Chronobiology International最新文献

Pterostilbene (PTE) has emerged as a metabolic regulator with anti-obesity properties. However, the precise mechanism underlying these anti-obesity effects remains unclear. Given that the circadian clock machinery controls various biological processes, including metabolism, it remains unclear whether PTE impedes obesity by influencing the circadian clock. In the current study, an obese mouse model was established using a high-fat diet induction method, and the obese mice were treated with PTE. PTE was found to effectively improve dysregulated blood glucose, insulin, and lipid levels in obese mice. Moreover, PTE treatment mitigated lipid accumulation in the liver and peritesticular fat tissues of obese mice. Notably, qPCR results revealed that the disrupted phasic expression of circadian clock genes in obese mice was efficiently rescued by PTE consumption. These observations suggest that PTE partially inhibits obesity by normalizing the circadian clock. Our findings suggest a possible mechanism for the anti-obesity effect of PTE, highlighting its potential as a therapeutic agent to combat obesity.

The purpose of this study was to examine the effects of sleep inertia following naps of two durations on cognitive performance (reaction time and decision making), physical performance (countermovement jump (CMJ) and handgrip strength (HG)), and perceptual responses (i.e. sleepiness, fatigue, and readiness to perform). In a randomized, counterbalanced, crossover design, 17 physically active participants (9 males, 8 females, age: 23 ± 2 y) completed three conditions: no-nap (NN), a 25-min nap opportunity (N25), and a 90-min nap opportunity (N90). Naps were conducted in a controlled laboratory setting using a sleep pod. Nighttime sleep prior to each session was tracked using a wrist-worn actigraph, and sleep during naps was assessed using a forehead mounted EEG device. Following each condition, participants completed four 30-min test batteries within the first two post-nap hours (T1: 0-30 min post-nap, T2: 30-60 min post-nap, T3: 60-90 min post-nap, and T4: 90-120 min post-nap), starting at 15:00 h. Each session included assessments of sleepiness, fatigue, readiness to perform, cognitive function (psychomotor vigilance task and Simon task (ST)), and physical performance (HG and CMJ). All performance markers were impaired at T1 compared to the subsequent time points (p < 0.05) for both nap durations, with more pronounced sleep inertia after N90 (p < 0.05) for sleepiness, readiness to perform, HG, and accuracy during ST. However, most performance markers improved after both N25 and N90 at T3 (p < 0.05), with more improvement observed after N90 at T4 compared to NN and N25 in sleepiness, fatigue, reaction time during ST, and HG (p < 0.05). In conclusion, at least one hour is required for sleep inertia to dissipate following N25 and N90, with significant improvements in perceptual, cognitive, and physical performance observed at 1-2 h post napping.

Wearable technology is widely applied to rehabilitative assessment and care for patients with stroke. However, there is little information available on circadian rest-activity rhythm (RAR) parameters estimated from the data of wearable devices. To clarify the characteristics of RAR patterns in chronic stroke and specify factors associated with clinical assessments. Participants were recruited from stroke patients admitted to the convalescent ward of Nakadori Rehabilitation Hospital and elderly community-dwellers living in Akita Prefecture, Japan. The participants were instructed to wear the Actiwatch Spectrum Plus on the wrist of the non-paralyzed upper limb in the patient group or on the wrist of the non-dominant hand in the control group for 7 consecutive days. The nonparametric RAR parameters were calculated using the data from wearable devices, consisting of interdaily stability (IS), intradaily variability (IV), and relative amplitude (RA). The functional independence measure (FIM), clinical dementia rating (CDR), and oral function and nutritional assessment were used to evaluate clinical status in the patient group. Fifty-four participants were included for analysis, divided into the control group (n = 27) and the patient group (n = 27). As a result of binomial regression analysis, patients with chronic stroke were significantly associated with the IS × 100 value (odds ratio [OR] = 0.63; 95% confidence interval [95% CI], 0.42 to 0.95; p = 0.026), the IV × 100 value (OR = 1.04; 95% CI, 1.02 to 1.07; p = 0.001), and the RA × 100 value (OR = 0.88; 95% CI, 0.82 to 0.95; p < 0.001). Additionally, the IV value correlated with oral function and nutrition (r = -0.41, p < 0.05) within the patient group. Our results provide clinical characteristics of nonparametric RAR patterns in inpatients with chronic stroke. In light of the RAR characteristics in chronic stroke, oral function and nutritional status might have a potential impact on therapeutic interventions.

