Search Results (30)

High-altitude Andean climates present dual thermal pressure: daytime overheating risk coexists with nighttime heat loss within the same annual cycle. Aggregate energy indicators do not reveal the direction of thermal discomfort, limiting their utility for early-stage passive design. This study proposes a two-stage exploratory diagnostic framework for residential buildings in this context. Stage 1 uses window-to-wall ratio (WWR) and average opaque wall thermal transmittance (U-wall) to construct a preliminary thermal-risk alert matrix that is applicable at the schematic design phase. Stage 2 uses the post-simulation Discomfort Ratio (DR = Href/Hcal) to confirm the direction of thermal discomfort as overheating-dominant, heat-loss-dominant, or mixed. The framework was applied to 14 anonymized residential building energy simulation cases in Loja, Ecuador. Of 13 classifiable cases, DR assigned 5 to overheating-dominant, 5 to heat-loss-dominant, and 3 to mixed patterns; 6 cases with complete WWR and U-wall data populated the Stage 1 matrix. The surface-to-volume ratio and air changes per hour did not clearly discriminate across patterns. The framework is exploratory and corpus-specific; the alert matrix does not replace dynamic simulation and requires validation before normative or predictive application. Alongside DR, a bounded directional-intensity index (Normalized Discomfort Balance) and the total discomfort load are reported so that the direction and the magnitude of discomfort can be read jointly. Full article

Background/Objectives: Nocturnal glycemic variability in pediatric type 1 diabetes (T1D) disrupts caregiver sleep and quality of life; advanced hybrid closed-loop (AHCL) systems may be associated with reduced caregiver burden by providing more stable overnight glucose control. We aimed to evaluate changes in caregiver-reported sleep quality and continuous glucose monitoring (CGM) targets three months after transition to an AHCL system. Methods: We conducted a prospective single-center real-world study in a tertiary pediatric diabetes unit that included children aged 6–17 years with T1D who switched from continuous subcutaneous insulin infusion (MiniMed) and intermittently scanned CGM (FreeStyle Libre 2) to an AHCL system (MiniMed 780G) with Guardian 4 sensor. Caregivers completed the Pittsburgh Sleep Quality Index (PSQI) at baseline and after 3 months; CGM metrics (TIR 70–180 mg/dL, TAR1 180–250 mg/dL, TAR2 > 250 mg/dL, TBR1 54–70 mg/dL, TBR2 < 54 mg/dL) were extracted at the same time points. Analyses used Shapiro–Wilk, Wilcoxon signed-rank, Spearman correlations, and McNemar tests (α = 0.05). Results: Twenty-two caregivers completed baseline PSQI; 16 provided PSQI data at three months. The proportion with PSQI > 5 decreased from 56.3% to 18.8% (p = 0.034), and 81.3% showed lower global PSQI at 3 months (p = 0.018). The largest mean improvements were observed in daytime dysfunction (−0.94), subjective sleep quality (−0.81), and sleep duration (−0.63), with slight increases in sleep disturbance (+0.13) and sleep-medication use (+0.13). The proportion of participants meeting international CGM consensus targets improved: the percentage achieving TIR > 70% increased from 26.7% to 80.0% (p = 0.008); those meeting TAR > 180 mg/dL < 30% increased from 26.7% to 80.0% (p = 0.008); and those meeting TAR2 > 250 mg/dL < 5% increased from 20.0% to 53.3% (p = 0.008). Hypoglycemia-related targets showed no significant change, and no episodes of symptomatic or level 3 hypoglycemia were reported. Exploratory analyses suggested that poorer PSQI at 3 months was associated with greater Δ TBR1, and increases in TAR2 with higher sleep disturbance and sleep-medication use. Conclusions: Transition to an AHCL system was associated with improvements in caregiver-reported sleep and attainment of CGM consensus targets within three months. Residual nocturnal hyperglycemia was associated with features of ongoing sleep disturbance, highlighting the potential relevance of individualized alert settings, sleep-focused education, and inclusion of objective sleep measures in future studies. Full article

