Chronobiology International最新文献

Spaceflight presents a multitude of challenges that disrupt astronauts' circadian rhythms, frequently leading to disturbed sleep and impaired cognitive functioning. This systematic review, conducted in accordance with PRISMA guidelines, synthesizes findings from 65 studies (including 47 included in the quantitative synthesis) to examine the multifactorial causes and consequences of circadian and sleep disturbances in space environments. Environmental stressors such as microgravity, radiation, confined spaces, noise, and altered light-dark cycles are critically evaluated alongside biological mechanisms including metabolic alterations, reduced melatonin secretion, and dysregulation of key circadian clock genes (PER2, BMAL1). These disruptions contribute to sleep disorders such as insomnia, sleep fragmentation, and reduced sleep efficiency. The resulting sleep deficits are shown to negatively impact cognitive domains including attention, decision-making, memory, spatial awareness, and problem-solving. This review further highlights the need for effective, evidence-based countermeasures to mitigate sleep disturbances and preserve cognitive performance during long-duration missions.

Subjective memory complaints (SMCs) are commonly observed among community-dwelling older adults. This study aimed to investigate the association of sleep and circadian rest-activity rhythm (RAR) in elderly individuals with coexisting frailty or pre-frailty alongside SMC. Participants aged 75 y and older were recruited from community settings in Akita Prefecture. Data collection was conducted between April 2023 and August 2025. RAR parameters were derived from wrist-worn Actiwatch Spectrum Plus devices, worn on the non-dominant wrist for 7 to 14 consecutive days. A total of 95 participants were included in the final analysis and categorized into four groups: robust (n = 36), SMC only (n = 28), SMC plus pre-frailty (n = 27), and SMC plus frailty (n = 4). Multiple logistic regression analyses were performed to examine associations between group status and clinical variables. In the final model, adjusted for age, gender, education, grip strength, Trail Making Test version A (TMT-A), and M10/100, the presence of SMC was significantly associated with higher scores on the Geriatric Depression Scale-15 (GDS-15) (odds ratio [OR] = 1.55; 95% confidence interval [CI]: 1.19-2.03; p = 0.001). Similarly, the SMC coexisting pre-frailty status was significantly associated with GDS-15 scores (OR = 1.73; 95% CI: 1.30-2.31; p = 0.0002), and a significant association was also observed with IV × 100 (OR = 1.04; 95% CI: 1.00-1.09; p = 0.044). The co-occurrence of SMC and pre-frailty appears to be associated with elevated depressive symptoms and fragmented RAR patterns in individuals aged 75 y and older. Further research is warranted to clarify the relationship between disrupted RAR and the combined presence of SMC and frailty.

Birds have a complex system of interacting central clocks, including SCN, pineal gland and retina. The pineal gland and retina possess the functions of sensing light, generating circadian oscillation, and secreting melatonin, making them crucial components for regulating circadian rhythms in birds. BMAL1 and CLOCK proteins form a heterodimer, playing a central role in regulating melatonin secretion and other downstream genes. However, the effect of monochromatic light on the expression of BMAL1 and CLOCK in the chick retina and melatonin, and whether the effect of monochromatic light on the retinal circadian clock depends on the regulation of the pineal gland have yet to be clarified. The present study raised newly hatched chicks under monochromatic white, red, green, and blue light for 14 days, with LD12:12 photoperiod, while the pinealectomy and sham operation were performed on the fourth day. ELISA, Western blot, immunohistochemistry, and immunofluorescence experiments were performed. The results showed that under different monochromatic lights, pinealectomy did not have any significant effect on the expression levels of BMAL1 and CLOCK proteins in the chick retina, neither altered the presence or absence of circadian rhythms of plasma melatonin, but significantly reduced the plasma melatonin levels. Monochromatic green light promotes the circadian expression of BMAL1 and the daily average expression level of CLOCK, as well as the secretion of melatonin. The BMAL1 and CLOCK proteins are mainly expressed in the photoreceptors of the retina. Therefore, chick retina is a circadian pacemaker that is relatively independent from the pineal gland, and monochromatic green light promotes the synthesis and secretion of melatonin by promoting the expression of the retinal BMAL1 and CLOCK in chicks.

Chrononutritional interventions, such as time-restricted feeding (TRF), have been extensively studied with an emphasis on metabolism. However, the evidence regarding the effects of TRF on sleep health remains fragmented and inconclusive. To add to the information in this area and given the potential connections between sleep and metabolic health and the diversity of TRF interventions, a meta-analysis of the effect of TRF on sleep will help to increase the level of evidence available on this topic. This meta-analysis presents the effects of TRF, including a specific type of TRF (Ramadan), on sleep, measured by subjective and objective methods. The review was conducted according to the PRISMA 2020 guidelines and registered in the PROSPERO database (CRD42020181264). The search was conducted in the databases MEDLINE, Scopus, Web of Science, EMBASE, LILACS and Cochrane CENTRAL until March 2024. The article selection process was conducted in two stages: first, the titles and abstracts were screened, and then the full texts were analyzed. The outcomes evaluated were self-reported total sleep time (TST), subjective sleep quality measured by the global score on the Pittsburgh Sleep Quality Index (PSQI), and objective TST measured by polysomnography or actimetry. The final sample included 51 articles from 17 countries, published between 2001 and 2023. The results showed that TRF decreased self-reported TST and impaired subjective sleep quality, as evidenced by an increase in the global score of the PSQI. Ramadan fasting significantly decreased TST and non-Ramadan TRF studies showed an overall increase in TST, suggesting that the timing and structure of dietary interventions play a crucial role in sleep health. Regarding PSQI, Ramadan fasting increased the global score, indicating poor subjective sleep quality. There was no statistically significant difference in the global PSQI score between the TRF and control groups in non-Ramadan fasting studies. Our results suggest that TRF has an effect on self-reported sleep duration and quality that depends on the type and duration of dietary restriction. Further randomized and controlled intervention studies are needed to better understand this relationship.

