The two-process model of sleep regulation: Beginnings and outlook

Sleep and male (In)Fertility: A comprehensive overview

Infertility affects millions of couples globally, with male factors contributing up to 50 % of cases. Despite the existing Assisted Reproduction Technologies (ART), decreased sperm quality and male infertility persist. Evidence suggests that sleep is crucial for normal reproductive function, and the noticeable increase in infertility rates aligns with the growing prevalence of sleep deprivation, suggesting a connection between both conditions. This literature review explores the possible links between sleep disturbances, with a special emphasis on insomnia, the most prevalent sleep disorder, and male reproductive health. It delves into the latest findings regarding factors such as sperm quality, hormone levels, and overall reproductive function from studies in mammals, both rodents and humans. Through a concise synthesis of these findings, we unveil potential mechanisms and provide crucial insights for clinicians and researchers in the field of reproductive health.

Snooze alarm use in a global population of smartphone users

Snooze alarm use is a common, but poorly understood human behavior. We explore the prevalence and characteristics of snooze alarm use in more than 3 million nights collected in a global sample of users of a sleep monitoring smartphone application. On the nights that participants logged a sleep session, more than half (55.6%) of the sessions ended with a snooze alarm. Of the sleep sessions ending with snooze alarm, snooze alarm was pressed on average 2.4 times (95% CI: 2.4-2.5) and the average duration of snooze alarm use was 10.8 minutes (95% CI: 10.7-10.9). We observed significantly more snooze alarm use in women as compared to men. Long sleep sessions (> 9 h) were more likely to end with snooze alarm use than recommended duration (7 to 9 h) or short (< 7 h) sleep sessions. Sleepers who went to bed earlier used snooze alarm less, while those who went to bed later than usual used the snooze alarm more. Future research is needed to understand the impact of snooze alarm use on daytime performance.

LPS-induced systemic inflammation disrupts brain activity in a region- and vigilance-state specific manner

Sepsis-associated encephalopathy (SAE) is a common complication of sepsis and the systemic inflammatory response syndrome that leads to lasting consequences in survivors. It manifests as early EEG changes that are region-, time- and state-specific, possibly reflecting distinct mechanisms of injury. Here, we investigated the effects of 5 mg/kg lipopolysaccharide (LPS) on hippocampal and cortical sleep-wake states, oscillatory and non-oscillatory neuronal activity, as well as on within- and between-state dynamics using state-space analysis. LPS induced rapid-onset severe temporal and spatial vigilance state fragmentation, which preceded all other spectral changes by ∼90 min. Thereafter, LPS led to specific destabilization and increased delta oscillatory activity in wakefulness, but not NREM sleep, although state transitions remained largely normal. Instead, reduced NREM delta power resulted from aperiodic spectrum changes. LPS specifically reduced higher frequency hippocampal gamma oscillations (60-80 Hz peak) in wakefulness, but not cortical high gamma or lower frequency gamma oscillations. These results suggest that disruption of sleep-wake patterns could serve as an early indicator of sepsis and associated encephalopathy, independent of spectral changes. Moreover, treatment aimed at stabilizing vigilance states in early stages of sepsis might prove to be a novel option preventing the development of further pathological neurophysiology, as well as limiting inflammation-related brain damage.

Disrupted Cortico-Striato-Thalamo-Cortical Circuitry and Sleep Disturbances in Obsessive-Compulsive Spectrum, Chronic Tic, and Attention-Deficit/Hyperactivity Disorders

ABSTRACT

The bidirectional relationship between sleep and obsessive-compulsive spectrum disorders (OCSDs), chronic tic disorders (CTDs), and attention-deficit/hyperactivity disorder (ADHD) is not well understood. To better treat individuals with these co-occurring sleep and developmental neuropsychiatric conditions, it is necessary to determine the common neural underpinnings to then target with treatment. Research has implicated dysregulated cortico-striatal-thalamo-cortical (CSTC) neurocircuitry in the development of CTDs, OCSDs, and ADHD. We review current literature to assess the state of knowledge about the neurocircuitry of OCSDs, CTDs, and ADHD, and their related sleep disturbances. Our review consistently implicates CSTC-pathway disruptions in OCSDs, CTDs, and ADHD, as well as dopamine and GABA dysregulation, primary neurotransmitters in CSTC circuitry, in sleep disorders. In addition, we highlight reports of subjective poor sleep and insomnia in adults with OCSDs, CTDs, and ADHD, and sleep movement disorders in adults with CTDs. The limited sleep research on youth with these conditions has demonstrated some similar findings. Unfortunately, much of the current research to date has not employed polysomnographic methods for objective sleep-related assessments. Future research should further clarify the neural association between these neuropsychiatric conditions and sleep disturbances to better guide potential therapeutic targets. Determining the most effective treatments for subjective sleep-related complaints in patients with these conditions will be crucial, particularly for determining treatment course-whether to prioritize treatment of the underlying condition, the specific sleep symptoms, or both simultaneously.

The impact of total sleep deprivation on attentional networks and its neural mechanisms: Based on the Attention Network Test

Sleep deprivation, both daily and occupational, has become a prevalent issue in modern society, significantly affecting individuals' attention functions. Traditionally, attention was viewed as a singular, unified system, but advances in neuroscience have revealed it as a network involving coordinated interactions across multiple brain regions. Posner and Petersen's Attention Network Theory delineates three distinct subcomponents - alerting, orienting, and executive control - based on anatomical localization and neurobiochemical mechanisms. However, most studies on sleep deprivation often overlook these subcomponents, treating attention as a generalized process. This paper aims to address this gap by investigating the effects of total sleep deprivation (TSD) on these attentional subcomponents and their potential neural mechanisms focusing on both the general healthy population and specific occupational groups. Using the Attention Network Test (ANT) paradigm and its variants, the findings reveal that TSD differentially affects the three subcomponents of attentional networks, with occupation-specific differences. Notably, the impact of TSD on executive control exhibits greater variability. The state instability hypothesis and local sleep theory are proposed to explain these neural mechanisms, suggesting that TSD disrupts attentional networks through an interplay of top-down state instability and bottom-up local sleep processes. Future research should refine experimental paradigms related to attentional networks, integrate cognitive neuroscience methodologies and computational modeling approaches, and expand investigations into sleep restriction. Such advancements will provide a more comprehensive understanding of how TSD affects attentional networks and further elucidate the interplay between the state instability hypothesis and local sleep theory.

Sleep as the Foundation of Brain Health

Sleep is a vital function, taking about one-third of a human lifetime, and is essential for achieving and maintaining brain health. From homeostatic neurophysiology to emotional and procedural memory processing to clearance of brain waste, sleep and circadian alignment remain paramount. Yet modern lifestyles and clinical practice often dismiss sleep, resulting in profound long-term repercussions. This chapter examines the roles of sleep and circadian rhythms in memory consolidation, synaptic plasticity, and clearance of metabolic waste, highlighting recent advances in neuroscience research. We explore how insufficient and disordered sleep-a public health concern-can impair cognition, escalate neurodegenerative risks, and compromise neurovascular integrity, thereby impacting brain health. These findings underscore the need for comprehensive screening for disturbed sleep and targeted interventions in clinical practice. Emerging interventions and AI-driven technologies may allow early detection and personalized and individualized treatments and improve outcomes. Overall, this chapter reaffirms that healthy sleep is indispensable at any level of neurological disease prevention-on par with the role of diet and exercise in cardiovascular health-and represents the foundation of brain health.

A novel method to separate circadian from non-circadian masking effects to enhance estimation of circadian timing and amplitude from core body temperature

STUDY OBJECTIVES

Circadian disruption contributes to adverse effects on sleep, performance, and health. One accepted method to track continuous daily changes in central circadian timing is to measure core body temperature (CBT), and establish daily, circadian-related CBT minimum time (Tmin). This method typically applies cosine-model fits to measured CBT data, which may not adequately account for substantial masking of circadian effects, and thus estimates of the circadian-related Tmin. This study introduced a novel physiology-grounded analytic approach to separate circadian from non-circadian effects on CBT, which we compared against traditional cosine-based methods.

