Search Results (378)

It is noteworthy that disturbances in circadian rhythms and irregular sleep patterns can exert influence over the onset of Type 2 Diabetes (T2DM). Similarly, they can impact the development of Type 1 Diabetes (T1DM). In recent decades, there has been a notable trend towards both reduced and extended sleep durations, with a concurrent rise in occurrences of compromised sleep quality attributable to sleep fragmentation. These sleep disturbances, along with clinically recognized sleep disorders such as sleep apnea and insomnia, have been increasingly associated with a range of detrimental health outcomes. Of particular concern is the growing evidence linking sleep dysregulation to an augmented risk of metabolic diseases, including diabetes. In addition to sleep duration and quality, emerging research suggests that an individual’s chronotype, reflecting their preferred time for going to sleep, may also exert an influence on disease development, particularly T2DM. The habit of going to bed late when compared to the tendency of going to bed early tends to cause significant disruptions to daily social engagements. Eventually, this misalignment may lead to discrepancies in sleep schedules between weekdays and weekends, commonly referred to as social jetlag. The current review aims to discuss the complex relationship between circadian rhythm misalignment, triggered by improper sleep habits such as short or long sleep duration, disrupted chronotype, social jetlag, and sleep disorders, on the subsequent impact on the development of diabetes. Overall, current evidence suggests that circadian rhythm disruption and sleep disorders contribute significantly to metabolic dysregulation and diabetes risk, highlighting the importance of sleep health in prevention and management of diabetes. Full article

Background/Objectives: Circadian rhythm disruption is linked to cognitive decline, yet it remains unclear how behavioral and physiological rhythm markers are differently associated with cognition in amnestic mild cognitive impairment (aMCI). The primary aim of this study was to compare sleep–wake timing, rest–activity rhythm (RAR), and dim light melatonin onset (DLMO) between patients with aMCI and cognitively normal controls. Exploratory analyses further examined their associations with domain-specific cognitive performance. Methods: Eighteen aMCI patients and 21 cognitively normal controls (NC) enrolled. Cognitive function was assessed using the Korean version of the Consortium to Establish a Registry for Alzheimer’s Disease Neuropsychological Battery (CERAD-K). Participants underwent 5-day actigraphy to assess sleep–wake timing and non-parametric RAR variables, including interdaily stability (IS), intradaily variability (IV), and relative amplitude (RA). DLMO was determined from hourly salivary melatonin samples collected over five hours before sleep onset under dim-light conditions. Group comparisons of circadian markers were conducted as the primary analyses, and generalized linear models were used for exploratory analyses of associations between circadian markers and cognitive outcomes. Results: Groups did not significantly differ in sleep–wake timing, RAR parameters and DLMO. Sleep–wake timing variables and DLMO were not significantly associated with cognitive performance. Higher IS was associated with better visuospatial memory and executive function, whereas higher RA was associated with poorer verbal memory among aMCI patients. Conclusions: Although sleep–wake timing and melatonin phase did not differ between groups nor predict cognitive performance, higher daily rhythm stability was linked to better non-verbal memory and executive functioning. In contrast, high RA may relate to poorer verbal memory in aMCI, suggesting that elevated RA may not reflect true circadian robustness required for optimal cognition. Full article

Light exposure is a primary zeitgeber for the human circadian system and plays a key role in shaping sleep–wake patterns during adolescence, a period marked by biological sensitivity and social constraints. How the temporal organization and spectral composition of daily light exposure differ between weekdays and weekends remains poorly understood. Eighteen adolescents (15–17 years) were monitored for seven days using wrist actigraphy with integrated light sensors. Sleep parameters, nonparametric circadian rhythm indices, and time-resolved profiles of ambient and spectral (blue, green, and red) light exposure were analyzed. Repeated-measures ANOVA tested the effects of time of day and day type. Total sleep time and time in bed were longer on weekdays than on weekends (p < 0.05), while sleep latency and WASO did not differ. Circadian indices indicated preserved rhythmic organization. Light exposure showed a robust diurnal profile, with higher spectral irradiance on weekends (p < 0.001), especially in the morning and early afternoon. Significant time × day-type interactions were observed across all spectral bands (p < 0.001), indicating systematic reshaping of daily light profiles. Adolescents exhibit weekday–weekend differences in the temporal and spectral organization of light exposure, affecting the amplitude and shape of overall daily profiles. Full article

