Chronobiology International最新文献

Locomotor activity (LA) provides valuable insights into animal welfare and the temporal organization of physiology. This study evaluated the effects of rearing system (with mother vs. artificial), sex, and age (week 1 vs. week 3) on lamb LA and circadian rhythmicity. Lambs were fitted with triaxial accelerometers attached to neck collars, which were worn continuously for 7 d. LA was recorded and analyzed based on an ANOVA and cosinor rhythmometry. Activity (counts/min) was significantly (p < 0.001) higher in the day (154.3 ± 3.6) than they were at night (114.5 ± 2.9). Artificially reared lambs were significantly (p = 0.041) more active (159.3 ± 8.2) than were maternal-reared lambs (143.2 ± 7.3) in week 1, but not in week 3. In week 1, in the artificially reared group, females were significantly (p < 0.001) more active than were males (192.0 ± 8.2 vs. 126.5 ± 7.1). Cosinor analysis revealed an overall MESOR (Midline Estimating Statistic of Rhythm), of 131.7 ± 2.8, an amplitude of 36.4 ± 3.1, an acrophase around 15 h, and a robustness of 0.29. In conclusion, accelerometry was an effective tool for quantifying LA dynamics in lambs and can be useful in welfare assessment and precision management. LA was influenced by age and sex, with transient effects of rearing system in early life, and a maturation of circadian rhythmicity by week 3 of age.

Chronotype, which reflects an individual's preference for activity and sleep timing, has been associated with various chronic conditions, particularly the evening chronotype. Metabolic syndrome (MetS) is a cluster of metabolic abnormalities that collectively increase the risk of developing type 2 diabetes mellitus and cardiovascular diseases. Previous studies on chronotype and MetS have been inconsistent, and none has explored the longitudinal association between MetS and its components. Therefore, this study investigated these associations in middle-aged Japanese civil servants. We analyzed 2231 non-rotating, non-night shift workers (aged 29-69, 71.6% male) from the Aichi Workers' Cohort Study who participated in surveys in 2018 (baseline) and 2022 and were free of MetS at baseline. Participants were classified into morning, evening, or intermediate chronotypes using the shortened Morningness - Eveningness Questionnaire. MetS was defined according to the harmonized criteria for Japanese, based on waist circumference (≥85 cm for men and ≥90 cm for women), triglycerides, HDL cholesterol, blood pressure, and blood sugar levels. Over 4 y, 232 participants (10.4%) developed MetS, with a cumulative incidence rate of 9.9% in morning, 17.6% in evening, and 9.5% in intermediate types. Logistic regression analysis adjusted for sex, age, educational background, occupation, leisure-time physical activity, alcohol intake, sleep duration, smoking status, snoring, night-time awakening, sleep medication use, working hours, breakfast eating habit, and medication use for diabetes, hypertension, and dislipdemia, revealed that the evening type individuals had a significantly higher risk of MetS (OR: 2.30, 95% CI: 1.48-3.57) compared to intermediate types. In conclusion, evening chronotype was independently associated with a higher risk of developing MetS in middle-aged Japanese civil servants.

In Japan, irregular sleep patterns due to modern work styles have been linked to poor mental health. Prior studies relied mostly on subjective reports, limiting accuracy. We examined associations between daily sleep variability and depressive symptoms to explore how these factors are related in real-world occupational settings. The study involved 32 adults without physical or psychiatric disorders, insomnia, or shift-duty history who followed a Monday-to-Friday work schedule. Sleep was monitored at home for one week by a wearable electroencephalograph, and sleep indices were calculated. Questionnaires (Pittsburgh Sleep Quality Index [PSQI] and Beck Depression Inventory-II [BDI] were used to assess sleep and mental health. Bedtime, wake-up time, and time in bed were all delayed or extended before holidays. On holidays, light sleep duration increased significantly, and sleep latency was significantly prolonged. Greater bedtime variability was significantly associated with BDI. Median sleep time and rapid eye movement sleep duration were related to PSQI. Sleep disturbances were associated with variability in median sleep time, sleep efficiency, and mean light sleep. Absolute social jetlag related to PSQI and daytime dysfunction. These findings suggest that regular sleep patterns are crucial in occupational settings.