METHODS

The dataset comprised 33 healthy participants (mean ± SD 32 ± 13 years) attending a 39-h in-laboratory study with an initial overnight sleep followed by an extended wake period. CBT data were collected at 30-s intervals via ingestible capsules. Our design captured CBT during both the baseline sleep period and during extended wake period (without sleep) and allowed us to model the influence of circadian and non-circadian effects of sleep, wake, and activity on CBT using physiology-guided generalized additive models.

RESULTS

Compared to the traditional cosine model, the new model exhibited superior fits to CBT (Pearson R 0.90 [95 %CI; [0.83-0.96] versus 0.81 [0.55-0.93]). The difference between estimated vs measured circadian Tmin, derived from the day without sleep, was better fit with our method (0.2 [-0.5,0.3] hours) versus previous methods (1.4 [1.1 to 1.7] hours).

CONCLUSIONS

This new method provides improved demasking of non-circadian influences compared to traditional cosine methods, including the removal of a sleep-related bias towards an earlier estimate of circadian Tmin.

Molecular basis identification and hypnotic drug interactions for cognitive impairment related to sleep deprivation

Chronic sleep deprivation can lead to cognitive impairment which makes it difficult to think, focus, and make comprehensive decisions. This in turn leads to the progression and increased risk of several diseases. This study aimed to explore potential drug targets and biomarkers underlying the increased disease risk due to sleep deprivation, including stress responses, immune dysfunction, and metabolic dysregulation. Four datasets namely GSE40562, GSE98566, GSE98582 for sleep deprivation, and GSE26576 normal brain cells were utilized to understand the molecular basis and potential drug targets associated with sleep deprivation. The GEO2R tool, Robust rank aggregations, and Venny were used to retrieve the common DEGs. Functional gene and pathway analyses were carried out via GO and the KEGG analyses. The STRING and CytoHuba plugins were utilized to identify the protein-protein interactions (PPIs) as well as the hub genes in the main PPI subnetworks following the drug interaction of the hub genes and GEPIA-based survival analysis of the DEGs. A total of 160 common DEGs were retrieved from all four datasets. Among them, 65 were down-regulated and 95 were up-regulated. TOP2A, AURKB, NEFL, CDC42, ASPM, GAP43, PVALB, NUF2, CALM1, TPR, KIF5B, KIF15, TROAP, NDC80, PBK, MKI67, SST, AHSP, ALAS2, and NEFH were retrieved as hub genes. While based on drug interaction, survival analysis and gene expression profile eight hub gene named TOP2A, AURKB, PVALB, CALM1, KIF5B, PBK, MKI67, and SST were found to be potential drug candidates and significantly correlated with infiltration levels of CD8 + T cells, B cells, macrophages, CD4 + T cells, neutrophils, and dendritic cells. These genes might play a role in sleep disorders via various pathways associated with neurodegeneration and diseases, potentially serving as biomarkers to support treatment and diagnosis.

Analysing the effect of social jetlag on burnout among shift nurse using a chained mediation model

The purpose of the present research is to explore the relationship between social jetlag and burnout among Chinese shift nurses. Furthermore, we seek to demonstrate how perceived stress and sleep quality play as chain mediators in this relationship. A cross-sectional study. There are 429 Chinese shift nurses data records included through one-on-one format using the subjects' sociodemographic information, the Munich Chronotype Questionnaire for shift workers (MCTQshift), the Chinese version of the 14-item Perceived Stress Scale (CPSS-14), the Pittsburgh Sleep Quality Index (PSQI), and the Chinese version of Maslach Burnout Inventory-General Survey. The positive correlations are found between social jetlag and burnout among Chinese shift nurses; perceived stress and sleep quality, respectively, play a partial mediating role in this relationship. Furthermore, perceived stress and sleep quality play a chain mediating role between social jetlag and burnout. These findings contribute to understanding the impact mechanism of social jetlag on shift nurses' burnout and provide a theoretical foundation for nurses managers to develop programs designed for reducing the burnout that affects shift nurses.

JACUZI-SD: An automated, high-throughput, minimally stressful approach to sleep depriving larval zebrafish

While sleep deprivation broadly disrupts health and well-being, the neural and molecular mechanisms that signal increased sleep pressure remain poorly understood. A key obstacle to progress is the fact that traditional methods for inducing sleep deprivation (SD) in animal models often introduce confounding stress or disrupt circadian rhythms. Here, we present JACUZI-SD (Jetting Automated Currents Under Zebrafish to Induce Sleep Deprivation), a fully automated, high-throughput system designed to induce sleep deprivation in larval zebrafish with minimal stress. By delivering randomized water pulses via a custom milli-fluidic device integrated with a 96-well plate and controlled by an Arduino, JACUZI-SD promotes wakefulness during the natural dark cycle without the stress associated with existing SD methods. Our results demonstrate that JACUZI-SD reduces total sleep time by 41-64% and elicits a robust rebound sleep characterized by increased sleep bout length following deprivation. Importantly, this method avoids activating the hypothalamic-pituitary-interrenal (HPI) stress axis, as shown by reduced stress marker expression compared to other sleep deprivation methods. Additionally, the system reliably activates known sleep pressure pathways, including upregulating galanin expression in the neurosecretory preoptic area, while also revealing biologically relevant inter-individual variability in homeostatic rebound responses. JACUZI-SD provides a powerful, minimally invasive platform for dissecting the neural and molecular underpinnings of sleep homeostasis in vertebrates.

Associations between real-life light exposure patterns and sleep behaviour in adolescents

One of the most striking changes in the regulation of sleep-wake behaviour during adolescence is circadian phase delay. Light exposure synchronises circadian rhythms, impacting sleep regulation, however, the influence of real-life light exposure on sleep variations remains less clear. We aimed to describe the sleep and light exposure patterns of high school students with comparable schedules and socio-economic backgrounds, and to evaluate whether there was any association between them, considering chronotype. We analysed five school days and two free days of actigraphy records, from 35 adolescents (24 female, mean age: 16.23 ± 0.60). The sample was described using the Sleep Regularity Index (SRI), chronotype (actigraphy MSFsc), and self-reported diurnal preference (Morning/Evening Scale). Regression models were constructed to assess the impact of light exposure (daytime and nighttime) on subsequent sleep episodes; and to confirm whether the associations could be an indirect consequence of chronotype. Despite following similar routines, the SRI varied considerably (48.25 to 88.28). There was compatibility between the actigraphy proxy for chronotype and the self-reported diurnal preference, extracted using the circadian rhythm scale for adolescents. Less light exposure during the day was associated with later sleep onset and shorter sleep duration. An increase of 100 lux in average daytime light exposure advance of 8.08 minutes in sleep onset and 7.16 min in sleep offset. When the regressions were controlled for chronotype, these associations persisted. These findings facilitate discussions regarding the behavioural aspect of the impact of real-life light exposure on sleep and its potential as a target for interventions aiming to enhance adolescents' sleep quality.

The relationship between shift work, sleep, and work hours on wellbeing

We investigated the role of sleep and work hours on wellbeing among day- and shift workers. We tested a mediation-moderation hypothesis proposing that; 1) sleep would mediate the association between the work schedule and the impact of sleep/sleepiness on wellbeing; 2) work hours would moderate the link between work schedule and sleep. We made random phone calls to 1,162 participants and identified 172-d and 130 shift workers that worked ≥35 h/week. The work schedule had a positive indirect effect on the impact of sleep/sleepiness via sleep duration (β=0.0511, SE=0.0309, [0.0008, 0.3219]. The relationship between shift work and sleep duration was negative (β=-0.35, SE=0.14, p<0.01), and sleep duration was negatively associated with a greater impact of sleep/sleepiness on wellbeing (β=-0.15, SE=0.06, p<0.02). The path between the work schedule and sleep duration was moderated by work hours; fewer work hours resulted in shift workers reporting a greater impact of sleep/sleepiness on wellbeing. The results support the mediation-moderation hypothesis. Work hours and sleep duration are key characteristics in work schedule design.

