).

CONCLUSIONS

This study highlights the association between sleep problems and deficits in executive functions in healthy pre-school children. Health-care providers are encouraged to consistently advocate for proper sleep hygiene and practices to enhance executive functions in pre-schoolers.

Safe limits on work hours for the nursing profession: a rapid evidence review

Persistent staffing shortages in health care driven by years of inadequate funding and deficiencies in human resources planning, which overlooked the impacts of population aging, have converged into a crisis in health care settings. An essential consequence of the widespread and growing staffing shortfalls in health care has been increased pressure on nurses to work longer hours. The present rapid review has two major objectives: (1) to systematically review and synthesize evidence considering the health and human consequences of excessive work hours, work-related fatigue and associated occupational health and safety hazards; and, (2) to identify policies and practices that demonstrate efficacy in managing or mitigating the adverse effects of occupational fatigue. Findings show that shifts lasting longer than 12 h elevate the risk of occupational fatigue, leading to several fatigue-based hazards. Despite governmental restrictions on long work hours and occupational fatigue in safety-critical industries such as transport, aviation, and nuclear sectors, health care remains largely unregulated in this regard. Ensuring safe and high-quality care over the long term requires implementing adequate regulatory supports for work hour limits for nurses. These measures not only improve workplace satisfaction but also enhance patient outcomes, ultimately fostering a healthier and more resilient health care system.

Exploring the pathogenesis of insomnia and acupuncture intervention strategies based on the microbiota-gut-brain axis

Insomnia is a common sleep disorder observed in clinical settings, with a globally rising prevalence rate. It not only impairs sleep quality and daytime functioning but also contributes to a range of physiological and psychological conditions, often co-occurring with somatic and mental disorders. Currently, the pathophysiology of this condition is not fully understood. Treatment primarily involves symptomatic management with benzodiazepine receptor agonists, melatonin and its receptor agonists, sedative antidepressants, atypical antipsychotics, and orexin receptor antagonists. However, due to the adverse side effects of these drugs, including dependency, addiction, and tolerance, there is an urgent need for safer, more effective, and environmentally friendly treatment methods. In recent years, research on the microbiota-gut-brain axis has received significant attention and is expected to be key in uncovering the pathogenesis of insomnia. Acupuncture stimulates acupoints, activating the body's intrinsic regulatory abilities and exerting multi-pathway, multi-target regulatory effects. A substantial body of evidence-based research indicates that acupuncture is effective in treating insomnia. However, the unclear mechanisms of its action have limited its further clinical application in insomnia treatment. Therefore, this study aims to elucidate the pathogenesis of insomnia from the perspective of the microbiota-gut-brain axis by examining metabolic, neuro-endocrine, autonomic nervous, and immune pathways. Additionally, this study discusses the comprehensive application of acupuncture in treating insomnia, aiming to provide new strategies for its treatment.

Causal relationship between insomnia and thyroid disease: A bidirectional Mendelian randomization study

OBJECTIVE

Some correlations between thyroid disorders and insomnia have been found in previous studies; however, the causal relationship between them is unclear. The aim of this study was to investigate the causal relationship between insomnia and five thyroid disorders (hyperthyroidism, hypothyroidism, thyroiditis, thyroid nodules, and thyroid cancer).

METHODS

We assessed the causal relationship between insomnia and thyroid disorders using inverse variance weighted, weighted median, and Mendelian randomization (MR)-Egger analyses in MR analyses and then used inverse MR analyses to assess the causal relationship between thyroid disorders and insomnia.

RESULTS

MR analysis showed that insomnia did not increase the risk of hyperthyroidism, hypothyroidism, thyroiditis, thyroid nodules, and thyroid cancer. However, reverse MR analysis showed that thyroid cancer increased the risk of insomnia (OR = 1.01, 95%CI: 1.00-1.02, p = .01), and the other four thyroid disorders had no direct causal relationship with insomnia. Sensitivity analyses indicated that the results were robust and no pleiotropy or heterogeneity was detected.

CONCLUSION

This study did not find evidence of a bidirectional causal relationship between genetically predicted insomnia and hyperthyroidism, hypothyroidism, thyroiditis, and thyroid nodules. However, we found that although insomnia does not increase the risk of thyroid cancer, thyroid cancer does increase the risk of insomnia.

The effects of ketogenic dietary therapies on sleep: A scoping review

Sleep problems are common in neurological conditions for which ketogenic dietary therapies (KDTs) are recognised as an effective intervention (drug-resistant epilepsy, autism spectrum disorder, and migraine). Given the composite framework of action of ketogenic dietary therapies, the prevalence of sleep disturbance, and the importance of sleep regulation, the present scoping review aimed at identifying and mapping available evidence of the effects of ketogenic dietary therapies on sleep. A comprehensive web-based literature search was performed retrieving publications published to June 2023 using PubMed and Scopus, yielding to 277 records. Twenty papers were finally selected and included in the review. Data were abstracted by independent coders. High variability was identified in study design and sleep outcome evaluation among the selected studies. Several changes in sleep quality and sleep structure under ketogenic dietary therapies were found, namely an improvement of overall sleep quality, improvement in the difficulty falling asleep and nighttime awakenings, improvement in daytime sleepiness and an increase of REM sleep. The relevance and possible physiological explanations of these changes, clinical recommendations, and future directions in the field are discussed.

How are poor sleepers with other clinical conditions affected by maladaptive personality traits? A neural network-based analysis

Background

Psychopathology research mainly focused on the cross-sectional and longitudinal associations between personality and psychiatric disorders without considering the moment-to-moment dynamics of personality in response to environmental situations. The present study aimed to both cluster a young sample according to three mixed clinical conditions (poor sleep quality, depression, and somatization) and to predict the derived clusters by maladaptive personality traits and sex differences using a deep machine learning approach.

Methods

A sample of 839 adults aged 18-40 years (64% female) from the west of Iran were clustered according to the mixed clinical conditions using the cluster analysis techniques. An Artificial Neural Network (ANN) modeling is used to predict the derived clusters by maladaptive personality traits and biological gender. A receiver operating characteristic (ROC) curve was used to identify independent variables with high sensitivity specific to the derived clusters.

Results

The cluster analysis techniques suggested a fully stable and acceptable four-cluster solution for Depressed Poor Sleepers, Nonclinical Good Sleepers, Subclinical Poor Sleepers, and Clinical Poor Sleepers. The ANN model led to the identification of one hidden layer with two hidden units. The results of Area under the ROC Curve were relatively to completely acceptable, ranging from.726 to.855. Anhedonia, perceptual dysregulation, depressivity, anxiousness, and unusual beliefs are the most valuable traits with importance higher than 70%.