Many organisms are sensitive to lunar cycle-related changes, such as tidal fluctuations and variations in moonlight intensity. Marine organisms must synchronize their behavior to the underwater environment, which is more complex and variable than terrestrial habitats. Lunar-synchronized spawning refers to the monthly spawning cycle triggered by changes in phase of the moon and is especially common among temperate and tropical marine species. Corals, marine worms, and fish are well-known examples of organisms that spawn synchronously with lunar phases to improve fertilization success. Research over the past decade has provided insights into lunar-synchronized spawning, and studies of families such as Siganidae and Serranidae have begun to elucidate the underlying mechanisms in fish. Field investigations, particularly in tropical and subtropical waters, have shown that many species spawn during periods of the new or full moon. Species-specific spawning times may be determined genetically, with long-term environmental adaptation influenced by physicochemical and ecological factors. Even within the same species, spawning moon phases can vary by location. As lunar-synchronized spawning is regulated by moonlight cues, these geographical differences are likely driven by genetic variation in photoresponsiveness. Physiological experiments have further suggested that nocturnal light plays a role in both gonadal development and the timing of spawning in fish. Fish have been hypothesized to be able to predict moon phases for spawning by detecting temporal changes in moonlight intensity associated with the lunar cycle.

The objective of the current research was to examine the impact of 26 h of sustained wakefulness on endurance performance, cognitive abilities, and psychological state in young recreational runners. Thirteen male physical education students participated, in a randomized sequence, in two test sessions, following either a regular sleep night or complete sleep deprivation. During each session, participants took part in a 3-km running test on a 400-meter outdoor track. Cognitive assessments, including attention and reaction time tasks, as well as psychological evaluations (Feeling Scale and Hooper), were carried out before and after the run. Results indicated that sleep deprivation significantly increased the time to complete the 3-km run by 4.8% (p < 0.001). In addition, attention and reaction time were reduced by 14% (p < 0.001) and 15.3% (p < 0.05), respectively. Psychological measures also showed notable changes, with a 62.5% decrease in well-being (p < 0.01), a 31.5% increase in sleepiness (p < 0.001), a 16.5% rise in stress (p < 0.01), and a 12.7% increase in pain sensation (p < 0.05). In conclusion, 26 h of continuous wakefulness led to declines in attention, alertness, and psychological state, ultimately resulting in impaired 3-km running performance in young recreational runners.

         The daily melatonin rhythms and the effect of light pulse on this hormone were evaluated for Amazonian fish, Astronotus ocellatus and Brycon amazonicus. In experiment 1, fish were exposed to a 12h light:12h dark, and blood was sampled every 4h. In experiment 2, a light pulse was provided in the middle of the dark period for 1h. Melatonin peaked in the middle of the dark period in both species, and both showed an inverted ocular rhythm. The light pulse reduced plasma melatonin to daytime levels, while ocular melatonin remained unchanged. Thus, photic stimulation can be used as a physiological time cue.

The aim of this study was to investigate the effect of circadian rhythmicity (CR) on lower extremity strength and balance performance in 22 female athletes (19-24 y). Participants underwent isokinetic knee strength, Single Leg Hop Tests (SLHT), Y Balance Test (YBT), and isokinetic static/dynamic balance tests. All measurements were randomized and performed at 9:00, 14:00, and 19:00 to assess CR variation. In total, 3 angular strength, 5 jump, and 2 balance tests were analyzed. When comparing results across time zones, body temperature, isokinetic 60°/sec extension (Ext) strength, and several bipedal static balance parameters Forward-Backward Standard Deviation (SBFD), Average Forward-Backward Speed (AFBS), and Ellipse Area (EA)) showed statistical significance (p>0.05). No significant differences were found in other isokinetic strength tests, all SLHTs, Y balance, or dynamic balance tests (p>0.05). Significant CR effects on lower extremity strength were observed only in the 60 sec extension, with overall strength peaking at 14:00. Strength asymmetry remained similar across time points. These findings suggest that time-sensitive performance parameters like strength and static balance are influenced by CR, while balance and coordination parameters appear more stable. Accordingly, scheduling strength-based training during midday hours may optimize performance by leveraging CR-related variations.