Diurnal preferences have been found to be associated with a range of adaptive and maladaptive personality traits, including the Big Five personality traits and the Dark Triad. However, no research to date has examined the relationship between morningness-eveningness and sadistic tendencies. According to the niche-specialization hypothesis, individuals with dark personality traits tend to be more active at night because darker environments can help reduce the likelihood of detection or punishment. Given that sadistic tendencies - defined as a person's inclination to derive pleasure from inflicting pain - are a typical dark trait, we anticipate that a nocturnal chronotype would positively correlate with everyday sadism. To test this hypothesis, we conducted two studies utilizing diverse populations and multiple measures of sadism. Study 1 utilized a convenient student sample and self-report questionnaires to provide initial evidence of a correlation between eveningness and sadistic tendencies. Study 2 aimed to validate and generalize these findings by recruiting a broader non-student adult sample and employing a behavioral paradigm less susceptible to self-presentation biases, thereby yielding more ecologically valid and objective evidence for the hypothesized relationship. Together, these findings offer the first empirical support for the association between a night-time chronotype and everyday sadism, thereby endorsing the niche-specialization hypothesis.

Sleep duration is a critical determinant of health that reflects the influence of biological, social, and environmental factors. Although geographic clustering of insufficient sleep in the United States has been described, seasonal and time-zone - related variation are less well understood. We analyzed the 2022 Behavioral Risk Factor Surveillance System (BRFSS) data from 416 731 adults, representing a weighted population of approximately 259 million. Using complex survey weights and general linear models adjusted for age and sex, we examined differences in self-reported sleep duration across months, time zones, and latitude bands. The overall mean sleep duration was 7.96 h. Monthly variation was modest and largely not statistically significant, with averages ranging from 7.82 hours in April to 8.13 h in January. In contrast, clear geographic differences emerged. Sleep duration varied significantly by time zone, with Pacific respondents reporting the longest sleep (8.37-8.56 h) and those in the Mountain and Hawaii time zones reporting the shortest (approximately 7.0-7.5 h). Adults in southern states reported consistently longer sleep than those in northern states, though the month × latitude interaction was not significant. Effect sizes were small across all models (ηp² range = 0.00002-0.00080; Cohen's d for latitude = 0.23), indicating modest but consistent geographic differences. Men slept less than women, and older adults reported slightly longer sleep. These findings suggest that geographic context, particularly time zone and latitude, plays a more consistent role than seasonality in shaping sleep duration in the U.S.

This study aimed to evaluate the validity and reliability of the Couples' Sleep Conflict Scale by adapting it to the Turkish population. This study is a methodological research conducted using a cross-sectional design. The cultural adaptation process of the scale was completed in a three-stage process consisting of language validity, content validity, and piloting. Exploratory and confirmatory factor analyses were applied to determine construct validity. Reliability analyses were performed with Cronbach's alpha internal consistency coefficient and test-retest analyses. According to the results of the exploratory factor analysis, the scale consists of 5 items and one sub-dimension in female, male, and total groups. According to confirmatory factor analysis, the scale items were determined to have an acceptable level of fit for each group. In the reliability analysis, high Cronbach Alpha values were obtained (Female: 0.838, Male: 0.827, and Total group: 0.835). In addition, high correlation values were observed in the test-retest analysis. The Couples' Sleep Conflict Scale is a valid and reliable measurement tool for assessing sleep conflict in married individuals in the Turkish population.