Unlocking Mysteries: Exploring the Dynamic Interplay among Sleep, the Immune System, and Curcumin in Contemporary Research

The scientific disciplines encompassing sleep, the immune system, and curcumin have garnered considerable interest due to their interconnectedness and potential implications for human health. Sleep is a crucial factor in maintaining optimal immune function, as it facilitates the release of cytokines, which are signaling molecules responsible for regulating immune responses. On the contrary, sleep deprivation has the potential of inhibiting immune function, thereby heightening the susceptibility to infection and disease. Curcumin, a naturally occurring polyphenol derived from the turmeric plant, has been observed to possess immunomodulatory characteristics through its ability to modulate the equilibrium between pro- and anti-inflammatory cytokines. It is worth noting that there is evidence suggesting that curcumin supplementation could enhance the quality of sleep. Scientific studies have indicated that curcumin supplementation has been associated with an increase in the duration of sleep and a decrease in wakefulness among individuals who are in good health. Additionally, curcumin supplementation has been found to enhance sleep quality and alleviate symptoms of depression in individuals diagnosed with major depressive disorder. The intricate interplay among sleep, the immune system, and curcumin is multifaceted, and scientific investigations indicate that curcumin may serve as a beneficial dietary adjunct to enhance immune function and optimize sleep quality. Nevertheless, additional investigation is required to fully comprehend the mechanisms through which curcumin alters the immune system and enhances sleep, as well as to ascertain the most effective dose and timing of curcumin supplementation.

Glia: the cellular glue that binds circadian rhythms and sleep

Glia are increasingly appreciated as serving an important function in the control of sleep and circadian rhythms. Glial cells in Drosophila and mammals regulate daily rhythms of locomotor activity and sleep as well as homeostatic rebound following sleep deprivation. In addition, they contribute to proposed functions of sleep, with different functions mapping to varied glial subtypes. Here, we discuss recent findings in Drosophila and rodent models establishing a role of glia in circadian or sleep regulation of synaptic plasticity, brain metabolism, removal of cellular debris, and immune challenges. These findings underscore the relevance of glia for benefits attributed to sleep and have implications for understanding the neurobiological mechanisms underlying sleep and associated disorders.

Sleep and Cancer

Background/Objectives: Sleep issues are common in the general population, and these problems occur even more frequently for people with cancer. Sleep problems may pre-exist a patient's cancer diagnosis, and there is a growing interest in understanding the impact of sleep on cancer development and progression. Sleep disorders may impact cancer through altered metabolism, impacts on immune response, and alterations in hormones and gene expression. Sleep disorders may also arise after, or be aggravated by, an individual's cancer and cancer treatment. Treating a person with cancer's sleep disorder may help improve their healing, mental health, cognition, and overall resilience. Methods: Studies examining a variety of aspects of the relationship between sleep and cancer were found by searching the National Library of Medicine and characterized by their specific information provided on the relationship between sleep and cancer. Results: This review article summarizes our current understanding of the complex inter-relationship between sleep and cancer, the underlying mechanisms that create these connections, and the methods and impact of treating sleep issues in cancer patients. The article also outlines an approach to sleep complaints for clinicians caring for patients with cancer. Conclusions: Significant research is still needed to understand the full relationship between sleep disorders and cancer. The impact of sleep issues on cancer and of cancer on sleep appears to be specific to the tissue and the molecular type of cancer. The treatment of sleep disorders is multimodal, and offers a promising avenue to improve the health and quality of life of cancer patients.

The Guardian of Dreams: The Neglected Relationship Between Sleep and Psychoanalysis

Knowledge about sleep was very limited at the time when Freud published his seminal work on the interpretation of dreams. He was also not interested in sleep, which was considered a problem of physiology; however, sleep appears to have a central role in his model, since dreaming is considered the guardian of sleep. The function of dreaming, according to Freud, is to protect sleep from disruption, with the dream working to avoid repressed stimuli interrupting the "biological" function of sleep. Before neurophysiological studies provided evidence that sleep is not a passive state, Freud also recognized sleep as an active process, as human beings voluntarily withdraw their attention from the external world to actively move to sleep. The discovery of REM sleep in the 1950s led psychoanalysts to see sleep as the necessary background to the occurrence of dreaming. Although Freud dismissed the clinical importance of sleep disturbances, viewing them as the somatic expression of an instinctual disturbance which would disappear during psychoanalytic treatment, successive authors highlighted the fact that sleep disturbances might have a more specific psychological significance. The similarities between the loss of self that occurs during sleep and the fragmentation of the identity experienced during schizophrenia represent an interesting and yet not fully explored area of research. Thanks to Freud's work, the desire to sleep assumes the important role of a psychological, active factor that contributes to the occurrence and function of sleep.

Chronotherapeutic considerations of benzodiazepine administration for agitation management in the emergency department

OBJECTIVE

Agitation in the emergency department (ED) affects up to 2.6% of encounters, posing significant risks to patients and caregivers. This review investigates the impact of circadian rhythms on benzodiazepine (BZD) pharmacokinetics and pharmacodynamics, focusing on how dosing time influences outcomes in managing acute agitation.

METHODS

A comprehensive literature search was performed using PubMed and Google Scholar (updated April 2024) to identify studies on BZD use in adult ED patients for acute agitation. Search terms included "antipsychotic agents," "lorazepam," "midazolam," "diazepam," and "emergency service." Studies focusing solely on substance intoxication were excluded. Priority was given to double-blind clinical trials, while open-label studies were included if no double-blind data were available. Referenced citations from identified publications were also reviewed.

RESULTS

Twenty-nine studies met the inclusion criteria: 16 randomised, double-blinded placebo-controlled trials, 5 prospective open-label studies and 8 retrospective reviews. Of these, 22 studies either did not report the time of day of patient recruitment or recruited patients over a year-long time frame. Four studies that specified the time of day of patient recruitment suggested a possible circadian variation in BZD sedation efficacy. Additionally, three studies that reported recruitment months revealed potential seasonal patterns in sedation requirements and efficacy.

CONCLUSIONS

Circadian rhythms appear to influence BZD metabolism and therapeutic effects, which could have implications for optimising treatment strategies. Aligning BZD dosing schemes with biological timing may enhance treatment outcomes and minimise adverse effects. Further research is needed to validate these findings and develop personalised chronopharmacotherapy strategies for acute agitation in the ED.

Phase angle between dim light melatonin onset and sleep timing during residential treatment prospectively predicts obsessive-compulsive symptoms

The relation between obsessive-compulsive disorder (OCD) and circadian rhythm disturbance has been increasingly acknowledged in recent years. While prior clinical studies have utilized patients' self-reported sleep behaviors, there is a need to also explore the measurable, biological aspects of circadian rhythms. The current study has two aims: first, to describe the biological circadian rhythms of individuals with OCD seeking intensive residential treatment, including their relationship with self-reported measures of sleep and OCD symptoms; and second, to examine longitudinal associations between biological circadian rhythms and OCD symptom severity during the course of residential treatment. Adults receiving residential treatment for OCD (n = 23) completed a procedure to measure their dim-light melatonin onset (DLMO) at admission, week two, week four, and discharge from treatment along with a battery of self-report assessments of OCD symptom severity and depression severity. Phase angle between DLMO and the midpoint of self-reported sleep was also calculated as a measure of the alignment between behavioral sleep-wake patterns and biological circadian rhythms at each time point. Cross-sectional correlations between these constructs were assessed and then cross-lagged panel models (CLPM) were fit to these data in order to examine the relation between 1) DLMO and OCD symptom severity across treatment and 2) phase angle of DLMO and midpoint of sleep and OCD symptom severity across treatment. Descriptive statistics indicate that sleep duration and timing were shifting closer toward general population averages across this period of treatment, perhaps due to newly supported bed and wake times in the treatment milieu. There were no significant cross-lagged paths between DLMO and OCD symptom severity during the first weeks of residential treatment. There was a significant cross-lagged path between DLMO phase angle from self-reported sleep midpoint and OCD symptom severity during the first weeks of residential treatment. Specifically, relatively shorter phase angle at admission was associated with less severe OCD symptoms at the second week of treatment; and relatively shorter phase angle at the second week of treatment was associated with more severe OCD symptoms at the fourth week of treatment. This study demonstrated the feasibility of measuring biological circadian rhythms in a residential treatment context and provided initial data demonstrating a longitudinal and dynamic relation between sleep, circadian rhythms, and OCD symptoms. Further study with larger samples is warranted. The non-linear pattern of relations across the course of this study also indicate that consideration of treatment processes and other factors not measured herein will strengthen future studies. Follow-up studies with residential treatment settings that continue salivary melatonin collection after treatment ends and patients return to their daily lives are also possible with this self-administered data collection procedure.