Conclusion

The machine learning approach can be well used to predict mixed clinical conditions by maladaptive personality traits. Future research can test the complexity of normal personality traits connected to mixed clinical conditions.

The Complex Relationship between Sleep and Cognitive Reserve: A Narrative Review Based on Human Studies

Sleep and brain/cognitive/neural reserve significantly impact well-being and cognition throughout life. This review aims to explore the intricate relationship between such factors, with reference to their effects on human cognitive functions. The specific goal is to understand the bidirectional influence that sleep and reserve exert on each other. Up to 6 February 2024, a methodical search of the literature was conducted using the PubMed database with terms related to brain, cognitive or neural reserve, and healthy or disturbed sleep. Based on the inclusion criteria, 11 articles were selected and analyzed for this review. The articles focus almost exclusively on cognitive reserve, with no explicit connection between sleep and brain or neural reserve. The results evidence sleep's role as a builder of cognitive reserve and cognitive reserve's role as a moderator in the effects of physiological and pathological sleep on cognitive functions. In conclusion, the findings of the present review support the notion that both sleep and cognitive reserve are critical factors in cognitive functioning. Deepening comprehension of the interactions between them is essential for devising strategies to enhance brain health and resilience against age- and pathology-related conditions.

A randomized clinical trial for a self-guided sleep intervention following moderate-severe traumatic brain injury: Study protocol

BACKGROUND

Individuals with a history of moderate-severe traumatic brain injury (TBI) experience a significantly higher prevalence of insomnia compared to the general population. While individuals living with TBI have been shown to benefit from traditional insomnia interventions (e.g., face-to-face [F2F]), such as Cognitive Behavioral Therapy for Insomnia (CBTI), many barriers exist that limit access to F2F evidence-based treatments. Although computerized CBT-I (CCBT-I) is efficacious in terms of reducing insomnia symptoms, individuals with moderate-severe TBI may require support to engage in such treatment. Here we describe the rationale, design, and methods of a randomized controlled trial (RCT) assessing the efficacy of a guided CCBT-I program for reducing insomnia symptoms for participants with a history of moderate-severe TBI.

METHODS

This is an RCT of a guided CCBT-I intervention for individuals with a history of moderate-severe TBI and insomnia. The primary outcome is self-reported insomnia severity, pre- to post-intervention. Exploratory outcomes include changes in sleep misperception following CCBT-I and describing the nature of guidance needed by the Study Clinician during the intervention.

CONCLUSION

This study represents an innovative approach to facilitating broader engagement with an evidence-based online treatment for insomnia among those with a history of moderate-severe TBI. Findings will provide evidence for the level and nature of support needed to implement guided CCBT-I. Should findings be positive, this study would provide support for a strategy by which to deliver guided CCBT-I to individuals with a history of moderate-severe TBI.

Poor sleep quality and associated factors among healthcare professionals at the University of Gondar Comprehensive Specialized Hospital, Northwest Ethiopia

Background

Poor sleep quality is linked to physiological dysfunction, which increases the risk of obesity, cardiovascular disease, cognitive impairment, and other medical conditions. Despite the known health risks of sleep disturbances, literature is still scant regarding sleep quality and its associated factors among healthcare professionals in Ethiopia. Therefore, this study aimed to determine the prevalence of poor sleep quality and its associated factors among healthcare professionals at the University of Gondar Comprehensive Specialized Hospital.

Methods

An institution-based cross-sectional study was conducted at the University of Gondar Comprehensive Specialized Hospital, Northwest Ethiopia. A total of 418 healthcare professionals participated in the study. The study participants were chosen using the stratified random sampling method. Data were collected using a structured, self-administered questionnaire. The Pittsburgh Sleep Quality Index (PSQI) was used to assess the sleep quality of participants. Bi-variable and multivariable logistic regression models were used. p ≤ 0.05 was used to declare statistically significant variables.

Results

The mean age of the study participants was 30.7 years (SD ± 6.3). The overall prevalence of poor sleep quality was 58.9% [95% CI (54.2, 63.6%)]. Being female [adjusted odds ratio (AOR) = 1.9, 95% CI (1.2, 2.9)], being a shift worker [AOR = 5.7, 95% CI (2.3, 14.3), not performing regular exercise [AOR = 2.08 (1.2-3.6)], being a khat chewer [AOR = 3.1, 95% CI (1.2, 7.6)], and having depressive symptoms [AOR = 2.6, 95% CI (1.3, 6.8)] were significantly associated with higher odds of having poor sleep quality.

Conclusion

The prevalence of poor sleep quality among healthcare professionals was found to be high. As a result, we recommend that healthcare providers at the University of Gondar Comprehensive Specialized Hospital focus on early regular screening for sleep disturbances and pay special attention to shift work schedules and behaviors such as khat chewing, exercise, and depressive symptoms.

Autophagy in Its (Proper) Context: Molecular Basis, Biological Relevance, Pharmacological Modulation, and Lifestyle Medicine

Autophagy plays a critical role in maintaining cellular homeostasis and responding to various stress conditions by the degradation of intracellular components. In this narrative review, we provide a comprehensive overview of autophagy's cellular and molecular basis, biological significance, pharmacological modulation, and its relevance in lifestyle medicine. We delve into the intricate molecular mechanisms that govern autophagy, including macroautophagy, microautophagy and chaperone-mediated autophagy. Moreover, we highlight the biological significance of autophagy in aging, immunity, metabolism, apoptosis, tissue differentiation and systemic diseases, such as neurodegenerative or cardiovascular diseases and cancer. We also discuss the latest advancements in pharmacological modulation of autophagy and their potential implications in clinical settings. Finally, we explore the intimate connection between lifestyle factors and autophagy, emphasizing how nutrition, exercise, sleep patterns and environmental factors can significantly impact the autophagic process. The integration of lifestyle medicine into autophagy research opens new avenues for promoting health and longevity through personalized interventions.