Despite the rapid expansion of photovoltaic (PV) installations over the past decade, challenges such as curtailments of renewable energy sources (RESs) and grid constraints continue to limit the capacity of Cyprus’ power system to accommodate higher solar penetration. In this context, grid reliability, defined as the ability to maintain stable operation by balancing supply and demand, minimizing curtailment, and reducing stress on the island network, has emerged as a critical concern. The deployment of PV-plus-storage systems offers a viable solution to enhance grid reliability while alleviating operational constraints. This paper presents a real-world case study of the first commercially deployed grid-connected PV-powered, battery-integrated electric vehicle (EV) charging station in Cyprus. Commissioned in May 2025, the system integrates a 60.32 kW_p rooftop PV array, a 100 kW/97 kWh battery energy storage system (BESS), and a 160 kW DC fast charger. A custom cloud-based energy management platform enables real-time monitoring, forecasting, and optimization under a zero-export scheme. High-resolution operational and weather data were collected between 15 May and 30 November 2025. Over this period, the integrated PV-battery system supplied 29% of the site’s total energy demand (self-sufficiency rate of 28.97%) and achieved a self-consumption rate of 98.69%. Such rates would not have been attainable with a pure PV system, given the depot’s evening-concentrated EV charging demand profile, which requires the BESS to time-shift daytime solar generation. The system reduced depot electricity costs by approximately 29%, generating €16,010 in savings and avoiding 26.47 tonnes of carbon dioxide (CO₂) emissions compared to a grid-only baseline. Beyond site-level performance, the system contributed to grid stress reduction by absorbing excess PV generation that would otherwise have been curtailed/wasted. Operational insights indicate minimal temperature-related issues, highlight the importance of automated fault detection and alerting to minimize downtime, and demonstrate how periodic operation strategies can optimize system performance and mitigate curtailment in Cyprus’s isolated grid. Full article

This paper examines the subjective annoyance associated with shared-bike electronic alert sounds (SBeASs), an emerging urban noise source. A study was conducted by employing extensive questionnaire surveys and psychoacoustic experiments. A preliminary survey (N = 1340) indicated that 90.6% of participants reported being impacted by SBeASs, with pronounced effects on nighttime rest and daytime work efficiency. In this study, SBeAS samples were taken from three prominent Chinese bike-sharing brands: Hello Bike, Meituan Bike, and DiDi Bike. Under laboratory conditions, subjective annoyance assessments (N = 28) for SBeASs were conducted at controlled sound pressure levels (SPLs) ranging from 45 to 65 dBA, with occurrence frequencies of 1, 3, and 5 s. Simultaneously, annoyance assessments were also conducted for two reference noise types: traffic noise and street noise. The results indicated a notable increase in annoyance levels related to SBeASs with rising SPL and increased occurrence frequency. Minor variations in annoyance were identified among different bike-sharing brands, which can be attributed to their distinct acoustic features. When the SPL was above 55 dBA, the DiDi Bike SBeASs produced considerably higher annoyance than those of other brands. This can be attributed to its elevated low-frequency energy, loudness, and roughness. Moreover, individuals exhibiting increased sensitivity to noise reported notably higher annoyance ratings on the SBeAS scale (p = 0.019). Under low-SPL conditions (45–55 dBA), the annoyance attributed to frequent SBeASs can exceed that caused by traffic noise and street noise at comparable SPLs, highlighting the distinct disruptive impact of abrupt sound sources. Full article