Circadian rhythm related genes signature in glioma for drug resistance prediction: a comprehensive analysis integrating transcriptomics and machine learning

BACKGROUND

Gliomas, 24% of all primary brain tumors, have diverse histology and poor survival rates, with about 70% recurring due to acquired or de novo resistance. Insomnia in patients is correlated strongly with circadian rhythm disruptions. The correlation between circadian rhythm disorders and drug resistance of some tumors has been proved. However, the precise mechanism underlying the relationship between glioma and circadian rhythm disorders has not been elucidated.

METHODS

Circadian rhythm-related genes (CRRGs) were identified using the least absolute shrinkage and selection operator (LASSO) regression, and stochastic gradient descent (SGD) was performed to form a circadian rhythm-related score (CRRS) model. The studies of immune cell infiltration, genetic variations, differential gene expression pattern, and single cell analysis were performed for exploring the mechanisms of chemotherapy resistance in glioma. The relationship between CRRGs and chemosensitivity was also confirmed by IC 50 (half maximal inhibitory concentration) analysis.

RESULT

Signatures of 16 CRRGs were screened out and identified. Based on the CRRS model, an optimal comprehensive nomogram was created, exhibiting a favorable potential for predicting drug resistance in samples. Immune infiltration, cell-cell communication, and single cell analysis all indicated that high CRRS group was closely related to innate immune cells. IC50 analysis showed that CRRG knockdown enhanced the chemosensitivity of glioma.

CONCLUSION

A significant correlation between CRRGs, drug resistance of glioma, and innate immune cells was found, which might hold a significant role in the drug resistance of glioma.

Circadian aspects in nonpharmacologic and pharmacologic treatment of insomnia

Insomnia disorder is a frequent sleep disorder leading to significant health and economic consequences. It has been proposed that individuals with insomnia may experience compromised deactivation systems of arousal, leading to a chronic state of hyperactivation of arousal known as hyperarousal, along with instability in the flip-flop system. Such disruptions may have a primarily impact on the sleep homeostatic drive process. Insomnia may indeed be associated with a disruption in the body's internal clock, known as chronodisruption. Despite the differentiation established in diagnostic nosology between insomnia disorder and circadian rhythm disorders, there is a significant body of evidence suggesting a complex interplay and frequent co-occurrence between these two conditions. In particular, circadian factors can predispose individuals to insomnia disorders, as well as precipitate and perpetuate their symptoms. Accordingly numerous pieces of evidence suggest that both pharmacologic and nonpharmacologic options for treating insomnia can have a resynchronization effect on circadian rhythms. The first-line treatment for chronic insomnia, according to current guidelines, is cognitive behavioral therapy for insomnia while pharmacologic interventions comprise of benzodiazepine receptor agonists also known as Z-drugs and short- to medium-acting benzodiazepines, melatonergic agonists such as ramelteon and melatonin 2mg prolonged release, and dual orexin receptor antagonists such as daridorexant, suvorexant, and lemborexant. At the same time, certain therapies recommended for circadian rhythm disorders can be utilized as adjunctive treatments for insomnia. Therefore, this chapter will discuss the circadian aspects of insomnia disorder and of its therapeutic approach. Furthermore, the effects of chronobiologic interventions, recommended for the treatment of circadian rhythm sleep-wake disorders, will be examined in individuals afflicted with chronic insomnia.

Effects of morning versus afternoon surgery on peri-operative disturbance of sleep-wake timing: An observational study

INTRODUCTION

The circadian timing system regulates diurnal sleep-wake rhythm. Previously, we showed that, in patients undergoing elective surgery, sleep-wake timing is altered and post-operative sleep quality is reduced. However, how the timing of the surgical procedure affects the disturbance and what other factors affect this disturbance remain unknown.

METHODS

Single-centre prospective observational study investigating the influence of surgery timing on post-operative sleep in adult patients (≥18 years) undergoing elective surgery. Sleep-wake timing was measured from three nights before until seven nights after surgery with a daily sleeping log. Primary outcome was post-operative midpoint of sleep shift between patients undergoing morning and afternoon surgeries. Secondary outcomes included factors affecting sleep timing disturbance and changes in subjective sleep quality.

RESULTS

We included 259 patients: 144 patients underwent morning procedures (08:00 h-12:00 h) and 115 underwent afternoon procedures (12:00 h-17:00 h). Both groups had significant phase advance of midpoint of sleep on the night after surgery when compared with three nights before surgery (mean - 00:41 h, 95% CI -00:27 h to -00:54 h, p < .001, for morning surgery and mean - 00:28 h, 95% CI -00:09 h to -00:46 h, p = .003, for afternoon surgery). However, there was no between-group difference (mean - 00:13 h, 95% CI -00:35 h-00:09 h, p = .25). Reduction of sleep quality was also similar. Phase advance was larger for patients with an evening chronotype or with lower pre-operative sleep quality. Decline of sleep quality after surgery was larger for patients with an evening chronotype, longer procedures or better pre-operative sleep quality.

CONCLUSION

Our results suggest that the timing of surgery between 08:00 h and 17:00 h does not modulate the effect of anaesthesia and surgery on phase of the sleep-wake rhythm in patients undergoing elective surgery with a low pre-operative risk of delirium.

EDITORIAL COMMENT

Timing of surgery may impact post-operative sleep. However, in this prospective cohort study of elective surgical patients, sleep-wake timing and post-operative sleep quality did not differ between those undergoing morning versus afternoon surgery.

A New Perspective in Epileptic Seizure Classification: Applying the Taxonomy of Seizure Dynamotypes to Noninvasive EEG and Examining Dynamical Changes across Sleep Stages

Epilepsy, a neurological disorder characterized by recurrent unprovoked seizures, significantly impacts patient quality of life. Current classification methods focus primarily on clinical observations and electroencephalography (EEG) analysis, often overlooking the underlying dynamics driving seizures. This study uses surface EEG data to identify seizure transitions using a dynamical systems-based framework-the taxonomy of seizure dynamotypes-previously examined only in invasive data. We applied principal component and independent component (IC) analysis to surface EEG recordings from 1,177 seizures in 158 patients with focal epilepsy, decomposing the signals into ICs. The ICs were visually labeled for clear seizure transitions and bifurcation morphologies (BifMs), which were then examined using Bayesian multilevel modeling in the context of clinical factors. Our analysis reveals that certain onset bifurcations (saddle node on invariant circle and supercritical Hopf) are more prevalent during wakefulness compared with their reduced rate during nonrapid eye movement (NREM) sleep, particularly NREM3. We discuss the possible implications of our results in the context of modeling approaches and suggest additional avenues to continue this exploration. Furthermore, we demonstrate the feasibility of automating this classification process using machine learning, achieving high performance in identifying seizure-related ICs and classifying interspike interval changes. Our findings suggest that the noise in surface EEG may obscure certain BifMs, and we suggest technical improvements that could enhance detection accuracy. Expanding the dataset and incorporating long-term biological rhythms, such as circadian and multiday cycles, may provide a more comprehensive understanding of seizure dynamics and improve clinical decision-making.

The intertwined relationship between circadian dysfunction and Parkinson's disease

Neurodegenerative disorders represent a leading cause of disability among the elderly population, and Parkinson's disease (PD) is the second most prevalent. Emerging evidence suggests a frequent co-occurrence of circadian disruption and PD. However, the nature of this relationship remains unclear: is circadian disruption a cause, consequence, or a parallel feature of the disease that shares the same root cause? This review seeks to address this question by highlighting and discussing clinical evidence and findings from experiments using vertebrate and invertebrate animal models. While research on causality is still in its early stages, the available data suggest reciprocal interactions between PD progression and circadian disruption.