Sleep loss impairs blood-brain barrier function: Cellular and molecular mechanisms

Sleep is a physiological process that preserves the integrity of the neuro-immune-endocrine network to maintain homeostasis. Sleep regulates the production and secretion of hormones, neurotransmitters, cytokines and other inflammatory mediators, both at the central nervous system (CNS) and at the periphery. Sleep promotes the removal of potentially toxic metabolites out of the brain through specialized systems such as the glymphatic system, as well as the expression of specific transporters in the blood-brain barrier. The blood-brain barrier maintains CNS homeostasis by selectively transporting metabolic substrates and nutrients into the brain, by regulating the efflux of metabolic waste products, and maintaining bidirectional communication between the periphery and the CNS. All those processes are disrupted during sleep loss. Brain endothelial cells express the blood-brain barrier phenotype, which arises after cell-to-cell interactions with mural cells, like pericytes, and after the release of soluble factors by astroglial endfeet. Astroglia, pericytes and brain endothelial cells respond differently to sleep loss; evidence has shown that sleep loss induces a chronic low-grade inflammatory state at the CNS, which is associated with blood-brain barrier dysfunction. In animal models, blood-brain barrier dysfunction is characterized by increased blood-brain barrier permeability, decreased tight junction protein expression and pericyte detachment from the capillary wall. Blood-brain barrier dysfunction may promote defects in brain clearance of potentially neurotoxic metabolites and byproducts of neural physiology, which may eventually contribute to neurodegenerative diseases. This chapter aims to describe the cellular and molecular mechanisms by which sleep loss modifies the function of the blood-brain barrier.

Transcranial Irradiation Mitigates Paradoxical Sleep Deprivation Effect in an Age-Dependent Manner: Role of BDNF and GLP-1

The growing prevalence of aged sleep-deprived nations is turning into a pandemic state. Acute sleep deprivation (SD) accompanies aging, changing the hippocampal cellular pattern, neurogenesis pathway expression, and aggravating cognitive deterioration. The present study investigated the ability of Near Infra Red (NIR) light laser to ameliorate cognitive impairment induced by SD in young and senile rats. Wistar rats ≤ 2 months (young) and ≥ 14 months (senile) were sleep-deprived for 72 h with or without transcranial administration of NIR laser of 830 nm. Our results showed that NIR photobiomodulation (PBM) attenuated cognitive deterioration made by SD in young, but not senile rats, while both sleep-deprived young and senile rats exhibited decreased anxiety (mania)-like behavior in response to PBM. NIR PBM had an inhibitory effect on AChE, enhanced the production of ACh, attenuated ROS, and regulated cell apoptosis factors such as Bax and Bcl-2. NIR increased mRNA expression of BDNF and GLP-1 in senile rats, thus facilitating neuronal survival and differentiation. The present findings also revealed that age exerts an additive factor to the cellular assaults produced by SD where hippocampal damages made in 2-month rats were less severe than those of the aged one. In conclusion, NIR PBM seems to promote cellular longevity of senile hippocampal cells by combating ROS, elevating neurotrophic factors, thus improving cognitive performance. The present findings provide NIR as a possible candidate for hippocampal neuronal insults accompanying aging and SD.

The impact of 5-hydroxytryptophan supplementation on sleep quality and gut microbiota composition in older adults: A randomized controlled trial

BACKGROUND & AIMS

Sleep quality is a pivotal part of health and there is growing evidence on the association between gut microbiota composition and sleep quality. 5-Hydroxytryptophan (5-HTP) is known as a precursor of the sleep regulating neurotransmitter and hormone. However, efficacy of 5-HTP supplementation for improving sleep quality in older adults is unclear. Hence, the aim of this study is to assess the impact of 5-HTP supplementation on sleep quality and gut microbiota composition in older adults.

METHODS

This is a single-blinded, 12-week parallel randomized controlled trial. Thirty older adults (66 ± 3 years) in Singapore were randomly assigned to either consume or not consume 100 mg 5-HTP daily. Every 4 weeks, sleep quality was assessed via both subjective (Pittsburg Sleep Quality Index) and objective (actigraphy watch) measures. A global sleep score (GSS) was obtained from the PSQI, where a GSS>5 defines as poor sleeper while a GSS≤5 defines as good sleeper. Blood serotonin level, urine melatonin concentration, gut microbiota composition and stool short chain fatty acids (SCFA) content were assessed at week 0 and 12. This study was registered in clinicaltrials.gov as NCT04078724 (https://clinicaltrials.gov/ct2/show/NCT04078724).

RESULTS

5-HTP supplementation showed an overall favorable effect on certain sleep quality components and an increase in serum serotonin concentration. In particular, at week 12, not good sleepers but poor sleepers with 5-HTP supplementation were able to significantly improve subjective GSS (ΔSL5-HTP: -2.80 ± 1.10 min, p-value = 0.005). In addition, they showed an increase in microbiota diversity (Simpson5-HTP vs. SimpsonControl: 0.037 ± 0.032 a.u. vs. -0.007 ± 0.022 a.u.; pinteraction: 0.013) and relative abundance of SCFA producing bacteria in the gut.

CONCLUSIONS

5-HTP supplementation can improve certain sleep quality components in older adults and this benefit was more prominently observed in poor sleepers. 5-HTP was also able to improve the gut microbiota composition in poor sleepers.

Patient Experiences and Challenges in the Management of Autoinflammatory Diseases-Data from the International FMF & AID Global Association Survey

BACKGROUND

Autoinflammatory diseases (AIDs) are rare, mostly genetic diseases that affect the innate immune system and are associated with inflammatory symptoms. Both paediatric and adult patients face daily challenges related to their disease, diagnosis and subsequent treatment. For this reason, a survey was developed in collaboration between the FMF & AID Global Association and the Erlangen Center for Periodic Systemic Autoinflammatory Diseases.

METHODS

The aim of the survey was to collect the personal assessment of affected patients with regard to their current status in terms of diagnostic timeframes, the interpretation of genetic tests, the number of misdiagnoses, and pain and fatigue despite treatment.

RESULTS

In total, data from 1043 AID patients (829 adults and 214 children/adolescents) from 52 countries were collected and analyzed. Familial Mediterranean fever (FMF) (521/50%) and Behçet's disease (311/30%) were the most frequently reported diseases. The average time to diagnosis was 3 years for children/adolescents and 14 years for adults. Prior to the diagnosis of autoinflammatory disease, patients received several misdiagnoses, including psychosomatic disorders. The vast majority of patients reported that genetic testing was available (92%), but only 69% were tested. A total of 217 patients reported that no increase in acute-phase reactants was detected during their disease episodes. The intensity of pain and fatigue was measured in AID patients and found to be high. A total of 88% of respondents received treatment again, while 8% reported no treatment.