Introduction: Caffeine is the most widely consumed psychoactive stimulant worldwide and acts primarily through antagonism of adenosine A1 and A2A receptors, thereby reducing sleep pressure and promoting wakefulness. Although its alerting and performance-enhancing effects are well established, its influence on sleep-related electroencephalography (EEG) has been investigated across diverse paradigms with substantial methodological heterogeneity. This systematic and mechanistic review aimed to synthesize human evidence on how caffeine affects sleep architecture, quantitative sleep EEG, and neurophysiological markers of sleep homeostasis, and to interpret these findings within current models of adenosine-mediated sleep–wake regulation. Materials and Methods: A systematic search of PubMed/MEDLINE, Web of Science, Scopus, Embase, PsycINFO, ResearchGate, and Google Scholar was conducted for studies published between January 1980 and January 2026, with the final search performed on 10 January 2026. Eligible studies were original human investigations examining caffeine exposure or administration and reporting sleep-related EEG outcomes, including polysomnographic sleep staging, spectral EEG analyses, or other EEG-derived sleep metrics. Two reviewers independently screened records and assessed eligibility, with disagreements resolved by consensus. Data on study design, participant characteristics, caffeine interventions, EEG methodology, and outcomes were extracted using a predefined form. Risk of bias was evaluated using the RoB 2 and ROBINS-I tools. Owing to marked heterogeneity across studies, findings were synthesized narratively within a mechanistic interpretive framework. Results: Thirty-two studies were included. Across highly heterogeneous paradigms—including acute bedtime or evening dosing, daytime or repeated caffeine use before nocturnal sleep, administration during prolonged wakefulness followed by recovery sleep, withdrawal protocols, and ambulatory/home EEG monitoring—the most consistent finding was suppression of low-frequency NREM EEG activity, particularly slow-wave activity and the lowest delta frequencies. Caffeine frequently increased faster EEG activity, including sigma/spindle and beta ranges, producing a lighter, more aroused, and more wake-like sleep EEG profile. These effects were especially prominent during early-night NREM sleep and in recovery sleep after sleep deprivation, where caffeine attenuated the expected homeostatic rebound in low-frequency power. REM-related effects were less consistent, but some studies reported delayed REM timing and subtler alterations in REM EEG. Emerging evidence further suggests that caffeine increases EEG complexity and shifts sleep dynamics toward a more excitation-dominant state. Several studies indicated that quantitative EEG measures were more sensitive than conventional sleep-stage variables in detecting caffeine-related sleep disruption. Dose, timing, habitual caffeine use, withdrawal state, age, circadian context, and adenosinergic genetic variation, particularly involving ADORA2A, moderated the magnitude of effects. We also highlighted the connection between current results and sports and sports science. Conclusions: Caffeine reliably alters the neurophysiological architecture of human sleep in a direction consistent with reduced sleep depth and weakened homeostatic recovery. The overall evidence supports a mechanistic model centered on adenosine receptor antagonism, attenuation of sleep-pressure build-up and expression, and a shift toward greater cortical arousal during sleep. Sleep EEG appears to be a sensitive marker of these effects, often revealing physiological disruption even when conventional sleep architecture changes are modest. Future research should prioritize larger and more diverse samples, pharmacokinetic and pharmacogenetic characterization, and ecologically valid high-resolution sleep monitoring to clarify the real-world and functional consequences of caffeine-induced EEG changes. 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

This study examined the acute effects of electric lighting parameters (illuminance and correlated color temperature (CCT)) on vigilance and subjective alertness in older adults with mild cognitive impairment (MCI), with direct relevance to architectural lighting design in senior-care and rehabilitation settings. A within-subject experimental design was used with nine older adults diagnosed with MCI. Participants completed the NASA Psychomotor Vigilance Task (PVT) under four lighting conditions: 350 lux at 2700 K, 350 lux at 6500 K, 478 lux at 2700 K, and 478 lux at 6500 K. To account for repeated testing, practice-related changes across sessions were explicitly considered in the interpretation of outcomes. Subjective measures included the Karolinska Sleepiness Scale (KSS), the Groningen Sleep Quality Questionnaire, and two lighting evaluation surveys. Data analyses included paired-sample t-tests, effect sizes (Hedges’ g, η²), odds ratios, and confidence intervals. Across sessions, PVT performance improved overall, consistent with a practice effect. On Day 1 (350 lux), minimum reaction time did not differ between 2700 K and 6500 K; however, maximum reaction time was shorter under 6500 K, suggesting a selective reduction in extreme slow responses under cooler-spectrum light at baseline. On Day 2 (478 lux), minimum reaction time improved significantly under 6500 K, indicating faster responses under cooler-spectrum light when combined with higher illuminance and repeated exposure. False starts and lapses did not show consistent condition-dependent differences. Overall, cooler-spectrum light did not uniformly shift mean performance but instead appeared to stabilize performance by reducing extreme slow responses at baseline and enhancing rapid responses under higher illuminance with repeated exposure. These findings suggest that practice effects and spectral sensitivity jointly shape vigilance outcomes in older adults with MCI. From a building design perspective, the results support the potential value of tunable lighting (adjustable CCT and illuminance) as a non-pharmacological strategy to help sustain daytime alertness in senior-care and rehabilitation environments. Full article