Role of sleep and neurochemical biomarkers in synaptic plasticity related to neurological and psychiatric disorders: A scoping review

Sleep is vital for maintaining physical and mental well-being, impacting cognitive functions like memory and learning through neuroplasticity. Sleep disturbances prevalent in neurological and psychiatric disorders exacerbate cognitive decline, imposing societal burdens. Exploring the relationship between sleep and neuroplasticity elucidates the mechanisms influencing cognition, particularly amidst the prevalent sleep disturbances in these clinical populations. While existing reviews provide valuable insights, gaps remain in understanding the neurophysiological mechanisms underlying sleep and cognitive function. This scoping review aims to investigate the characteristic patterns of sleep parameters and neurochemical biomarkers in reflecting neuroplasticity changes related to neurological and psychiatric disorders and to explore how these markers interact and influence cognition at the molecular level. Studies involving adults and older adults were included, excluding animal models and the paediatric population. Selected studies explored the relationship between sleep parameter or neurochemical biomarker changes and cognitive impairment, reflecting underlying neuroplasticity changes. Peer-reviewed articles, clinical trials, theses, and dissertations in English were included while excluding secondary research and non-peer-reviewed sources. A three-step search strategy was executed following the updated Joanna Briggs Institute methodology for scoping reviews. Published studies were retrieved from nine databases, grey literature, expert recommendations, and hand-searching of the included studies' bibliography. A basic qualitative content synthesis of 34 studies was conducted per JBI's scoping review guidance. Slow-wave and Rapid-Eye Movement sleep, sleep spindles, sleep cycle disruption, K-Complex(KC) density, Hippocampal sEEG, BDNF, IL-6, iNOS mRNA expression, plasma serotonin, CSF Aβ-42, t-tau and p-tau proteins, and serum cortisol revealed associations with cognitive dysfunction. Examining the relationship between sleep parameters, neurochemical biomarkers, and cognitive function reveals neuronal mechanisms that guide potential therapeutic interventions and enhance quality patient care.

Elevated Bile Acids Induce Circadian Rhythm Sleep Disorders in Chronic Liver Diseases

BACKGROUND & AIMS

Sleep disorders (SDs) are common in chronic liver diseases (CLDs). Some SDs arise from impaired internal clock and are, hence, circadian rhythm SDs (CRSDs). Bile acids (BAs), whose levels are increased in many CLDs, reciprocally interact with circadian rhythm. This study explores the mechanisms underlying CRSDs in CLDs and novel therapies.

METHODS

We monitored the sleep of patients with CLD using actigraphic watch and established male mouse cholemia models by feeding with BA or bile duct ligation. Sleep-wake cycle and circadian rhythm were analyzed by electroencephalogram-electromyography and locomotor wheel-running experiments.

RESULTS

Patients with CLD showed CRSD-like phenotypes including increased night activity and early awakening, which were strongly correlated with increased BA levels (ie, cholemia). CRSDs, including shortened circadian period, were recapitulated in 2 cholemic mouse models. Mechanistically, elevated BAs in the suprachiasmatic nucleus (SCN) activated BA receptor Takeda G protein-coupled receptor 5 (Tgr5), which, in turn, increased the level and phosphorylation of Period2 (Per2), a master rhythm regulator, through extracellular signal-regulated kinase (Erk) and casein kinase 1ε (CK1ε). Per2 phosphorylation inhibited its nuclear import, which would release its transcriptional inhibition and expedite the circadian cycle. Cholemia also blunted the light entrainment response and light-induced phase change of SCN mediated by the neurons expressing gastrin releasing peptide through Tgr5-Per2 axis. BA sequestrant or CK1 inhibitor reversed the CRSDs in cholemic mice by restoring Per2 distribution.

CONCLUSIONS

Cholemia is a major risk factor for CRSDs in CLDs and, hence, a promising target in future clinical study.

Regular sleep habits in toddlers are associated with social development and brain coherence

OBJECTIVE

Although sleep habits are associated with the development of toddlers, factors affecting social development and brain function remain unclear. We aimed to elucidate the relationship between sleep habits and social development as well as brain coherence in toddlers.

METHODS

We used the data set at 1.5-2 years old, in the longitudinal study until 6 years old. We evaluated sleep parameters, such as average wake-up time, bedtime, nighttime sleep duration, total sleep duration, and the standard deviation (SD) of sleep habits. We also examined the development, including the social stimuli fixation percentage using Gazefinder® and electroencephalography (EEG) coherence between brain regions.

RESULTS

Seventy-two children (37 boys and 35 girls) were included. The fixation percentage for the human face was negatively correlated with the SD of the total sleep duration, nighttime sleep duration, nap duration, and bedtime (r = -0.516, p = 0.000; r = -0.331, p = 0.005; r = -0.330, p = 0.005; and r = -0.324, p = 0.005, respectively). The EEG analysis indicated that α-band coherence in the right centro-parietal area was negatively correlated with the total sleep duration (r = -0.283, p = 0.016). The path diagram demonstrated a direct significant effect of sleep duration irregularity on development including social communication and fixation percentage for human faces. Additionally, total sleep duration exhibited a direct effect on α cortical coherence in the right centro-parietal area.

CONCLUSIONS

In this study, we found an association between sleep irregularity and the development of social communication, preference for humans, and brain coherence in toddlers. We suggest that regular sleep plays an important role in promoting the development of social communication.

The association between vigour and flexibility with injury and alertness during shift work

Models of shift work and health suggest that individual differences in circadian rhythm characteristics may moderate the relationship between night shift work and injury, but this argument has not been directly tested. In this study, we tested the efficacy of two circadian rhythm characteristics-vigour and flexibility-as moderators of the path between shift work and injury. In addition, we aimed to replicate the association between vigour, flexibility, and alertness by time of day, and the measurement properties of the Circadian Type Inventory. We recruited 401 healthcare workers from Australia and Great Britain. After controlling for confounding variables, the results showed that vigour moderated the association between shift work and injury. Participants with values of vigour at the mean (β = 0.5120, p < 0.0013, 95% CI = [0.2018, 0.8223) and one standard deviation below the mean (β = 0.9048, p < 0.0001, 95% CI = [0.4648, 1.3447] reported significantly more injuries. No moderation was found for flexibility. Significant differences in alertness by time of day were observed in participants with higher levels of vigour compared to lower levels of vigour. No differences in alertness were observed for the flexibility scale. These results indicate that vigour may be a robust indicator of shift work tolerance. We replicated the posited two-factor structure of the Circadian Type Inventory, found the scales to have good reliability, and established for the first time, criterion-related validity for the vigour scale.

Morningness-Eveningness Preference and Motor Wake-Sleep Inertia in Adolescents

The aim of the present work was to analyze possible differences in the wake-sleep and sleep-wake transition in relation to adolescents' circadian preference using actigraphy. Overall, 729 participants were enrolled in the research and 443 of them wore actigraphs on the non-dominant wrist for at least three nights. According to the reduced Morningness-Eveningness Questionnaire for Children and Adolescents cut-off scores, 61 participants belonged to the evening-type category, while 38 participants belonged to the morning-type. We extracted the motor activity counts, minute-by-minute, during the wake-sleep and sleep-wake transitions, to depict the motor wake inertia and motor sleep inertia, respectively. We adopted the functional linear modeling statistical framework to examine the changes in both transitions according to chronotype. Overall, the results show a significantly higher motor wake inertia and lower motor sleep inertia in morning compared to evening types.

Harnessing Simple Animal Models to Decode Sleep Mysteries

Whether it involves human subjects or non-human animals, basic, translational, or clinical sleep research poses significant ethical challenges for researchers and ethical committees alike. Sleep research greatly benefits from using diverse animal models, each offering unique insights into sleep control mechanisms. The fruit fly (Drosophila melanogaster) is a superior genetic model due to its quick generation period, large progenies, and rich genetic tools. Its well-characterized genome and ability to respond to hypnotics and stimulants make it an effective tool for studying sleep genetics and physiological foundations. The nematode (Caenorhabditis elegans) has a simpler neural organization and transparent body, allowing researchers to explore molecular underpinnings of sleep control. Vertebrate models, like zebrafish (Danio rerio), provide insights into circadian rhythm regulation, memory consolidation, and drug effects on sleep. Invertebrate models, like California sea hare (Aplysia californica) and Upside-down jellyfish (Cassiopea xamachana), have simpler nervous systems and behave similarly to humans, allowing for the examination of sleep principles without logistical and ethical challenges. Combining vertebrate and invertebrate animal models offers a comprehensive approach to studying sleep, improving our understanding of sleep regulation and potentially leading to new drug discovery processes for sleep disorders and related illnesses.