CONCLUSIONS

AID patients, particularly adults, suffer from significant delays in diagnosis, misdiagnosis, and a variety of symptoms, including pain and fatigue. Based on the results presented, raising awareness of these diseases in the wider medical community is crucial to improving patient care and quality of life.

Dental sleep medicine education among undergraduate dental students in France

INTRODUCTION

Dental sleep medicine (DSM) is an emerging discipline that studies the oral and maxillofacial causes and consequences of sleep-related problems. DSM is of upmost importance given the major medical challenge it represents. Therefore, to verify whether the future generation of dentists would be ready to face this challenge, the main objective of this study was to assess the degree of involvement of the French dental schools in teaching DSM at the undergraduate level.

MATERIALS AND METHODS

All 16 dental schools in France were asked to participate in the study by answering to an online survey concerning the DSM curriculum during the 2018-2019 academic year. The survey was addressed to the head of the dental school and/or to relevant course coordinators and contained 10 questions related to the type, content and amount of DSM teaching to undergraduate dental students.

RESULTS

Nine of the 16 (56.2%) French dental schools responded to the questionnaire. All these nine reported the inclusion of DSM in their undergraduate curriculum. The total average hours dedicated to teaching DSM was 5.6 h (SD 4.2; range 1-15 h). Seven of the 9 dental schools spent most of their DSM curriculum teaching time in the fifth year. All of them reviewed obstructive sleep apnoea and sleep-related bruxism and covered some topics related to therapies for sleep-related breathing disorders, such as the use of oral appliance.

CONCLUSION

The results of this survey showed that, although the average hourly volume is relatively high, the DSM teaching in French dental schools appeared to be non-standardised, heterogeneous and often lacunar. It is therefore essential to develop a common curriculum and implement it in all dental schools to provide undergraduate students a comprehensive and updated teaching in DSM.

The Six Pillars of Lifestyle Medicine in Managing Noncommunicable Diseases - The Gaps in Current Guidelines

BACKGROUND

Noncommunicable diseases (NCDs), also known as chronic diseases that are long-lasting, are considered the major cause of death and disability worldwide, and the six pillars of lifestyle medicine (nutrition, exercise, toxic control, stress management, restorative sleep, and social connection) play an important role in a holistic management of their prevention and treatment. In addition, medical guidelines are the most accepted documents with recommendations to manage NCDs.

OBJECTIVE

The present study aims to analyze the lack of lifestyle pillars concerning the major Brazilian medical guidelines for NCDs and identify evidence in the literature that could justify their inclusion in the documents.

METHOD

Brazilian guidelines were selected according to the most relevant causes of death in Brazil, given by the Mortality Information System, published by the Brazilian Ministry of Health in 2019. Journals were screened in the PUBMED library according to the disease and non-mentioned pillars of lifestyle.

RESULTS

Relevant causes of deaths in Brazil are acute myocardial infarction (AMI), diabetes mellitus (DM), and chronic obstructive pulmonary diseases (COPD). Six guidelines related to these NCDs were identified, and all address aspects of lifestyle, but only one, regarding cardiovascular prevention, highlights all six pillars. Despite this, a literature search involving over 50 articles showed that there is evidence that all the pillars can help control each of these NCDs.

CONCLUSION

Rarely are the six pillars of lifestyle contemplated in Brazilian guidelines for AMI, DM, and COPD. The literature review identified evidence of all lifestyle pillars to offer a holistic approach for the management and prevention of NCDs.

Application of Braided Piezoelectric Poly-l-Lactic Acid Cord Sensor to Sleep Bruxism Detection System with Less Physical or Mental Stress

For many years, we have been developing flexible sensors made of braided piezoelectric poly-l-lactic acid (PLLA) fibers that can be tied and untied for practical applications in society. To ensure good quality of sleep, the occurrence of bruxism has been attracting attention in recent years. Currently, there is a need for a system that can easily and accurately measure the frequency of bruxism at home. Therefore, taking advantage of the braided piezoelectric PLLA cord sensor's unique characteristic of being sewable, we aimed to provide a system that can measure the frequency of bruxism using the braided piezoelectric PLLA cord sensor simply sewn onto a bed sheet on which the subject lies down. After many tests using trial and error, the sheet sensor was completed with zigzag stitching. Twenty subjects slept overnight in a hospital room on sheets integrated with a braided piezoelectric PLLA cord. Polysomnography (PSG) was simultaneously performed on these subjects. The results showed that their bruxism could be detected with an accuracy of more than 95% compared with PSG measurements, which can only be performed in a hospital by a physician and are more burdensome for the subjects, with the subjects simply lying on the bed sheet with a braided piezoelectric PLLA cord sensor sewn into it.

Neurofibromin 1 mediates sleep depth in Drosophila

Neural regulation of sleep and metabolic homeostasis are critical in many aspects of human health. Despite extensive epidemiological evidence linking sleep dysregulation with obesity, diabetes, and metabolic syndrome, little is known about the neural and molecular basis for the integration of sleep and metabolic function. The RAS GTPase-activating gene Neurofibromin (Nf1) has been implicated in the regulation of sleep and metabolic rate, raising the possibility that it serves to integrate these processes, but the effects on sleep consolidation and physiology remain poorly understood. A key hallmark of sleep depth in mammals and flies is a reduction in metabolic rate during sleep. Here, we examine multiple measures of sleep quality to determine the effects of Nf1 on sleep-dependent changes in arousal threshold and metabolic rate. Flies lacking Nf1 fail to suppress metabolic rate during sleep, raising the possibility that loss of Nf1 prevents flies from integrating sleep and metabolic state. Sleep of Nf1 mutant flies is fragmented with a reduced arousal threshold in Nf1 mutants, suggesting Nf1 flies fail to enter deep sleep. The effects of Nf1 on sleep can be localized to a subset of neurons expressing the GABAA receptor Rdl. Sleep loss has been associated with changes in gut homeostasis in flies and mammals. Selective knockdown of Nf1 in Rdl-expressing neurons within the nervous system increases gut permeability and reactive oxygen species (ROS) in the gut, raising the possibility that loss of sleep quality contributes to gut dysregulation. Together, these findings suggest Nf1 acts in GABA-sensitive neurons to modulate sleep depth in Drosophila.

Prevalence of sleep disturbances in patients with long COVID assessed by standardised questionnaires and diagnostic criteria: A systematic review and meta-analysis

OBJECTIVE

We aimed to study the prevalence of sleep disturbances in patients with long COVID-19.