Little is known about the relationship between sleep quality and quantity associated with mood, fitness, and menstrual cycle status in elite athletes. This longitudinal prospective cohort study explores these relationships in a French cohort of elite athletes in preparation for the Olympic Games. Self-reported sleep patterns, quality, mood, fitness and menstrual cycles were monitored daily via smartphone applications from February 2021 to February 2024, involving 108 athletes and 13 852 observations. Generalized Estimating Equations were used to evaluate associations between these variables across three menstrual cycle status groups (i.e regular, irregular, or under hormonal contraception). Sleep duration significantly correlated with self-reported sleep quality (β = 0.179), fitness (β = 0.241), and mood (β = 0.097) across all menstrual cycle status groups. Sleeping less than 8 h led to below-average scores in these parameters. Late bedtimes, especially after 11 PM for athletes with irregular cycles and after midnight for all groups, negatively impacted sleep quality, fitness, and mood. Athletes using hormonal contraception reported slightly longer sleep durations than those with regular (p < 0.04) or irregular cycles (p < 0.02). Despite individual variations, the cohort's average sleep duration (8.5 ± 1.2 h) aligned with recommended guidelines. Sleep patterns significantly influence mood and fitness similarly among elite athletes with a regular or irregular menstrual cycle or under hormonal contraception. Further studies are needed to clarify the role of hormonal status in sleep and its long-term implications for athlete health.

Circadian rhythms, typically synchronized with light-dark cycles, regulate key biological processes in surface organisms. In caves, however, the absence of light may disrupt these rhythms or promote alternative temporal patterns. We examined locomotor activity in two cave-dwelling scorpions with contrasting degrees of subterranean adaptation: Troglorhopalurus translucidus (troglobitic) and Troglorhopalurus lacrau (troglophilic). Activity was monitored under constant darkness (DD), light-dark (LD), and constant light (LL). Both species retained circadian rhythmicity, but with distinct responses: T. translucidus and T. lacrau exhibited diurnal activity under LD and changes in period under DD and LL. These findings demonstrate that circadian regulation persists in cave-adapted scorpions, but its expression is shaped by evolutionary pressures, highlighting the plasticity of biological clocks in light-deprived environments.

This study focused on taxi drivers to investigate the relationship between chronotype characteristics and daytime sleepiness, stress, fatigue, social relationships, car accidents, and general health. This cross-sectional study was conducted between September 2024 and January 2025. The sample comprised 229 taxi drivers from two bordering provincial centers in Türkiye. Data were analyzed using one-way ANOVA (with partial eta-squared), ch i-square, multiple regression, and logistic regression analyses. One in five participants (20.5%) had an evening chronotype. Participants with evening chronotypes experienced more daytime sleepiness (η² = .096), stress (η² = .182), fatigue (η² = .068), and were involved in more car accidents (Cramer's V = .19). They were also more disadvantaged in terms of social relations and overall health perception. The results showed that, when confounding factors were controlled, chronotype had an impact on daytime sleepiness, stress, fatigue, and social relationships. It was also found that work status and shift work were associated with increased fatigue and a higher incidence of car accidents. At the same time, work status was also related to high daytime sleepiness and negative social engagement. Chronotype characteristics have an impact on various variables related to traffic safety. Taxi drivers with an evening chronotype are particularly disadvantaged. The development of a chronotype-based work schedule can be considered a means to reduce levels of sleepiness, stress, and fatigue among taxi drivers, thereby improving their overall health and social relationships, and potentially preventing traffic accidents.