Elevated indoor carbon dioxide (CO₂) concentrations are increasingly recognized as a critical determinant of occupant health and cognitive performance; however, the neurophysiological mechanisms linking CO₂ exposure to daytime sleepiness remain a subject of debate. This study investigated the effects of dynamically rising CO₂ concentrations on subjective sleepiness and neural oscillation patterns in a controlled environment. A within-subject repeated-measures experiment was conducted with 18 healthy university students exposed to CO₂ levels gradually increasing from a baseline of ~800 ppm to ~2000 ppm over a 40-min period. Subjective sleepiness was assessed using the Karolinska Sleepiness Scale (KSS), while electroencephalogram (EEG), heart rate (HR), and heart rate variability (HRV) were monitored continuously. Results indicate a significant increase in subjective sleepiness scores concurrent with rising CO₂ levels (p < 0.001). Power spectral density (PSD) analysis revealed that elevated CO₂ exposure significantly enhanced power in low-frequency EEG bands (δ, θ, and α), indicative of a transition from alertness to drowsiness. Specifically, α-band power peaked between 20 and 30 min (increasing by 0.15 uV² relative to the 0–10 min baseline), while θ and δ bands peaked earlier (10–20 min) and sustained elevated levels through 30 min. Topographic mapping identified the central, parietal, and occipital regions as the primary loci of this low-frequency activity. Additionally, HR and HRV measures showed upward trends, suggesting autonomic modulation. It is noted that low-frequency EEG power declined during the final 30–40 min interval, potentially reflecting physiological saturation or acclimatization. These findings provide objective neurophysiological evidence that dynamic CO₂ accumulation accelerates drowsiness onset, underscoring the necessity of optimized ventilation strategies in educational settings. However, these findings should be interpreted with caution due to the small sample size and the absence of a control group with constant CO₂ concentration. Future studies with larger, diverse samples and stable-concentration control groups are recommended to validate these trends. Full article

Critically ill patients are predisposed to developing cognitive dysfunction, excessive daytime sleepiness (EDS), and fatigue during their stay in the intensive care unit (ICU). Modafinil, a wakefulness-promoting agent, has demonstrated potential benefits in enhancing alertness, cognitive performance, and activity levels in various clinical populations. The present narrative review aims to systematically evaluate the existing literature regarding the administration of modafinil for the treatment of EDS and fatigue in the ICU context. A comprehensive literature search was performed using the Embase, MEDLINE, Web of Science, and Google Scholar databases, covering publications up to 20 June 2025. Studies investigating the use of modafinil to improve wakefulness in ICU patients were identified. A total of nine relevant studies were included, comprising two randomized controlled trials (RCTs), two case series, and five retrospective cohort studies (n = 950 patients). Four of these studies focused on patients with traumatic brain injury or post-stroke conditions, whereas the remaining studies addressed heterogeneous ICU populations. Preliminary evidence indicates that modafinil may enhance wakefulness in selected critically ill patients and potentially facilitate their participation in rehabilitative interventions, such as physical therapy. Nonetheless, robust conclusions regarding efficacy and safety remain limited by the small sample sizes and methodological constraints of the available studies. Consequently, further large-scale RCTs are warranted to elucidate the therapeutic role of modafinil in the management of EDS and hypoactivity among ICU patients. Full article