Daytime napping is a common compensatory behavior among university students experiencing irregular nocturnal sleep and heightened stress. We examined the associations between napping behavior, perceived stress, sleep quality, and daytime sleepiness in 757 undergraduate students (≥18 y) who completed an online questionnaire including sociodemographic data, the PSS-14, PSQI, and ESS. Chi-square, MANOVA, regression analyses and K-means clustering were applied (α = 5%). Women represented 68% of the sample and reported higher stress and daytime sleepiness and were more likely to nap (χ² = 11.991; p = 0.007). Higher proportion of women reported stress management as reason to nap (χ² = 8.84; p = 0.002). The frequency of napping was predicted by sex (OR = 0.65; CI = 0.48-0.87), PSS-14 (OR = 0.98; CI = 0.96-0.99), and Epworth sleepiness scores (OR = 1.12; CI = 1.09-1.16), while napping duration was predicted by age, Epworth sleepiness, PSQI sleep efficiency, and PSQI sleep disturbance scores (R2 = 0.03; p = 0.001). Three clusters emerged: Sleep disturbances (long sleep latency, higher stress, poorer sleep quality); Shorter naps (brief naps, better sleep quality, lower stress); and More naps (younger students with frequent naps and higher sleepiness). Despite limitations related to self-reported measures, online sampling, and the overrepresentation of students from health-related programs, our findings highlight the multidimensional role of napping in the regulation of stress and sleep.

Gestational diabetes mellitus (GDM) is associated with adverse metabolic and obstetric outcomes, yet its impact on behavioral, psychosocial, and chronobiological factors remains inadequately characterized. This prospective cohort study aimed to evaluate sleep quality, chronotype, daytime sleepiness, fatigue, perceived social support, and depressive symptoms in women with GDM using the Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS), Morningness-Eveningness Questionnaire (MEQ), Multidimensional Scale of Perceived Social Support (MSPSS), and Edinburgh Postpartum Depression Scale (EPDS). A total of 618 pregnant women (273 with GDM and 345 normoglycemic controls) were enrolled. Women with GDM exhibited significantly poorer sleep quality (p < 0.001), heightened fatigue severity (p < 0.001), and excessive daytime sleepiness (p < 0.001), lower perceived social support (p < 0.001) compared to controls. Evening chronotype was higher in the GDM group (p < 0.001), whereas controls were predominantly morning types. Although EPDS scores were elevated in GDM (p < 0.001), rates of clinically significant depression (EPDS ≥ 13) did not differ. Neonates of GDM mothers had higher birth weights (p < 0.001) and greater NICU admission rates (p < 0.001). In conclusion, GDM is associated with poorer sleep quality, greater fatigue, higher daytime sleepiness, evening chronotype, and reduced perceived social support, alongside adverse neonatal outcomes.

Anemia remains a significant public health concern, especially among young women. The SCARF (Study to Combat Anemia-Research for Female Students) study examined the association between daytime eating habits and anemia among Malaysian female university students. Using a validated chrono-nutrition questionnaire, meal patterns, dietary habits, and meal regularity were analyzed, while anemia status was determined by hemoglobin levels. Among 674 students, there were 44.4% Malay, 48.8% Chinese, and 3.4% Indian, with a mean age of 21.2 ± 1.5 y. About 59.3% were anemic, with a mean hemoglobin level of 11.6 ± 1.3 g/dL. Daytime meal-skipping habits were linked to significantly lower energy (p < 0.038), fat (p < 0.017), and folate intake (p = 0.003). Breakfast skipping was prevalent among anemic students (70%) compared to non-anemic students (61.3%; χ² = 5.51, p = 0.019). Irregular breakfast habits significantly increased anemia prevalence (79.8% vs. 20.3%; χ² = 5.10, p = 0.024). Lunch skipping three or more times weekly was a significant predictor of anemia, with an odds ratio of 1.62 (95% CI: 1.01-2.43; p = 0.04). These findings underscore the need for university health initiatives to promote regular breakfast and lunch habits, mitigating anemia risks and fostering long-term student health.