Sleep Characteristics Among Children with a Parental History of Alcohol Use Disorder

Purpose of Review

The purpose of the review was to examine findings on sleep characteristics among children with a parental history of alcohol use disorder (CPHAUDs) in different age groups. We identified unanswered questions and discussed directions for future research. We also discussed the implications of these current findings on alcohol prevention and intervention programs.

Recent Findings

Parental ratings and youth report of sleep difficulties have been longitudinally associated with the emergence of alcohol use and alcohol-related problems among both CPHAUDsand non-CPHAUDs. There were inconsistent findings comparing sleep characteristics in these two groups. Studies that used self-report and parental ratings reported no or minimal differences while studies that used actigraphy and polysomnography found significant, albeit moderate but meaningful differences.

Summary

Current research shows that CPHAUDs and non-CPHAUDs are similar on most objective and subjective sleep measures. There are a few significant differences between the two groups that may have implications for the development of behavioral problems, substance use and other risk behaviors.

Alzheimer's disease and sleep disorders: A bidirectional relationship

Alzheimer's disease (AD) is the most prevalent dementia, pathologically featuring abnormal accumulation of amyloid-β (Aβ) and hyperphosphorylated tau, while sleep, divided into rapid eye movement sleep (REM) and nonrapid eye movement sleep (NREM), plays a key role in consolidating social and spatial memory. Emerging evidence has revealed that sleep disorders such as circadian disturbances and disruption of neuronal rhythm activity are considered as both candidate risks and consequence of AD, suggesting a bidirectional relationship between sleep and AD. This review will firstly grasp basic knowledge of AD pathogenesis, then highlight macrostructural and microstructural alteration of sleep along with AD progression, explain the interaction between accumulation of Aβ and hyperphosphorylated tau, which are two critical neuropathological processes of AD, as well as neuroinflammation and sleep, and finally introduce several methods of sleep enhancement as strategies to reduce AD-associated neuropathology. Although theories about the bidirectional relationship and relevant therapeutic methods in mice have been well developed in recent years, the knowledge in human is still limited. More studies on how to effectively ameliorate AD pathology in patients by sleep enhancement and what specific roles of sleep play in AD are needed.

Circadian Rhythm Disruption in Cancer Survivors: From Oncogenesis to Quality of Life

BACKGROUND

Circadian rhythms are approximately 24-hour cycles in physiological and behavioral processes. They are entrained to the external solar day via blue wavelength light. Disruptions in these intrinsic rhythms can lead to circadian dysfunction, which has several negative implications on human health, including cancer development and progression.

AIMS

Here we review the molecular mechanisms of circadian disruption and their impact on tumor development and progression, discuss the interplay between circadian dysfunction and cancer in basic scientific studies and clinical data, and propose the potential clinical implications of these data that may be used to improve patient outcomes and reduce cost of treatment.

MATERIALS & METHODS

Using scientific literature databases, relevant studies were analyzed to draw overarching conclusions of the relationship between circadian rhythm dysruption and cancer.

CONCLUSIONS

Circadian disruption can be mediated by a number of environmental factors such as exposure to light at night, shift work, jetlag, and social jetlag which drive oncogenesis. Tumor growth and progression, as well as treatment, can lead to long-term alterations in circadian rhythms that negatively affect quality of life in cancer survivors.

Morning resting hypothalamus-dorsal striatum connectivity predicts individual differences in diurnal sleepiness accumulation

While the significance of obtaining restful sleep at night and maintaining daytime alertness is well recognized for human performance and overall well-being, substantial variations exist in the development of sleepiness during diurnal waking periods. Despite the established roles of the hypothalamus and striatum in sleep-wake regulation, the specific contributions of this neural circuit in regulating individual sleep homeostasis remain elusive. This study utilized resting-state functional magnetic resonance imaging (fMRI) and mathematical modeling to investigate the role of hypothalamus-striatum connectivity in subjective sleepiness variation in a cohort of 71 healthy adults under strictly controlled in-laboratory conditions. Mathematical modeling results revealed remarkable individual differences in subjective sleepiness accumulation patterns measured by the Karolinska Sleepiness Scale (KSS). Brain imaging data demonstrated that morning hypothalamic connectivity to the dorsal striatum significantly predicts the individual accumulation of subjective sleepiness from morning to evening, while no such correlation was observed for the hypothalamus-ventral striatum connectivity. These findings underscore the distinct roles of hypothalamic connectivity to the dorsal and ventral striatum in individual sleep homeostasis, suggesting that hypothalamus-dorsal striatum circuit may be a promising target for interventions mitigating excessive sleepiness and promoting alertness.

Transcriptional dynamics of sleep deprivation and subsequent recovery sleep in the male mouse cortex

Sleep is an essential, tightly regulated biological function. Sleep is also a homeostatic process, with the need to sleep increasing as a function of being awake. Acute sleep deprivation (SD) increases sleep need, and subsequent recovery sleep (RS) discharges it. SD is known to alter brain gene expression in rodents, but it remains unclear which changes are linked to sleep homeostasis, SD-related impairments, or non-sleep-specific effects. To investigate this question, we analyzed RNA-seq data from adult wild-type male mice subjected to 3 and 5-6 hours of SD and 2 and 6 hours of RS after SD. We hypothesized molecular changes associated with sleep homeostasis mirror sleep pressure dynamics as defined by brain electrical activity, peaking at 5-6 hours of SD, and are no longer differentially expressed after 2 hours of RS. We report 5-6 hours of SD produces the largest effect on gene expression, affecting approximately half of the cortical transcriptome, with most differentially expressed genes (DEGs) downregulated. The majority of DEGs normalize after 2 hours of RS and are involved in redox metabolism, chromatin regulation, and DNA damage/repair. Additionally, RS affects gene expression related to mitochondrial metabolism and Wnt-signaling, potentially contributing to its restorative effects. DEGs associated with cholesterol metabolism and stress response do not normalize within 6 hours and may be non-sleep-specific. Finally, DEGs involved in insulin signaling, MAPK signaling, and RNA-binding may mediate the impairing effects of SD. Overall, our results offer insight into the molecular mechanisms underlying sleep homeostasis and the broader effects of SD.

Fly into tranquility: GABA's role in Drosophila sleep

Sleep is conserved across the animal kingdom, and Drosophila melanogaster is a prime model to understand its intricate circadian and homeostatic control. GABA (gamma-aminobutyric acid), the brain's main inhibitory neurotransmitter, plays a central role in sleep. This review delves into GABA's complex mechanisms of actions within Drosophila's sleep-regulating neural networks. We discuss how GABA promotes sleep, both by inhibiting circadian arousal neurons and by being a key neurotransmitter in sleep homeostatic circuits. GABA's impact on sleep is modulated by glia through astrocytic GABA recapture and metabolism. Interestingly, GABA can be coexpressed with other neurotransmitters in sleep-regulating neurons, which likely contributes to context-based sleep plasticity.

Sleep Health

AbstractSleep is what we spend (or should spend) one third of our lives doing. Unfortunately, many individuals fall short of their biological need for sleep many nights of the week. The reasons for this are varied and include professional or personal obligations and social determinants, including loud noises or safety concerns in one's neighborhood. This article reviews the architecture of sleep; evidence for sleep health, including impacts of sleep health on mental and emotional health as well as cognitive function and performance; and strategies for improving sleep health.

Alpha Synuclein Toxicity and Non-Motor Parkinson's

Parkinson's disease (PD) is a common multisystem neurodegenerative disorder affecting 1% of the population over the age of 60 years. The main neuropathological features of PD are the loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc) and the presence of alpha synuclein (αSyn)-rich Lewy bodies both manifesting with classical motor signs. αSyn has emerged as a key protein in PD pathology as it can spread through synaptic networks to reach several anatomical regions of the body contributing to the appearance of non-motor symptoms (NMS) considered prevalent among individuals prior to PD diagnosis and persisting throughout the patient's life. NMS mainly includes loss of taste and smell, constipation, psychiatric disorders, dementia, impaired rapid eye movement (REM) sleep, urogenital dysfunction, and cardiovascular impairment. This review summarizes the more recent findings on the impact of αSyn deposits on several prodromal NMS and emphasizes the importance of early detection of αSyn toxic species in biofluids and peripheral biopsies as prospective biomarkers in PD.

