This cross-sectional study aimed to assess differences in chrononutrition and sleep patterns, as well as social jetlag (SJL), eating jetlag (EJL), and preferred-based misalignments, among individuals with diabetes mellitus (DM) according to cognitive status. Cognitive function was screened using the Montreal Cognitive Assessment, with scores <21 indicating cognitive impairment. Chrononutrition and sleep patterns, as well as SJL, EJL, and misalignments, were assessed using the Chrononutrition Profile Questionnaire. Group comparisons were performed using t-tests or Mann-Whitney tests in crude analyses, followed by adjusted robust linear or quantile regression models according to variable distribution. Among the 365 participants, crude analyses suggested small differences between groups, with individuals with cognitive impairment showing earlier patterns (e.g. Cohen's d ranging approximately from 0.12 to 0.31 across variables). However, these associations were not sustained after adjustment for demographic, socioeconomic, and clinical covariates. No significant differences were observed for SJL or EJL in either crude or adjusted analyses. In conclusion, chrononutrition and sleep patterns, as well as SJL, EJL, and misalignment variables, did not differ according to cognitive status in individuals with DM after adjustment. Further longitudinal studies are needed to clarify these relationships.
Subjective sleepiness reflects the interaction between circadian and homeostatic processes and plays a critical role in cognitive functioning and everyday performance. While its increase across the evening is well documented, less is known about how individual sleep timing shapes its temporal dynamics under naturalistic conditions. The present study examined evening-to-night trajectories of subjective sleepiness in relation to self-selected bedtime. Data were collected using repeated assessments of sleepiness (Karolinska Sleepiness Scale and Stanford Sleepiness Scale) at 30-minute intervals. Bedtime was operationalized both categorically (early, middle, late groups) and continuously (minutes relative to 20:00). Linear mixed-effects models were applied to analyze the effects of time, bedtime, and their interaction. Subjective sleepiness increased significantly across the evening. Later bedtimes were associated with lower sleepiness levels on the KSS, whereas the effect for the SSS did not reach significance. A significant interaction between time and bedtime, driven by the late group, indicated that the rate of increase in sleepiness varied depending on sleep timing. These findings highlight the importance of considering individual sleep timing in understanding real-world sleepiness dynamics.
Background: Tennis requires repeated high-intensity efforts with brief recovery periods, placing significant demands on cardiac autonomic regulation and neuromuscular performance. Ramadan intermittent fasting alters sleep, nutrition, and hydration patterns, potentially affecting match responses, particularly in adolescents. Methods: Sixteen male International Tennis Federation (ITF) junior players completed a within-subject repeated-measures study during mid-Ramadan and 15 days post-Ramadan. Each performed a standardized two-set outdoor match under both conditions. Heart rate variability (HRV), countermovement jump (CMJ), blood glucose, hydration markers, and rating of perceived exertion were assessed at baseline (T0), between sets (T1), and post-match (T2). Sleepiness, chronotype, fatigue, and recovery were evaluated via validated questionnaires. Results: Match play reduced lnRMSSD (p < 0.001, eta p(2 )= 0.775) and increased LF/HF (p < 0.001, eta p(2)= 0.234), indicating sympathetic dominance. During Ramadan, parasympathetic activity was lower (p < 0.001, eta p(2)= 0.269), and CMJ performance was reduced (p = 0.010, eta p(2)= 0.085). Blood glucose showed a Period & times; Set interaction (p = 0.020,eta p(2) = 0.114). Sleepiness, fatigue, and perceived recovery were significantly impaired (p < 0.001). Conclusion: Ramadan intermittent fasting reduces vagal activity and impairs neuromuscular performance in adolescent tennis players. HRV-guided training, optimized nutrition, and sleep management may help mitigate these effects.