METHODS

We conducted a systematic review and meta-analysis of the pooled prevalence of sleep disturbances in patients post COVID-19. We systematically searched relevant studies from three databases, including Medline, Embase and Scopus. Original articles were included based on specific criteria: peer-reviewed, observational studies involving adults (18 or older) with confirmed post COVID-19 status through PCR testing and focused on sleep in the context of post COVID-19. Exclusion criteria included non-English articles, studies with insufficient data, and narrative/systematic reviews. The search was performed from 31st July 2023 to 15th August 2023. We identified 35 eligible papers; however, we excluded 6 studies which did not describe the sleep assessment. We used a random-effects meta-analysis model to estimate the pooled prevalence of sleep disturbances.

RESULTS

29 studies involved 13,935 long COVID-19 patients; approximately 39% of participants were male aged 18 to 97 years. The overall pooled prevalence of sleep disturbance was 46% (95% CI: 38-54%). Subgroup analyses revealed that the pooled prevalence of poor sleep quality was 56% (95% CI: 47-65%). The pooled prevalence of insomnia was 38% (95% CI: 28-48%). Finally, the pooled prevalence of excessive daytime sleepiness was 14% (95% CI: 0-29%).

CONCLUSION

Sleep disturbances are common in long COVID-19 patients. The healthcare sector should recognise these sleep issues and provide an early, effective treatment to prevent long-term sequelae of sleep problems.

Neural Control of REM Sleep and Motor Atonia: Current Perspectives

PURPOSE OF REVIEW

Since the formal discovery of rapid eye movement (REM) sleep in 1953, we have gained a vast amount of knowledge regarding the specific populations of neurons, their connections, and synaptic mechanisms regulating this stage of sleep and its accompanying features. This article discusses REM sleep circuits and their dysfunction, specifically emphasizing recent studies using conditional genetic tools.

RECENT FINDINGS

Sublaterodorsal nucleus (SLD) in the dorsolateral pons, especially the glutamatergic subpopulation in this region (SLDGlut), are shown to be indispensable for REM sleep. These neurons appear to be single REM generators in the rodent brain and may initiate and orchestrate all REM sleep events, including cortical and hippocampal activation and muscle atonia through distinct pathways. However, several cell groups in the brainstem and hypothalamus may influence SLDGlut neuron activity, thereby modulating REM sleep timing, amounts, and architecture. Damage to SLDGlut neurons or their projections involved in muscle atonia leads to REM behavior disorder, whereas the abnormal activation of this pathway during wakefulness may underlie cataplexy in narcolepsy. Despite some opposing views, it has become evident that SLDGlut neurons are the sole generators of REM sleep and its associated characteristics. Further research should prioritize a deeper understanding of their cellular, synaptic, and molecular properties, as well as the mechanisms that trigger their activation during cataplexy and make them susceptible in RBD.

A conserved role for frizzled in sleep architecture

Previous studies of natural variants in Drosophila melanogaster implicated the Wnt signaling receptor frizzled in sleep. Given that the Wnt signaling pathway is highly conserved across species, we hypothesized that frizzled class receptor 1 (Fzd1), the murine homolog of frizzled, would also have a role in sleep. Using a CRISPR transgenic approach, we removed most of the Fzd1 coding region from C57BL/6N mice. We used a video assay to measure sleep characteristics in Fzd1-deficient mice. As Wnt signaling is known to affect visuospatial memory, we also examined the impact of the deletion on learning and memory using the novel object recognition (NOR) paradigm. Fzd1-deficient mice had altered sleep compared to littermate controls. The mice did not respond differently to the NOR paradigm compared to controls but did display anxiety-like behavior. Our strategy demonstrates that the study of natural variation in Drosophila sleep translates into candidate genes for sleep in vertebrate species such as the mouse.

Mechanisms of Activation of Brain's Drainage during Sleep: The Nightlife of Astrocytes

The study of functions, mechanisms of generation, and pathways of movement of cerebral fluids has a long history, but the last decade has been especially productive. The proposed glymphatic hypothesis, which suggests a mechanism of the brain waste removal system (BWRS), caused an active discussion on both the criticism of some of the perspectives and our intensive study of new experimental facts. It was especially found that the intensity of the metabolite clearance changes significantly during the transition between sleep and wakefulness. Interestingly, at the cellular level, a number of aspects of this problem have been focused on, such as astrocytes-glial cells, which, over the past two decades, have been recognized as equal partners of neurons and perform many important functions. In particular, an important role was assigned to astrocytes within the framework of the glymphatic hypothesis. In this review, we return to the "astrocytocentric" view of the BWRS function and the explanation of its activation during sleep from the viewpoint of new findings over the last decade. Our main conclusion is that the BWRS's action may be analyzed both at the systemic (whole-brain) and at the local (cellular) level. The local level means here that the neuro-glial-vascular unit can also be regarded as the smallest functional unit of sleep, and therefore, the smallest functional unit of the BWRS.

Rest-activity rhythms across the lifespan: cross-sectional findings from the US representative National Health and Nutrition Examination Survey

STUDY OBJECTIVES

Rest-activity rhythms (RAR) may mark development, aging, and physical and mental health. Understanding how they differ between people may inform intervention and health promotion efforts. However, RAR characteristics across the lifespan have not been well-studied. Therefore, we investigated the association between RAR measures with demographic and lifestyle factors in a US nationally representative study.

METHODS

RAR metrics of interdaily stability (IS), intradaily variability (IV), relative amplitude (RA), and mean amplitude and timing of high (M10) and low (L5) activity were derived from 2011 to 2012 and 2013 to 2014 National Health and Nutrition Examination Survey (NHANES) actigraphy data. Population-weighted linear and logistic regression models were fit to examine the associations of age, gender, smoking, alcohol, season, body mass index (BMI), income-to-poverty ratio, and race/ethnicity with RAR. Significance was based on a false-discovery rate-corrected P-value of <0.05.

RESULTS

Among n = 12 526 NHANES participants (3-≥80 years), IS (higher = greater day-to-day regularity) and RA (higher = greater rhythm strength) generally decreased with age and were lower among males, whereas IV (higher = greater rhythm fragmentation) increased with age (p < 0.05). Dynamic changes in RAR trajectories were observed during childhood and adolescence. Income, BMI, smoking, and alcohol use were associated with RAR metrics, as well as season among children and teenagers (p < 0.05). RAR also differed by race/ethnicity (p < 0.05), with trajectories initially diverging in childhood and continuing into adulthood.