Background: Obstructive sleep apnea (OSA) impacts daytime alertness, mood, cognition, and quality of life (QoL). Initial alterations in these patient-reported outcomes (PROs) following CPAP therapy, along with their association with adherence and residual respiratory events, are only partially understood. Materials and methods: We conducted a retrospective, observational study from January 2024 to May 2025 involving adult patients with OSA. Standardized assessments were performed at baseline and at six months following the initiation of CPAP: Epworth Sleepiness Scale (ESS), WHOQOL-BREF, MoCA, DASS-21, GAD-7, and PHQ-9. The primary endpoint was the change in Patient-Reported Outcomes (PROs) and cognitive performance. The second was to identify associations between these improvements and the degree of adherence to CPAP therapy and residual AHI. Results: Seventy-two patients (median age, 57; 65.3% male) with moderate to severe OSA had a baseline median AHI of 34.5/h, ODI of 35.5/h, and a mean nocturnal SpO₂ of 92.4%. The initial burden was high: median ESS was 14, indicating excessive daytime sleepiness (EDS), present in 68.9%; median MoCA was 24, with 98.6% scoring below 26; median PHQ-9 was 7; median GAD-7 was 5; and 56.8% and 47.9% scored below 50 in physical and psychological domains of WHOQOL-BREF, respectively. After 6 months, group averages showed improvement: ESS decreased to 8.6 ± 3.7, with a 27.0% residual EDS; PHQ-9 was 7.1 ± 4.5; GAD-7 was 6.2 ± 4.1; and MoCA increased to 25.3 ± 2.7, although 48.6% still showed impairment. WHOQOL-BREF scores improved across domains: physical 58.7 ± 14.2, psychological 61.5 ± 13.6, social 63.2 ± 15.4, and environmental 59.8 ± 14.7, with fewer scores below 50 (physical 23.0%, psychological 18.9%). CPAP adherence was high, with a mean of 87.7% and a median of 95%, predicting a greater ESS reduction (p = 0.027) and showing a trend toward improvement in PHQ-9 scores (ρ = 0.218; p = 0.066). Residual respiratory indices at 6 months (AHI, ODI, SpO₂) did not correlate with PRO or cognitive scores at the same time point (all p > 0.16), nor with their change scores. Conclusions: Over the course of six months, CPAP therapy led to notable improvements in sleepiness, mood, anxiety, cognition, and overall quality of life. Nonetheless, many patients continued to face residual problems, mainly excessive daytime sleepiness (EDS) and cognitive challenges. The positive effects were more closely associated with how well patients adhered to the treatment than with remaining levels of residual AHI or ODI. Full article

This study investigated the effects of LED versus fluorescent task lighting on sleep quality and daytime functioning among office workers in a windowless environment. Using a within-subjects crossover design with 32 full-time employees, participants were exposed to both 4000 K LED and 4100 K fluorescent lighting conditions over two one-week periods. Subjective sleep quality and alertness were assessed through the Pittsburgh Sleep Quality Index (PSQI) and daily sleep diaries. Results indicated significantly better global sleep quality, improved subjective sleep assessments, and reduced daytime dysfunction under LED lighting conditions. While sleep duration did not significantly differ, a positive trend was observed favoring the LED condition. These outcomes are likely due to differences in spectral power distribution between the two light sources, particularly the continuous, blue-enriched spectrum of the LED lamp, which supports circadian regulation. The findings suggest that biologically supportive lighting—such as continuous-spectrum LEDs—can positively impact sleep and daytime performance, even in the absence of natural daylight. This research contributes to the growing field of circadian lighting and offers practical implications for architects, designers, and workplace managers aiming to enhance employee well-being and productivity in enclosed office environments. Full article

The rapid detection and confirmation of Suspicious Regions of Forest Fire (SRoFF) are critical for timely alerts and firefighting operations. In the early stages of forest fires, small flames and heavy occlusion lead to low accuracy, false detections, omissions, and slow inference in existing target-detection algorithms. We constructed the Suspicious Regions of Forest Fire Dataset (SRFFD), comprising publicly available datasets, relevant images collected from online searches, and images generated through various image enhancement techniques. The SRFFD contains a total of 64,584 images. In terms of effectiveness, the individual augmentation techniques rank as follows (in descending order): HSV (Hue Saturation and Value) random enhancement, copy-paste augmentation, and affine transformation. A detection model named SRoFF-Yolover is proposed for identifying suspicious regions of forest fire, based on the YOLOv8. An embedding layer that effectively integrates seasonal and temporal information into the image enhances the prediction accuracy of the SRoFF-Yolover. The SRoFF-Yolover enhances YOLOv8 by (1) adopting dilated convolutions in the Backbone to enlarge feature map receptive fields; (2) incorporating the Convolutional Block Attention Module (CBAM) prior to the Neck’s C2fLayer for small-target attention; and (3) reconfiguring the Backbone-Neck linkage via P2, P4, and SPPF. Compared with the baseline model (YOLOv8s), the SRoFF-Yolover achieves an 18.1% improvement in mAP@0.5, a 4.6% increase in Frames Per Second (FPS), a 2.6% reduction in Giga Floating-Point Operations (GFLOPs), and a 3.2% decrease in the total number of model parameters (#Params). The SRoFF-Yolover can effectively detect suspicious regions of forest fire, particularly during winter nights. Experiments demonstrated that the detection accuracy of the SRoFF-Yolover for suspicious regions of forest fire is higher at night than during daytime in the same season. Full article