Restoration of locus coeruleus noradrenergic transmission during sleep

Sleep is indispensable for health and wellbeing, but its basic function remains elusive. The locus coeruleus (LC) powerfully promotes arousal by releasing noradrenaline. We found that noradrenaline transmission is reduced by prolonged wakefulness and restored during sleep. Fiber-photometry imaging of noradrenaline using its biosensor showed that its release evoked by optogenetic LC neuron activation was strongly attenuated by three hours of sleep deprivation and restored during subsequent sleep. This is accompanied by the reduction and recovery of the wake-promoting effect of the LC neurons. The reduction of both LC evoked noradrenaline release and wake-inducing potency is activity dependent, and the rate of noradrenaline transmission recovery depends on mammalian target of rapamycin (mTOR) signaling. The decline and recovery of noradrenaline transmission also occur in spontaneous sleep-wake cycles on a timescale of minutes. Together, these results reveal an essential role of sleep in restoring transmission of a key arousal-promoting neuromodulator.

Daytime sleepiness in insomnia: Are we focusing on what truly matters?

Insomnia, the most prevalent sleep disorder, is commonly associated with other mental and somatic disorders, making it a significant health concern. It is characterized by nighttime symptoms and daytime dysfunction, with sleepiness being a potential criterion for the latter. Sleepiness is a normal physiological state that is typically experienced near usual bedtime, in normal circumstances. In insomnia, it seems somewhat logical the idea that there is significant daytime sleepiness. However, the topic has been the subject of various discussions in sleep medicine, with studies yielding contradictory and inconsistent results. In this article, we aim to critically examine daytime sleepiness in individuals with insomnia disorder and propose an alternative approach to addressing it, both in clinical practice and research settings. It is crucial to further investigate the role of daytime sleepiness in insomnia, particularly by focusing on sleepiness perception as a more relevant dimension to explore in majority of patients. It is plausible that certain insomnia phenotypes are objectively sleepy during the day, but more studies are necessary, particularly with well-defined clinical samples. The implications of assessing sleepiness perception in insomnia for clinical practice are discussed, and new avenues for research are suggested.

Revolutionizing Sleep Health: The Emergence and Impact of Personalized Sleep Medicine

Personalized sleep medicine represents a transformative shift in healthcare, emphasizing individualized approaches to optimizing sleep health, considering the bidirectional relationship between sleep and health. This field moves beyond conventional methods, tailoring care to the unique physiological and psychological needs of individuals to improve sleep quality and manage disorders. Key to this approach is the consideration of diverse factors like genetic predispositions, lifestyle habits, environmental factors, and underlying health conditions. This enables more accurate diagnoses, targeted treatments, and proactive management. Technological advancements play a pivotal role in this field: wearable devices, mobile health applications, and advanced diagnostic tools collect detailed sleep data for continuous monitoring and analysis. The integration of machine learning and artificial intelligence enhances data interpretation, offering personalized treatment plans based on individual sleep profiles. Moreover, research on circadian rhythms and sleep physiology is advancing our understanding of sleep's impact on overall health. The next generation of wearable technology will integrate more seamlessly with IoT and smart home systems, facilitating holistic sleep environment management. Telemedicine and virtual healthcare platforms will increase accessibility to specialized care, especially in remote areas. Advancements will also focus on integrating various data sources for comprehensive assessments and treatments. Genomic and molecular research could lead to breakthroughs in understanding individual sleep disorders, informing highly personalized treatment plans. Sophisticated methods for sleep stage estimation, including machine learning techniques, are improving diagnostic precision. Computational models, particularly for conditions like obstructive sleep apnea, are enabling patient-specific treatment strategies. The future of personalized sleep medicine will likely involve cross-disciplinary collaborations, integrating cognitive behavioral therapy and mental health interventions. Public awareness and education about personalized sleep approaches, alongside updated regulatory frameworks for data security and privacy, are essential. Longitudinal studies will provide insights into evolving sleep patterns, further refining treatment approaches. In conclusion, personalized sleep medicine is revolutionizing sleep disorder treatment, leveraging individual characteristics and advanced technologies for improved diagnosis, treatment, and management. This shift towards individualized care marks a significant advancement in healthcare, enhancing life quality for those with sleep disorders.

Purkinje cell dysfunction causes disrupted sleep in ataxic mice

Purkinje cell dysfunction disrupts movement and causes disorders such as ataxia. Recent evidence suggests that Purkinje cell dysfunction may also alter sleep regulation. Here, we used an ataxic mouse model generated by silencing Purkinje cell neurotransmission (L7Cre;Vgatfx/fx) to better understand how cerebellar dysfunction impacts sleep physiology. We focused our analysis on sleep architecture and electrocorticography (ECoG) patterns based on their relevance to extracting physiological measurements during sleep. We found that circadian activity was unaltered in the mutant mice, although their sleep parameters and ECoG patterns were modified. The L7Cre;Vgatfx/fx mutant mice had decreased wakefulness and rapid eye movement (REM) sleep, whereas non-REM sleep was increased. The mutants had an extended latency to REM sleep, which is also observed in human patients with ataxia. Spectral analysis of ECoG signals revealed alterations in the power distribution across different frequency bands defining sleep. Therefore, Purkinje cell dysfunction may influence wakefulness and equilibrium of distinct sleep stages in ataxia. Our findings posit a connection between cerebellar dysfunction and disrupted sleep and underscore the importance of examining cerebellar circuit function in sleep disorders.

Near-Infrared-II Imaging Revealed Hypothermia Regulates Neuroinflammation Following Brain Injury by Increasing the Glymphatic Influx

Advanced in vivo imaging techniques have facilitated the comprehensive visual exploration of animal biological processes, leading to groundbreaking discoveries such as the glymphatic system. However, current limitations of macroscopic imaging techniques impede the precise investigation of physiological parameters regulating this specialized lymphatic transport system. While NIR-II fluorescence imaging has demonstrated advantages in peripheral lymphatic imaging, there are few reports regarding its utilization in the glymphatic system. To address this, a noninvasive transcranial macroscopic NIR-II fluorescence imaging model is developed using a cyanine dye-protein coupled nanoprobe. NIR-II imaging with high temporal and spatial resolution reveals that hypothermia can increase the glymphatic influx by reducing the flow rate of cerebrospinal fluid. In addition, respiratory rate, respiratory amplitude, and heart rate all play a role in regulating the glymphatic influx. Thus, targeting the glymphatic influx may alter the trajectory of immune inflammation following brain injury, providing therapeutic prospects for treating brain injury with mild hypothermia.

Influence of physical exercise on negative emotions in college students: chain mediating role of sleep quality and self-rated health

Background

Negative emotions in college students are a significant factor affecting mental health, with suicide behaviors caused by negative emotions showing an annual increasing trend. Existing studies suggest that physical exercise is essential to alleviate negative feelings, yet the intrinsic mechanisms by which it affects negative emotions have not been fully revealed.

Objective

Negative emotions in college students represent a significant issue affecting mental health. This study investigates the relationship between physical exercise and negative emotions among college students, incorporating sleep quality and self-rated health (SRH) as mediators to analyze the pathway mechanism of how physical exercise affects students' negative emotions.

Methods

A cross-sectional study design was utilized, employing online questionnaires for investigation. The scales included the Physical Activity Rating Scale-3 (PARS-3), the Depression Anxiety Stress Scales-21 (DASS-21), the Pittsburgh Sleep Quality Index (PSQI), and the 12-Item Short Form Health Survey (SF-12), resulting in the collection of 30,475 valid questionnaires, with a validity rate of 91%. Chain mediation tests and Bootstrap methods were applied for effect analysis.

Results

The proportions of university students engaged in low, medium, and high levels of physical exercise were 77.6, 13.1, and 9.3%, respectively. The proportions of students experiencing "very severe" levels of stress, anxiety, and depression were 4.5, 10.9, and 3.6%, respectively. Physical exercise was significantly positively correlated with self-rated health (r = 0.194, p < 0.01), significantly negatively correlated with sleep quality (r = -0.035, p < 0.01), and significantly negatively correlated with stress, anxiety, and depression (r = -0.03, p < 0.01; r = -0.058, p < 0.01; r = -0.055, p < 0.01). Sleep quality was significantly negatively correlated with self-rated health (r = -0.242, p < 0.01). Mediation effect testing indicated that sleep quality and self-rated health partially mediated the relationship between physical exercise and negative emotions, with total effect, total direct effect, and total indirect effect values of -1.702, -0.426, and - 1.277, respectively.