CONCLUSIONS

RAR differed by demographic and health-related factors, representing possible windows for public health intervention and sleep health promotion. RAR differences by race/ethnicity begin in childhood, are evident in early adolescence, and persist throughout adulthood.

Long-term associations between objective sleep quality and quantity and verbal memory performance in normal cognition and mild cognitive impairment

Introduction

Although the link between sleep and memory function is well established, associations between sleep macrostructure and memory function in normal cognition and Mild Cognitive Impairment remain unclear. We aimed to investigate the longitudinal associations of baseline objectively assessed sleep quality and duration, as well as time in bed, with verbal memory capacity over a 7-9 year period. Participants are a well-characterized subsample of 148 persons (mean age at baseline: 72.8 ± 6.7 years) from the Cretan Aging Cohort. Based on comprehensive neuropsychiatric and neuropsychological evaluation at baseline, participants were diagnosed with Mild Cognitive Impairment (MCI; n = 79) or found to be cognitively unimpaired (CNI; n = 69). Sleep quality/quantity was estimated from a 3-day consecutive actigraphy recording, whereas verbal memory capacity was examined using the Rey Auditory Verbal Learning Test (RAVLT) and the Greek Passage Memory Test at baseline and follow-up. Panel models were applied to the data using AMOS including several sociodemographic and clinical covariates.

Results

Sleep efficiency at baseline directly predicted subsequent memory performance in the total group (immediate passage recall: β = 0.266, p = 0.001; immediate word list recall: β = 0.172, p = 0.01; delayed passage retrieval: β = 0.214, p = 0.002) with the effects in Passage Memory reaching significance in both clinical groups. Wake after sleep onset time directly predicted follow-up immediate passage recall in the total sample (β = -0.211, p = 0.001) and in the MCI group (β = -0.235, p = 0.02). In the total sample, longer 24-h sleep duration was associated with reduced memory performance indirectly through increased sleep duration at follow-up (immediate passage recall: β = -0.045, p = 0.01; passage retention index: β = -0.051, p = 0.01; RAVLT-delayed recall: β = -0.048, p = 0.009; RAVLT-retention index:β = -0.066, p = 0.004). Similar indirect effects were found for baseline 24-h time in bed. Indirect effects of sleep duration/time in bed were found predominantly in the MCI group.

Discussion

Findings corroborate and expand previous work suggesting that poor sleep quality and long sleep duration predict worse memory function in elderly. Timely interventions to improve sleep could help prevent or delay age-related memory decline among non-demented elderly.

Astrocytes: new evidence, new models, new roles

Astrocytes have been in the limelight of active research for about 3 decades now. Over this period, ideas about their function and role in the nervous system have evolved from simple assistance in energy supply and homeostasis maintenance to a complex informational and metabolic hub that integrates data on local neuronal activity, sensory and arousal context, and orchestrates many crucial processes in the brain. Rapid progress in experimental techniques and data analysis produces a growing body of data, which can be used as a foundation for formulation of new hypotheses, building new refined mathematical models, and ultimately should lead to a new level of understanding of the contribution of astrocytes to the cognitive tasks performed by the brain. Here, we highlight recent progress in astrocyte research, which we believe expands our understanding of how low-level signaling at a cellular level builds up to processes at the level of the whole brain and animal behavior. We start our review with revisiting data on the role of noradrenaline-mediated astrocytic signaling in locomotion, arousal, sensory integration, memory, and sleep. We then briefly review astrocyte contribution to the regulation of cerebral blood flow regulation, which is followed by a discussion of biophysical mechanisms underlying astrocyte effects on different brain processes. The experimental section is closed by an overview of recent experimental techniques available for modulation and visualization of astrocyte dynamics. We then evaluate how the new data can be potentially incorporated into the new mathematical models or where and how it already has been done. Finally, we discuss an interesting prospect that astrocytes may be key players in important processes such as the switching between sleep and wakefulness and the removal of toxic metabolites from the brain milieu.

The effect of 24-hour sleep deprivation on subjective time perception

In this study, we investigated the effect of 24-h total sleep deprivation on subjective time perception. Twenty-five participants aged 18-35 years (13 female and 12 male) were recruited. Time perception and cognitive assessments were performed twice: after a regular night's sleep and following a 24-h sleep deprivation. The retrospective and prospective tasks were used to measure time perception. In order to prevent order effect, the test orders were randomized. The Stroop test and the Wechsler Memory Scale-III were used to evaluate attention, processing speed, and memory. The repeated measures ANOVA was used to examine gender-by-sleep deprivation interactions on time perception. We found that retrospective time perception was significantly prolonged after sleep deprivation (p < 0.05). Women had a shorter prospective time estimation rate after adequate sleep than men, but this difference disappeared after sleep deprivation. The Stroop test showed improvement in cognitive flexibility after sleep deprivation (p < 0.05), and short-term or working memory appeared unaffected by one night of sleep deprivation. There was a negative correlation between sleepiness rate and working memory function in female subgroup. The results suggest that even short-term sleep deprivation can significantly affect time perception, which may have important implications in critical situations.

The relationship between sleep duration and thyroid function in the adult US population: NHANES 2007-2012

OBJECTIVE

Sleep disturbance is a common problem in the general population. Sleep deprivation or dysfunction can have profound health consequences. However, how sleep duration is associated with thyroid function remains unclear. This study was thus developed to examine the association between sleep duration and thyroid function in the US adult population.

METHODS

A total of 8102 participants from the NHANES 2007-2012 dataset were included in this study. Weighted data analyses were conducted, and the link between sleep duration and thyroid function was probed using linear regression models with smoothed curve fitting. Stratified analyses were also performed.

RESULTS

Weighted mean (standard deviation) values for study variables were as follows: sleep duration 6.85 (0.02) hours, thyroid-stimulating hormone (TSH) 1.86 (0.03) mIU/ml, serum free T3 3.20 (0. 01) pg/mL, serum free T4 0.80 (0.01) ng/dL, serum total T3 115.12 (0.64) ng/dL, serum total T4 7.81 (0.04) ug/dL, TPOAb 16.20 (1.53) IU/mL, TgAb 5.75 (0.73) IU/mL, and Tg 15.11 (0.46) ng/mL. In unadjusted analyses, increased sleep duration was associated with higher serum TSH levels and decreased FT3 levels. After adjustment for potential confounders, a significant negative relationship was detected between sleep duration and FT3 levels in participants with ≤7 hours of sleep. When sleep duration exceeded 7 hours, no significant changes in FT3 levels were observed after further increases in sleep duration.