This study explores the relationship between loneliness, sleep chronotype (SC), and depressive symptoms (DS) in Chinese college students, with a focus on SC's mediating role. A cross-sectional survey was conducted with 1,079 college students, using validated instruments to assess loneliness, SC, and DS. Pearson correlation analysis revealed a significant positive correlation between loneliness and DS (r = 0.549, p < 0.01) and a negative correlation between SC and both loneliness (r = -0.177, p < 0.01) and DS (r = -0.206, p < 0.01). Structural equation modeling (SEM) indicated that SC partially mediated the relationship between loneliness and DS, with a significant indirect effect (β = 0.016, 95% CI: 0.003-0.035, p = 0.013). The findings suggest that college students with higher loneliness are more likely to have an evening-type sleep pattern, which exacerbates depressive symptoms. This study emphasizes the role of sleep-wake preference as a potential target for interventions to alleviate the effects of loneliness on adolescent depression, contributing to mental health prevention and treatment strategies.

β-Sitosterol (BS) is a phytosterol that may contribute to circadian and metabolic regulation through multiple predicted mechanisms. Using network pharmacology, gene expression profiling, and microbiome analysis, this study suggests that BS could interact with nuclear receptors (PPARγ, PPARα, RORα, RORγ) and potentially influence CLOCK:BMAL1 transcriptional rhythms in peripheral tissues. BS was also predicted to be associated with PER2-related feedback and the synchronization of gluconeogenic and lipogenic pathways with the light-dark cycle. In addition, computational and preclinical evidence indicates that BS may influence the gut microbiome, supporting short-chain fatty acid-producing bacteria, intestinal barrier integrity, and inflammatory balance. Limited preclinical findings further suggest a potential role for BS in mitigating circadian misalignment and insulin resistance, with possible implications for lipid homeostasis. Future clinical studies are warranted to investigate BS supplementation across different chronotypes and dietary conditions in order to evaluate its chronotherapeutic potential. While the findings are promising, they remain preliminary, and human validation is essential to determine dosing strategies and therapeutic relevance. This study, therefore, highlights BS as a candidate compound with potential relevance to circadian disruptions and metabolic disorders, pending further experimental confirmation.

Shift work, particularly night shifts, disrupts circadian rhythms and contributes to various adverse health outcomes. However, the degree of individual adaptability varies considerably, suggesting complex interactions between genetic factors, such as chronotype, and shift work exposure. To explore these interactions, we conducted a bidirectional Mendelian randomization (MR) analysis using genome-wide association study (GWAS) data from European populations. We examined causal associations between chronotype and shift work patterns (limited, intermittent, regular). A significant inverse causal effect was identified for intermittent shift work influencing morning chronotype (IVW: β =-0.0032, SE = 0.0013, p = 0.0114; weighted median: β = -0.0041, SE = 0.0018, p = 0.0213). This suggests that intermittent shift work may impact circadian preferences genetically linked to chronotype. Conversely, genetic predisposition toward morningness exhibited a notable but statistically non-significant inverse relationship with regular shift work. Our findings highlight that shift work and chronotype interact bidirectionally, potentially via circadian disruption and melatonin dysregulation. These insights could inform targeted health protection strategies for shift workers. Further studies should confirm these genetic interactions across diverse populations and clarify the underlying chronobiological mechanisms to enhance occupational health policies.

Modern lifestyles increasingly involve indoor activities, which entails considerations for ensuring sufficient light exposure for circadian entrainment and overall well-being. At higher latitudes, where daylight hours are limited in winter, environmental factors such as snow cover may enhance light exposure through its high reflectance. This study investigates the potential effects of snow cover on human biology and behavior in an urban population in Uppsala (59.9° North), Sweden between December and February. Forty-five individuals were monitored for 1 week when there was snow cover and another week without snow cover by using actigraphy, diaries, and collection of morning saliva melatonin samples. Our findings suggest that indoor dwellers at northern latitudes struggle to obtain adequate natural light exposure to sustain mood and alertness during December and January. However, snow cover increases morning light exposure, lowers melatonin levels, and enhances alertness and activity throughout the day. On the other hand, snow cover had minimal influence on sleep-wake cycles, sleep quality, and daytime mood ratings.

Light pollution has become a potential health risk factor worldwide. It exerts its effect by disrupting the circadian rhythms, which is linked to adverse health outcomes, including mood disturbances. Caffeine can influence alertness and sleep patterns, while probiotics may affect circadian regulation through the gut-brain axis. Consequently, this study aimed to investigate the potential role of caffeine (30 mg/kg) and probiotics (1 billion colony forming units (CFUs) per day) in alleviating biochemical alterations associated with depression following constant light exposure. Neurotransmitters, glutathione (GSH), malondialdehyde (MDA), and melatonin (MEL) were estimated in the cerebral cortex and the hypothalamus. Hormonal levels of MEL and corticosterone (CORT) were measured in serum samples. LL exposure reduced serotonin (5-HT) levels. It also induced alteration in MEL and CORT rhythmicity. However, caffeine enhanced 5-HT and MEL content and modulated the temporal profile of MEL. Probiotics restored corticosterone and melatonin level to a temporal pattern like controls. Additionally, both treatments reduced MDA levels and enhanced GSH content. Coadministration of caffeine and probiotics reduced 5-HT levels. In conclusion, caffeine and probiotics could modulate biochemical alterations caused by constant light exposure, which is known to disrupt circadian rhythm in rodents, making them apropriate antidepressants.