Grazing is a widespread land use practice with significant implications for biodiversity and ecosystem functioning. Wild ungulates, as key components of terrestrial ecosystems, play a vital role in maintaining ecosystem health. Dietary overlap exposes wild ungulates to intense competition with livestock, yet the effects of grazing on them remain underexplored. Using camera-trapping data from Xinglong County in the mountains of Southeast China, we investigated the spatiotemporal responses of eight wild ungulates to livestock (cattle and horses). Our results showed the following: (1) The potential distribution of suitable habitats for ungulates was primarily shaped by elevation (ELE), distance to temple (DTT), precipitation of the coldest quarter (bio19), and distance to water (DTW). Among the species, blue sheep (Pseudois nayaur) showed the strongest response to livestock presence. (2) Spatially, most ungulates appeared to avoid livestock; forest musk deer (Moschus berezovskii) showed spatial avoidance of horses. (3) Temporally, the daily activity patterns of most ungulates generally showed low to moderate overlap with those of cattle. These findings suggest that livestock grazing may be associated with negative effects on wild ungulates in Xinlong County. Given the ecological importance of ungulates, the need to maintain wildlife community integrity, and the long history of grazing in the region, further research is warranted to understand the role of livestock in shaping wildlife communities. Full article

Circadian clocks generate daily rhythms of gene expression that influence physiology, disease, and responses to therapeutics, yet how circadian transcription differs between juvenile and adult organisms remains unresolved. Here, we used genome-wide eXcision Repair sequencing (XR-seq) to quantify transcription-coupled repair as an indirect, high-sensitivity measure of transcription. We profiled the brain, liver, kidney, and testis from juvenile and adult C57BL6/J mice across a 24 h cycle and show that XR-seq enables sensitive circadian transcription mapping. In all organs except the testis, rhythmic transcription phases clustered near dawn and dusk. While core clock gene rhythms are largely preserved between juveniles and adults, rhythms of many clock-controlled genes differ markedly by age. Rhythmic genes are strongly organ-specific yet their overlap between ages is limited, indicating substantial developmental changes in circadian control. Together, these data provide a multi-organ map of juvenile versus adult circadian transcription and indicate that adult therapeutic schedules may not translate to juveniles. Full article

Urban disaster management frequently relies on isolated single-hazard assessments and static census data. This conventional approach systematically obscures the highly dynamic, time-varying nature of population exposure to co-located environmental hazards. This study develops an observation-based, time-adaptive multi-hazard exposure prioritization framework to quantify these spatiotemporal variations. We integrate seismic amplification susceptibility, derived from shear-wave velocity estimates, and empirical pluvial flooding footprints with hourly dynamic living population data at a 250 m grid resolution in Seoul, South Korea. Results indicate that multi-hazard integration refines spatial prioritization, with 11% of high-priority areas diverging from single-hazard models, primarily driven by highly amplifiable alluvial deposits. Furthermore, dynamic living population data revealed clear diurnal exposure shifts. Business districts exhibited a daytime-to-nighttime exposure ratio of 3.35, whereas residential areas showed an inverse ratio of 0.69, demonstrating that identical physical conditions generate markedly different exposure patterns depending on the daily urban rhythm. Based on these temporal dynamics, we classified high-priority zones into Persistent (79.4%), Day-peak (10.3%), and Night-peak (10.3%) transition types. These findings suggest that urban exposure must be managed as a time-varying attribute rather than a static feature. The proposed classification supports targeted mitigation: structural improvements for Persistent areas, dynamic crowd management for Day-peak zones, and localized alerts for Night-peak zones. Driven by globally accessible mobile data, this framework provides a transferable foundation for exposure-informed urban resilience planning across diverse metropolitan environments. Full article

Circadian rhythms are predictable biological patterns that recur about every 24 h and, in mammals such as humans, are entrained to daylight by the hypothalamic suprachiasmatic nucleus (SCN). Although light is a potent zeitgeber for the SCN, cells outside of the SCN can synchronize to daily nutrient and metabolic cues. In these tissues, nutrient metabolic processes are regulated by the molecular clock in anticipation of food availability or scarcity. Furthermore, nutrients and metabolic processes themselves may act upon members of the molecular clock to regulate their expression and activity. These interactions maintain synchrony between the SCN and food-entrainable clocks when activity and nutrient intake align. However, the light-entrainable SCN and food-entrainable clocks can become desynchronized, particularly in modern society where humans are commonly exposed to shift work and jet lag. Therefore, the mechanisms for sensing nutrients at specific times of day are critical components of circadian timekeeping and organismal homeostasis. In the following narrative review, we aim to synthesize current evidence on time-of-day-dependent nutrient sensing in mammalian systems, examine how nutrient-derived signals and metabolic processes interact with molecular clock mechanisms across cellular and tissue levels, and evaluate the integration of central and peripheral clocks in regulating gene expression, energy utilization, and organismal homeostasis, including the impacts of feeding cycles and circadian disruption. While previous reviews have discussed circadian nutrient metabolism, this review provides conceptual support for the role of nutrients as time-of-day signaling mechanisms. Full article