We investigated actigraphy-based associations between sleep efficiency (SEF) and circadian rhythm metrics of motor activity (MA), light exposure (LE), and wrist temperature (WT) in young adults (YA). A cross-sectional study included 187 YA (mean age 19.03 years; 132 women) across two seasons. Actigraphy data on MA, LE, blue light exposure (BLE), and WT were collected. Multivariable regression, adjusted for sex, age, season, and BMI, examined SEF associations with circadian metrics. Higher SEF was strongly predicted by greater MA relative amplitude (MA RA; beta = 0.458, p < 0.001), longer total sleep time (TST; beta = 0.402, p < 0.001), and earlier MA L5 timing (beta = -0.286, p < 0.001). Sex-specific effects were observed in females, who showed significant associations between higher SEF and earlier MA L5 onset (beta = -0.280, p = 0.002), earlier BLE L5 onset (beta = -0.303,p < 0.001), earlier WT acrophase (beta = -0.189, p = 0.031), greater BLE normalized amplitude (BLE NA; beta = 0.292, p = 0.002), greater WT amplitude (beta = 0.202, p = 0.031), and lower WT MESOR (beta = -0.312, p = 0.001), whereas similar associations were not significant in males.
Julia A. Sherman's The Neanderthal-Human Hybrid Is Us (2024) proposes an evolutionary model for bipolar disorder, viewing it as a behavioral fossil: depressive phases mimic quasi-hibernation, and mania echoes activity under optimal light. This integrates with circadian science, where light entrains clock genes and melatonin receptors, linking psychoemotional states to timed light and chronotherapy efficacy. Contemporaneous Arctic studies reveal seasonal photoperiod effects on melatonin, gene expression, metabolism, activity, and depression, highlighting population-specific variations. Neanderthal-derived alleles enrich circadian variants, biasing the chronotype toward morningness for ancient light regimes. Native Arctic residents exhibit phase delays and decoupled light-activity rhythms with genotype-dependent variability. These findings substantiate a genotype-environment mismatch hypothesis in modern settings, extending beyond mood to metabolic and endocrine traits. Clinically, they advocate for personalized light hygiene: morning bright light, evening dimming stratified by circadian variants for bipolar prevention and treatment. This synthesis bridges evolutionary psychiatry, genetics, and high-latitude data, urging biologically grounded reclassification of mental disorders and evolution-informed therapies.
Overnight work is associated with cardiometabolic disorders. While circadian misalignment is a recognized mechanism, the roles of socioeconomic status, physical activity (PA), sedentary behavior (SB), and stress in shaping cardiometabolic risk factors (CRFs) in the context of overnight work remain unclear. We analyzed 604 participants (302 overnight, 302 day workers; one-to-one age- and sex-matching) from the Korea National Health and Nutrition Examination Survey (2018-2021). Variables included work schedules, PA, SB, stress, and CRFs such as hypertension, HbA1c, lipid profiles, and fasting glucose. Analyses used chi-square tests, t-tests, and multinomial logistic regression. Overnight workers reported shorter weekday sleep (6.4 vs. 6.8 h, p < 0.001), longer work hours (39.7 vs. 36.9, p < 0.05), and higher HbA1c (5.8 vs. 5.7, p < 0.05). Odds of HbA1c >= 6.5% were greater (OR = 2.79, p < 0.01). They were also more likely to hold lower-income, blue-collar jobs (p < 0.001). PA, SB, and stress showed no significant differences. Despite similar lifestyle behaviors, overnight work adversely affects glycemic control, suggesting circadian disruption as a central driver of metabolic risk. This paradox emphasizes the importance of biological alignment and the need for interventions targeting sleep and metabolic health in overnight workers.
In insects, adult eclosion represents a classic circadian-regulated event, yet the roles of core clock genes in lepidopteran eclosion rhythms remain incompletely defined. In the silkworm Bombyx mori, previous studies have analyzed individual clock gene knockouts across different genetic backgrounds, which has hindered an integrated understanding of their roles in eclosion rhythm. Here, we systematically examined the roles of core clock genes in eclosion rhythm using knockout strains of period (per), timeless (tim), Clock (Clk) and cycle (cyc) generated in a single genetic background, the p50T strain. Under constant darkness, knockout of any core clock gene abolished endogenous eclosion rhythm, demonstrating a conserved role of these genes for rhythmic eclosion. In contrast, under light-dark conditions, distinct eclosion patterns emerged between knockouts of negative elements (per and tim) and positive elements (Clk and cyc), particularly with respect to their responses to lights-on. These results indicate that although core clock genes are universally required for eclosion rhythm in B. mori, the manifestation of knockout phenotypes depends on clock gene function and genetic background. Together, our findings provide a unified framework for understanding circadian regulation of eclosion in lepidopteran insects.