Conclusion

College students primarily engage in low-intensity physical activity. Sleep quality and self-rated health mediate the impact of physical exercise on students' negative emotions. A certain level of physical activity can directly affect students' emotional states and indirectly influence their negative emotions via sleep and self-rated health. Regular engagement in physical activities primarily positively impacts emotional states by enhancing mood stability and overall emotional resilience.

Test-retest reliability and time-of-day variations of perfusion imaging at rest and during a vigilance task

Arterial spin-labeled perfusion and blood oxygenation level-dependent functional MRI are indispensable tools for noninvasive human brain imaging in clinical and cognitive neuroscience, yet concerns persist regarding the reliability and reproducibility of functional MRI findings. The circadian rhythm is known to play a significant role in physiological and psychological responses, leading to variability in brain function at different times of the day. Despite this, test-retest reliability of brain function across different times of the day remains poorly understood. This study examined the test-retest reliability of six repeated cerebral blood flow measurements using arterial spin-labeled perfusion imaging both at resting-state and during the psychomotor vigilance test, as well as task-induced cerebral blood flow changes in a cohort of 38 healthy participants over a full day. The results demonstrated excellent test-retest reliability for absolute cerebral blood flow measurements at rest and during the psychomotor vigilance test throughout the day. However, task-induced cerebral blood flow changes exhibited poor reliability across various brain regions and networks. Furthermore, reliability declined over longer time intervals within the day, particularly during nighttime scans compared to daytime scans. These findings highlight the superior reliability of absolute cerebral blood flow compared to task-induced cerebral blood flow changes and emphasize the importance of controlling time-of-day effects to enhance the reliability and reproducibility of future brain imaging studies.

Associations of sleep disorders with all-cause MCI/dementia and different types of dementia - clinical evidence, potential pathomechanisms and treatment options: A narrative review

Due to worldwide demographic change, the number of older persons in the population is increasing. Aging is accompanied by changes of sleep structure, deposition of beta-amyloid (Aß) and tau proteins and vascular changes and can turn into mild cognitive impairment (MCI) as well as dementia. Sleep disorders are discussed both as a risk factor for and as a consequence of MCI/dementia. Cross-sectional and longitudinal population-based as well as case-control studies revealed sleep disorders, especially sleep-disorderded breathing (SDB) and excessive or insufficient sleep durations, as risk factors for all-cause MCI/dementia. Regarding different dementia types, SDB was especially associated with vascular dementia while insomnia/insufficient sleep was related to an increased risk of Alzheimer's disease (AD). Scarce and still inconsistent evidence suggests that therapy of sleep disorders, especially continuous positive airway pressure (CPAP) in SDB, can improve cognition in patients with sleep disorders with and without comorbid dementia and delay onset of MCI/dementia in patients with sleep disorders without previous cognitive impairment. Regarding potential pathomechanisms via which sleep disorders lead to MCI/dementia, disturbed sleep, chronic sleep deficit and SDB can impair glymphatic clearance of beta-amyloid (Aß) and tau which lead to amyloid deposition and tau aggregation resulting in changes of brain structures responsible for cognition. Orexins are discussed to modulate sleep and Aß pathology. Their diurnal fluctuation is suppressed by sleep fragmentation and the expression suppressed at the point of hippocampal atrophy, contributing to the progression of dementia. Additionally, sleep disorders can lead to an increased vascular risk profile and vascular changes such as inflammation, endothelial dysfunction and atherosclerosis which can foster neurodegenerative pathology. There is ample evidence indicating that changes of sleep structure in aging persons can lead to dementia and also evidence that therapy of sleep disorder can improve cognition. Therefore, sleep disorders should be identified and treated early.

Polysomnographic features associated with clonazepam and melatonin treatment in isolated REM sleep behavior disorder: Time for new therapeutic approaches?

AIMS

Although clonazepam (CLO) and melatonin (MLT) are the most frequently used treatments for REM sleep behavior disorder, the polysomnographic features associated with their use are little known. The aim of this study was to evaluate polysomnographic and clinical parameters of patients with idiopathic/isolated REM sleep behavior disorder (iRBD) treated chronically with CLO, sustained-release MLT, alone or in combination, and in a group of drug-free iRBD patients.

METHODS

A total of 96 patients were enrolled: 43 drug-free, 21 with CLO (0.5-2 mg), 20 with sustained-release MLT (1-4 mg), and 12 taking a combination of them (same doses). Clinical variables and polysomnography were collected.

RESULTS

Although clinical improvement was reported in all groups, MLT impacted sleep architecture more than the other treatments, with significant and large increase in N3 stage, moderate reduction in N2 and REM sleep, and moderate increase in REM latency. CLO moderately increased the percentage of both REM sleep and especially N2, while reducing N1 and wakefulness. Patients treated with both CLO and MLT did not show major changes in sleep architecture.

CONCLUSION

These results suggest that the administration of MLT or CLO impacts (positively) on sleep parameters of iRBD patients. However, there is a need to better stratify patients, in order to treat them in a targeted manner, depending on the patient's individual sleep architecture and expected differential effects of these agents.

Sleep deprivation reduced LPS-induced IgG2b production by up-regulating BMAL1 and CLOCK expression

Sleep deprivation (SD) weakens the immune system and leads to increased susceptibility to infectious or inflammatory diseases. However, it is still unclear how SD affects humoral immunity. In the present study, sleep disturbance was conducted using an sleep deprivation instrument, and the bacterial endotoxin lipopolysaccharide (LPS) was used to activate the immune response. It was found that SD-pretreatment reduced LPS-induced IgG2b+ B cells and IgG2b isotype antibody production in lymphocytes of spleen. And, SD-pretreatment decreased the proportion of CD4+T cells, production of CD4+T cells derived TGF-β1 and its contribution in helping IgG2b production. Additionally, BMAL1 and CLOCK were selectively up-regulated in lymphocytes after SD. Importantly, BMAL1 and CLOCK deficiency contributed to TGF-β1 expression and production of IgG2b+ B cells. Thus, our results provide a novel insight to explain the involvement of BMAL1 and CLOCK under SD stress condition, and their roles in inhibiting TGF-β1 expression and contributing to reduction of LPS induced IgG2b production.

Sleep and circadian rhythmicity as entangled processes serving homeostasis

Sleep is considered essential for the brain and body. A predominant concept is that sleep is regulated by circadian rhythmicity and sleep homeostasis, processes that were posited to be functionally and mechanistically separate. Here we review and re-evaluate this concept and its assumptions using findings from recent human and rodent studies. Alterations in genes that are central to circadian rhythmicity affect not only sleep timing but also putative markers of sleep homeostasis such as electroencephalogram slow-wave activity (SWA). Perturbations of sleep change the rhythmicity in the expression of core clock genes in tissues outside the central clock. The dynamics of recovery from sleep loss vary across sleep variables: SWA and immediate early genes show an early response, but the recovery of non-rapid eye movement and rapid eye movement sleep follows slower time courses. Changes in the expression of many genes in response to sleep perturbations outlast the effects on SWA and time spent asleep. These findings are difficult to reconcile with the notion that circadian- and sleep-wake-driven processes are mutually independent and that the dynamics of sleep homeostasis are reflected in a single variable. Further understanding of how both sleep and circadian rhythmicity contribute to the homeostasis of essential physiological variables may benefit from the assessment of multiple sleep and molecular variables over longer time scales.

The regulation of the pedunculopontine tegmental nucleus in sleep-wake states

The pedunculopontine tegmental nucleus (PPTg) plays a vital role in sleep/wake states. There are three main kinds of heterogeneous neurons involved: cholinergic, glutamatergic, and gamma-aminobutyric acidergic (GABAergic) neurons. However, the precise roles of cholinergic, glutamatergic and GABAergic PPTg cell groups in regulating sleep-wake are unknown. Recent work suggests that the cholinergic, glutamatergic, and GABAergic neurons of the PPTg may activate the main arousal-promoting nucleus, thus exerting their wakefulness effects. We review the related projection pathways and functions of various neurons of the PPTg, especially the mechanisms of the PPTg in sleep-wake, thus providing new perspectives for research of sleep-wake mechanisms.