Background: Atrial fibrillation (AF) is a common arrythmia in post-myocardial infarction (MI) cardiac rehabilitation (CR) cohorts, and beta-adrenergic signaling remodeling and rate-control pharmacotherapy may influence functional capacity. Methods: We retrospectively studied 117 consecutive male post-MI patients referred to outpatient CR. Functional capacity was assessed with a 6 min walk test (6MWT). AF was identified from clinical records, and beta-blocker exposure was unified as carvedilol-equivalent daily dose. Results: Beta-blockers were used in 94.1% of patients and AF was present in 10.3%. Patients with AF were older (72.7 ± 6.6 vs 58.1 ± 9.3 years) and walked shorter distances (430.0 [375.0–497.5] vs. 540.0 [480.0–570.0] m). In the prespecified interaction model, age remained independently associated with lower 6MWT (−4.29 m/year; p < 0.001), AF was associated with lower 6MWT (−137.21 m; p = 0.01), and the beta-blocker dose × AF interaction was positive (+6.78; p = 0.02; R² = 0.44). Importantly, the beta-blocker dose was not associated with 6MWT in patients without AF, whereas a positive association was observed in AF (B = 7.55, p = 0.04). Conclusions: In this exploratory analysis, AF identified a subgroup with markedly reduced functional capacity in early post-MI CR, supporting the potential of phenotype-informed assessment. Additionally, the association between beta-blocker dose and 6MWT distance differed by rhythm status. These preliminary findings require confirmation in larger prospective cohorts. Full article

Sleep abnormalities and circadian rhythm disruptions are frequently observed in psychiatric disorders such as depression and schizophrenia. However, most previous studies have examined circadian rhythms and sleep separately, limiting understanding of how these processes interact within individuals. This study examined circadian and sleep characteristics in depression and schizophrenia compared with healthy controls using multi-day wrist actigraphy. Circadian rhythms were assessed using parametric and non-parametric measures of rest–activity patterns, and sleep metrics were derived using a validated actigraphy-based algorithm. Distinct patterns were observed across diagnostic groups. Schizophrenia showed widespread disruption in daily activity patterns, with altered timing and reduced rhythm strength. Sleep was longer but highly fragmented, with frequent awakenings despite increased time in bed. In contrast, depression showed more limited changes, mainly in activity timing and overall activity levels, while sleep and daily patterns remained closer to controls. A key finding was the identification of distinct circadian–sleep profiles for each condition, with global disruption in schizophrenia and more selective alterations in depression. These findings show that combining circadian and sleep measures provides a clearer understanding of psychiatric disorders and may support monitoring and targeted interventions based on daily behavioral rhythms. Full article

Understanding how environmental factors such as shelter availability and hibernation influence amphibian behavior is critical for improving conservation and captive management. In this study, we examined the effects of shelter and hibernation on 24 h behavioral patterns of male Dybowski’s frogs (Rana dybowskii) across different age groups. Twenty adult and twenty juvenile frogs were observed during pre- and post-hibernation periods under controlled laboratory conditions using continuous video monitoring. Both adults and juveniles showed significantly increased resting behavior when provided with shelter, with adults resting more than 70% of the time and juveniles exceeding 80%. Hibernation induced clear changes in circadian rhythms, including shifts in peak activity times, and vocalizations increased post-hibernation in both age groups, reflecting physiological adjustments associated with reproductive activation. Juveniles displayed more pronounced activity rhythms and greater sensitivity to shelter availability, indicating age-specific differences in environmental adaptability. These findings demonstrate the importance of shelter in shaping behavioral patterns and highlight that hibernation leads to temporary but marked alterations in daily activity cycles. Full article

Heart failure is one of the most prevalent conditions worldwide, exerting a substantial impact on both prognosis and quality of life. It affects both psychological and physical domains, leading to multiple limitations in patients’ daily lives. Background/Objectives: The primary objective of this study was to identify clear factors related to disease severity, living conditions, and associated comorbidities that may negatively influence the quality of life of patients with heart failure. Methods: This study had a cross-sectional observational design and was conducted between 2024 and 2025 in the Department of Internal Medicine of the CF University Hospital in Cluj-Napoca, Romania. A total of 122 patients (mean age 67.9 ± 9.69 years, 62% women) diagnosed with heart failure, regardless of ejection fraction, and hospitalized in the Internal Medicine department during the study period were included. All participants self-administered the Minnesota Living with Heart Failure Questionnaire. Results: The analysis identified several factors associated with better quality of life, including female sex, atrial fibrillation with electrostimulated heart rhythm, type 2 diabetes mellitus, arterial hypertension, hepatitis, and chronic gastritis. Conversely, several factors were found to have a negative association with quality of life, such as advanced age, obesity, higher New York Heart Association (NYHA) functional class, reduced ejection fraction, valvular heart disease, obstructive sleep apnea syndrome, cervical–thoracic–lumbar polydiscopathy, hyperthyroidism, and hepatic steatosis. Conclusions: These results highlight the importance of key factors associated with quality of life in patients with heart failure. Full article