Immune fitness is defined as the capacity of the body to respond to health challenges (such as infections) by activating an appropriate immune response to promote health and prevent and resolve disease, which is essential for improving quality of life. Thus, immune fitness plays an essential role in health, and reduced immune fitness may be an important signal of increased susceptibility for disease. Lifestyle factors such as increased levels of alcohol consumption have been shown to negatively impact immune fitness. The alcohol hangover is the most frequently reported negative consequence of alcohol consumption and is defined as the combination of negative mental and physical symptoms, which can be experienced after a single episode of alcohol consumption, starting when blood alcohol concentration (BAC) approaches zero. Significant correlations have been reported between hangover severity and both immune fitness and biomarkers of systemic inflammation. The concepts of immune fitness and alcohol hangover are further linked by the fact that the inflammatory response to alcohol consumption plays an important role in the pathology of the alcohol hangover. Moreover, immune fitness has been related to the susceptibility of experiencing hangovers per se. It is therefore important to investigate the interrelationship between immune fitness and the alcohol hangover, and to identify possible predictor variables of both constructs. This data descriptor article describes a study that was conducted with adults living in the UK or Ireland, evaluating possible correlates and predictors of immune fitness and the alcohol hangover. Data on mood, personality, mental resilience, pain catastrophizing, and sleep were collected from n = 1178 participants through an online survey. Herein, the survey and corresponding dataset are described. Full article

Sleep apnea-hypopnea syndrome (SAHS) is a respiratory disorder characterized by cessation of breathing during sleep, resulting in daytime somnolence and various comorbidities. SAHS encompasses obstructive sleep apnea (OSA), caused by upper airway obstruction, and central sleep apnea (CSA), resulting from lack of brainstem signaling for respiration. Continuous positive airway pressure (CPAP) therapy is the gold standard treatment for SAHS, reducing apnea and hypopnea episodes by providing continuous airflow. CPAP enhances sleep quality and improves overall health by reducing the risk of comorbidities such as hypertension, type 2 diabetes mellitus, cardiovascular disease and stroke. CPAP nonadherence leads to health deterioration and occurs due to mask discomfort, unsupportive partners, upper respiratory dryness, and claustrophobia. Technological advancements such as auto-titrating positive airway pressure (APAP) systems, smart fit mask interface systems, and telemonitoring devices offer patients greater comfort and enhance adherence. Future research should focus on new technological developments, such as artificial intelligence, which may detect treatment failure and alert providers to intervene accordingly. Full article

The relationship between daytime sleepiness and heart rate asymmetry (HRA) during the transition from evening to night is crucial for understanding autonomic regulation and its implications for alertness. This study aims to investigate how daytime sleepiness influences HRA dynamics from evening to night and how situational sleepiness correlates with HRA metrics. HRA metrics were calculated at 8 P.M., 9 P.M., and 10 P.M. in 50 participants, categorized into ‘Lower Normal’ and ‘Higher Normal’ daytime sleepiness groups based on Epworth Sleepiness Scale (ESS) scores. Situational sleepiness was assessed using the Karolinska Sleepiness Scale (KSS) and Stanford Sleepiness Scale (SSS). The results demonstrated that individuals with ‘Higher Normal’ daytime sleepiness exhibited lower HRA metrics at 10 P.M. compared to those with ‘Lower Normal’ daytime sleepiness, supporting the suggestion that higher daytime sleepiness correlates with reduced parasympathetic activity and diminished autonomic responsiveness. Significant negative correlations between situational sleepiness and HRA metrics were observed in the ‘Higher Normal’ group, particularly with the SSS. Therefore, increased daytime sleepiness affects HRA dynamics by decreasing parasympathetic activity and altering autonomic regulation at the beginning of the biological night (10 P.M.). These findings suggest potential applications for enhancing drowsiness detection and managing fatigue in safety-critical environments. Full article