CONCLUSION

Increased sleep duration was related to decreased FT3 levels, primarily at short sleep durations, and this correlation was no longer evident when participants reached the recommended healthy sleep duration.

A Systematic Review of Publications on the Associations Between Sleep Architecture and Arterial Hypertension

Sleep research has garnered substantial interest among scientists owing to its correlation with various diseases, particularly elevated blood pressure observed in patients with obstructive sleep apnea. This systematic review aims to identify and analyze publications exploring the associations between sleep architecture and arterial hypertension. A comprehensive search of PubMed (MEDLINE), Scopus, and Embase databases yielded 111 reports, of which 7 manuscripts were included in the review. Four of the studies reported a significant reduction in the duration of the N3 phase of sleep in hypertensive patients, while 2 studies found a statistically significant reduction in the duration of the N2 and rapid eye movement (REM) stages of sleep. Three studies indicated increased sleep fragmentation in hypertensive patients. They showed a longer duration of the N1 stage of sleep, shorter duration of overall sleep time, and an increased apnea-hypopnea index in hypertensive patients. These findings underscore the association between the duration of non-REM/REM sleep stages and elevated BP, providing substantial evidence. Moreover, a notable increase in sleep fragmentation was observed among patients with hypertension. However, further research is warranted to expand and deepen our understanding of this intricate relationship. This systematic review serves as a valuable resource, guiding future investigations and contributing to advancements in the field of sleep and arterial hypertension.

Influencing factors of sleep disorders and sleep quality in healthcare workers during the COVID-19 pandemic: A systematic review and meta-analysis

AIM

The aim of this study was to identify the influencing factors of sleep disorders and sleep quality in healthcare workers during the COVID-19 pandemic.

DESIGN

Systematic review and meta-analysis of observational research.

METHODS

The databases of the Cochrane Library, Web of Science, PubMed, Embase, SinoMed database, CNKI, Wanfang Data, and VIP were systematically searched. The quality of studies was assessed using the Agency for Healthcare Research and Quality evaluation criteria and the Newcastle-Ottawa scale.

RESULTS

A total of 29 studies were included, of which 20 were cross-sectional studies, eight were cohort studies, and 1 was a case-control study; 17 influencing factors were finally identified. Greater risk of sleep disturbance was associated with female gender, single relationship status, chronic disease, insomnia history, less exercise, lack of social support, frontline work, days served in frontline work, department of service, night shift, years of work experience, anxiety, depression, stress, received psychological assistance, worried about being infected, and degree of fear with COVID-19.

CONCLUSIONS

During the COVID-19 pandemic, healthcare workers did have worse sleep quality than the general population. The influencing factors of sleep disorders and sleep quality in healthcare workers are multifaceted. Identification and timely intervention of resolvable influencing factors are particularly important for preventing sleep disorders and improving sleep.

PATIENT OR PUBLIC CONTRIBUTION

This is a meta-analysis of previously published studies so there was no patient or public contribution.

Integrating sleep health into resilience research

Sleep is a biological necessity that is a critical determinant of mental and physical well-being. Sleep may promote resilience by enhancing an individual's biological preparedness to resist, adapt and recover from a challenge or stressor. This report analyzes currently active National Institutes of Health (NIH) grants focussed on sleep and resilience, specifically examining the design of studies that explore sleep as a factor that promotes health maintenance, survivorship, or protective/preventive pathways. A search of NIH R01 and R21 research project grants that received funding in Fiscal Years (FY) 2016-2021 and focussed on sleep and resilience was conducted. A total of 16 active grants from six NIH institutes met the inclusion criteria. Most grants were funded in FY 2021 (68.8%), used the R01 mechanism (81.3%), were observational studies (75.0%), and measured resilience in the context of resisting a stressor/challenge (56.3%). Early adulthood and midlife were most commonly studied and over half of the grants focussed on underserved/underrepresented populations. NIH-funded studies focussed on sleep and resilience, or the ways in which sleep can influence an individual's ability to resist, adapt, or recover from a challenging event. This analysis highlights an important gap and the need to expand research focussed on sleep as a promotor of molecular, physiological, and psychological resilience.

In or out of sync? Concordance between parent and adolescent sleep varies by family context

Evidence suggests significant interrelations among parent and adolescent sleep (i.e., concordance). However, less is known regarding how parent-adolescent sleep concordance varies as a function of the family context. This study examined daily and average concordance between parent and adolescent sleep and explored adverse parenting and family functioning (e.g., cohesion, flexibility) as potential moderators. One hundred and twenty-four adolescents (Mage  = 12.90) and their parents (93% mothers) wore actigraphy watches assessing sleep duration, efficiency, and midpoint across 1 week. Multilevel models indicated daily (within-family) concordance between parent and adolescent sleep duration and midpoint. Average (between-family) concordance was found for sleep midpoint only. Family flexibility was linked with greater daily concordance in sleep duration and midpoint, whereas adverse parenting predicted discordance in average sleep duration and efficiency.

Sleep problems in children and adolescents in an attention deficit hyperactivity disorder service

OBJECTIVES

Sleep problems are common amongst children and adolescents with attention deficit hyperactivity disorder (ADHD). The purpose of this study was to investigate sleep problems in children and adolescents attending a specialist ADHD service.

METHODS

This was a cross-sectional online survey combined with a retrospective chart review, conducted in the ADHD Assessment, Diagnosis, Management, initiation, Research and Education (ADMiRE) service, the first public specialist ADHD service for young people in Ireland. Participants were caregivers of children and adolescents with ADHD attending ADMiRE. Sleep was assessed using The Children's Sleep Habits Questionnaire (CSHQ) and ADHD symptoms were assessed using an abbreviated version of the Swanson, Nolan and Pelham Teacher and Parent Rating Scale (SNAP-IV). Details regarding patient demographics, co-morbidities and medication were collected from patient records.

RESULTS

Eighty-four percent of young people scored above the clinical cut-off for a sleep disorder. The most frequently reported sleep problems were related to sleep onset and sleep duration, and 64% of respondents met the criteria for two or more sleep problems. ADHD severity was associated with greater sleep problems. Co-morbid physical, neurodevelopmental, and mental health disorders as well as stimulant use were not associated with greater sleep problems.

CONCLUSION

Sleep problems are very common amongst children and adolescents with ADHD. This study has demonstrated an association between more sleep problems and ADHD severity. These findings highlight the need for both effective ADHD treatment to ensure optional sleep in young people as well as effective interventions for sleep problems to prevent worsening of ADHD symptoms.