Background: Postoperative arrhythmias, especially atrial fibrillation (AF), are common complications of coronary artery bypass grafting (CABG) associated with prolonged hospitalization and adverse outcomes. This study aimed to assess the incidence of postoperative AF and identify demographic, clinical, and intraoperative predictors in CABG patients in Cyprus. Methods: This prospective, multicenter observational study was conducted in three cardiac surgery centers in Cyprus between September 2022 and April 2023. Adult elective CABG patients in preoperative sinus rhythm were included; emergency cases and those with prior arrhythmias or conduction disturbances were excluded. Data on demographic, clinical, intraoperative, and postoperative variables, including norepinephrine infusion duration, were collected daily. Postoperative arrhythmias were systematically recorded during hospitalization. Statistical analyses included descriptive statistics, bivariate tests, and multivariable logistic regression to identify independent predictors of postoperative atrial fibrillation. Results: Among 102 patients (mean age 66.8 years, 78.4% male), postoperative arrhythmias occurred in 26.5%. AF was most frequent (20.6%), followed by ventricular tachycardia (2.9%), atrial tachycardia (1.0%), atrioventricular block (1.0%), and one fatal asystole. Key independent predictors of AF were increasing age, atrial enlargement, severely reduced left ventricular ejection fraction (<30%), and prolonged norepinephrine infusion. Conclusions: Postoperative AF remains a prevalent and clinically significant complication after CABG. The association with norepinephrine duration underscores the importance of careful hemodynamic management. Further studies and AI-based prediction models may enhance individualized prevention strategies. Full article

Urban contemporary living has increasingly shifted emotional regulation inward, away from wider social networks and into tightly managed daily life. Within this landscape, dogs can become regulatory partners whose presence reshapes human rhythms, attention, and everyday sociability. This review examines how urban conditions—including risk-averse caregiving, dense living, and reduced opportunities for sustained social contact—reconfigure emotional co-regulation within human–dog relationships and, in turn, human emotional environments. Drawing on research from behavioural science, physiology, comparative ethology, psychology, and the social sciences (2010–2025), it treats attachment, synchrony, and social buffering as interconnected processes. Across disciplines, evidence suggests that dogs and humans often settle emotionally together, showing coupled dynamics in behaviour and physiology. Such coupling can support stress buffering and recovery, yet under chronic human stress or heightened control it may stabilise shared vigilance and dependence, concentrating regulatory work within the dyad. These effects are conditional: when dogs lack stable, reciprocal social buffering—especially with conspecifics—the dyad may be less able to support recovery, and synchrony may tilt toward vigilance rather than calm. Seen this way, human–dog bonds function as part of the emotional infrastructure of contemporary cities, shaping how calm, uncertainty, and social contact are organised. Full article

The circadian clock enables organisms to anticipate daily recurring events and synchronize their internal rhythms with environmental cues, such as light, aligning with the day/night cycle. Central to the molecular mechanisms of the circadian clock and light sensing are the Period (Per) 1 and 2 genes. While the roles of Per2 in astrocytes and neurons have been characterized, the specific contributions of Per1 remain less understood. Previous research has shown that Per2 in neurons, but not astrocytes, influences phase shifts, whereas the regulation of the circadian period involves Per2 in both cell types. In this study, we investigated the role of Per1 in neurons and astrocytes in modulating the circadian period and phase shifts. Using an Aschoff Type I protocol (constant darkness) combined with 15 min light pulses at circadian times (CT) 10, 14, and 22, we found that the absence of Per1 in neurons—but not in astrocytes—significantly affected both the circadian period and phase advance shifts in response to light at CT22. Full article

Background: This study investigated the diurnal variation in endurance performance and the corresponding ventilatory/metabolic responses during a maximal incremental cycling test. Methods: Thirty physically active young men (age = 23.5 ± 2.2 years; weekly exercise volume: ≥6 h·wk⁻¹) with regular daily routines were recruited for a randomized crossover study. Each participant completed two maximal incremental cycling tests to volitional exhaustion: one in the morning (07:00–09:00) and another in the evening (17:00–19:00). The two sessions were separated by a one-week washout period. Key ventilatory and metabolic variables, including maximal voluntary ventilation (MVV) and maximal oxygen uptake (VO_2max), were continuously measured, and time to exhaustion (TTE) was monitored. Paired-samples t-tests were used to compare morning versus evening outcomes. Results: Key performance and physiological variables, including MVV (p < 0.01), VO_2max (p < 0.01), and TTE (p < 0.01), were significantly improved in the evening as compared to the morning. Conclusions: Both ventilatory/metabolic function and endurance performance during a maximal incremental cycling test induce a pronounced diurnal rhythm in trained young men, with superior outcomes observed in the evening. Full article