Long-term use of benzodiazepines in chronic insomnia: a European perspective

Chronic insomnia occurs in ~10% of the general population and has numerous negative health effects. The recommended first line treatment of cognitive behavior therapy for insomnia is not widely available for patients in Europe, so pharmacotherapies such as benzodiazepine receptor agonist agents (benzodiazepines and Z-drugs) are commonly used. However, their use is only recommended for ≤4 weeks due to unproven long-term efficacy in treatment of chronic insomnia, and the risk of tolerance, and the potential for dependence and misuse. In Europe, recommendations limiting the use of benzodiazepines (lowest dose and shortest duration) in chronic insomnia are not always followed, likely due to the lack of approved effective alternative therapies. Here we present a recent pilot survey of the pharmacological treatment landscape in chronic insomnia in five European countries (France, Germany, Italy, Spain, and the United Kingdom) and physicians' attitude toward treatment. The results suggest that benzodiazepines and Z-drugs are the most widely used treatments in chronic insomnia and are being used for longer than their recommended duration. Country variations in prescription rates were observed. Due to the known association between long-term benzodiazepine use and potential for developing dependence, further analysis of the literature was performed on the use and misuse of benzodiazepines. The results show that long-term use of benzodiazepines is associated with multiple consequences of treatment, including dependence, but also that previous use of benzodiazepines may increase the risk of opioid use disorder.

Metabolic risk factors and psychosocial problems independently explain poor sleep quality and obstructive sleep apnea symptoms among adults in urban India

STUDY OBJECTIVES

To determine if metabolic risk factors are associated with poor sleep quality and obstructive sleep apnea-like symptoms (OSA symptoms) independent of psychosocial problems and demographic and lifestyle factors in older Indian adults.

METHODOLOGY

We analyzed baseline data from adults (≥ 50 years) from a population-based cohort, the LoCARPoN study, in India. Variables were grouped as (a) demographic and lifestyle factors such as smoking, alcohol use, and physical activity; (b) psychosocial problems including symptoms of depression, anxiety, and perceived stress; and (c) metabolic risk factors including glycated hemoglobin, high-density lipoprotein, low-density lipoprotein, total cholesterol, body mass index, and hypertension. Variables were examined as predictors of poor sleep quality and OSA symptoms. Groups of variables were added stepwise to a logistic regression. Variance explained by nested models was quantified using McFadden's pseudo R2, and change was formally tested with the log-likelihood ratio test.

RESULTS

Among 7505 adults, the prevalence of poor sleep quality was 16.9% (95% CI: 16.0, 17.7), and OSA symptoms were present in 7.0% (95% CI: 6.4, 7.6). Psychosocial problems had a strong independent association with both poor sleep quality (pseudo R2 increased from 0.10 to 0.15, p < 0.001) and more OSA symptoms (pseudo R2 increased from 0.08 to 0.10, p < 0.001). Metabolic risk factors had a modest independent association with sleep quality (pseudo R2 increased from 0.14 to 0.15, p < 0.01), but a strong association with OSA symptoms (pseudo R2 increased from 0.08 to 0.10, p < 0.001).

CONCLUSION

Psychosocial and metabolic risk factors were independently associated with sleep quality and OSA symptoms. This fact implied that OSA symptoms may affect both mental health and physical health. Our findings have public health implications because the number and proportion of the elderly in India is increasing, while the prevalence of metabolic risk factors and psychosocial problems is high already. These facts have the potential to exacerbate not only the burden of sleep disorders and OSA symptoms but also associated cardiovascular and neurologic sequelae, further stretching the Indian health-care system.

Is exposure to chemical pollutants associated with sleep outcomes? A systematic review

Environmental exposures may influence sleep; however, the contributions of environmental chemical pollutants to sleep health have not been systematically investigated. We conducted a systematic review to identify, evaluate, summarize, and synthesize the existing evidence between chemical pollutants (air pollution, exposures related to the Gulf War and other conflicts, endocrine disruptors, metals, pesticides, solvents) and dimensions of sleep health (architecture, duration, quality, timing) and disorders (sleeping pill use, insomnia, sleep-disordered breathing)). Of the 204 included studies, results were mixed; however, the synthesized evidence suggested associations between particulate matter, exposures related to the Gulf War, dioxin and dioxin-like compounds, and pesticide exposure with worse sleep quality; exposures related to the Gulf War, aluminum, and mercury with insomnia and impaired sleep maintenance; and associations between tobacco smoke exposure with insomnia and sleep-disordered breathing, particularly in pediatric populations. Possible mechanisms relate to cholinergic signaling, neurotransmission, and inflammation. Chemical pollutants are likely key determinants of sleep health and disorders. Future studies should aim to evaluate environmental exposures on sleep across the lifespan, with a particular focus on developmental windows and biological mechanisms, as well as in historically marginalized or excluded populations.

Combined effect of work from home and work during nonwork time on sleep disturbance

Background

Owing to the coronavirus disease 2019 pandemic, being exposed to work from home and work during nonwork time simultaneously can lead to sleep disturbance; however, their combined effect is unclear. We aimed to investigate the combined effect of work from home and work during nonwork time on sleep disturbance.

Methods

This study used data from the Sixth Korean Working Condition Survey and included 27,473 paid workers. Logistic regression analysis was conducted to investigate the relationship between work from home, work during nonwork time, and sleep disturbance according to sex. We re-classified participants into 4 groups based on their working from home (No/Yes) and working during nonwork time (No/Yes). The relative excess risk due to interaction was calculated to examine the effect of exposure to both telecommuting and non-regular work hours on sleep disturbance.

Results

Workers exposed to work from home and work during nonwork time had significantly higher risks of sleep disturbance for all, men, and women workers (OR [95% CI]: 1.71 [1.46-2.02], 1.79 [1.43-2.23], and 1.64 [1.29-2.08] for work from home and 3.04 [2.70-3.42], 3.61 [3.09-4.22], and 2.41 [2.01-2.90] for work during nonwork time, respectively). Compared to those who were not exposed to both factors, when workers had both job factors, the ORs (95% CI) of sleep disturbance for all, men, and women were 3.93 (2.80-5.53), 5.08 (3.21-8.03), and 2.91 (1.74-4.87), respectively. The relative excess risk due to interaction of work from home and work during nonwork time was not significant for sleep disturbance.

Conclusions

Work from home and work during nonwork time were each associated with sleep disturbance, but the interaction between the two factors on sleep disturbance was not observed in both men and women.