Search Results (86)

Obesity is a multifactorial condition that influences metabolic, endocrine, inflammatory, circadian, and behavioral systems. These disruptions can adversely affect the initiation of lactogenesis II—the critical process marking the onset of copious milk secretion following childbirth. In mothers with obesity, prolonged inflammation within the mammary gland, a blunted hormonal response (notably of prolactin), altered progesterone and estrogen dynamics, high leptin levels, and misaligned circadian rhythms contribute significantly to delayed lactogenesis. In addition, mechanical difficulties and psychological factors further hinder effective breastfeeding. This report synthesizes evidence from human epidemiological studies and animal models that elucidate the diverse mechanisms linking maternal obesity to delayed lactogenesis. We review the role of obesity-associated inflammatory mediators in impairing mammary tissue remodeling, the endocrine aberrations that impair lactogenic signaling, the consequences of circadian disruption on hormonal rhythmicity, and the behavioral influences that challenge effective breastfeeding. Finally, we discuss the clinical implications of these findings and propose future research directions targeting endocrine modulation, anti-inflammatory therapy, circadian interventions, and enhanced lactation support strategies for mothers with obesity. Full article

Short sleep has been linked to overweight, possibly via alterations in appetite-regulating hormones, but findings are inconsistent. Sex differences may contribute to this variability. This systematic review examines whether sex modifies the hormonal response to sleep curtailment. PubMed, Embase, Cochrane, CINAHL, and PsycINFO were searched for English-language experimental studies published before December 2024. Included studies assessed at least one appetite-regulating hormone and presented sex-specific analyses. Studies involving health conditions affecting sleep, circadian misalignment, or additional interventions were excluded. Risk of bias was assessed using the Revised Cochrane Risk-of-Bias tool (RoB 2). Eight studies (n = 302 participants) met inclusion criteria. A narrative synthesis of the findings was conducted for each hormone separately to explore potential differences in their response to sleep restriction. Some sex-related variations in hormonal response to sleep restriction have been observed for leptin (four studies, n = 232), insulin (three studies, n = 56), glucagon-like peptide-1 (one study, n = 27), ghrelin (three studies, n = 87), adiponectin (two studies, n = 71) and thyroxine (two studies, n = 41). However, findings were inconsistent with no clear patterns. No sex-related differences were found for glucagon or PYY, though data were limited. Findings suggest sex may influence hormonal responses to sleep restriction, but inconsistencies highlight the need to consider factors such as BMI and energy balance. Well-controlled, adequately powered studies are needed to clarify these effects. Full article

Circadian rhythms are intrinsic, with roughly 24 h oscillations that coordinate many physiological functions and are increasingly recognized as key determinants of human health. When these rhythms become misaligned, there is an increased risk for neurodegenerative and psychiatric disorders, metabolic syndrome, sleep disturbances, and even certain cancers. The hormones, melatonin that rises in the evening and cortisol that peaks shortly after awakening, represent crucial biochemical markers of the circadian phase. This review systematically evaluates contemporary techniques for quantifying melatonin and cortisol, comparing biological matrices (blood, saliva, urine) alongside analytical platforms. Special focus is placed on two clinically informative markers: Dim Light Melatonin Onset (DLMO) and the Cortisol Awakening Response (CAR). We compared immunoassays with liquid chromatography tandem mass spectrometry (LC MS/MS), highlighting differences in sensitivity, specificity, and laboratory feasibility. Potential confounders, including ambient light, body posture, and exact sampling times—are discussed in detail, to show the capacity of providing the most reliable results. By emphasizing the need for standardized protocols and controlled sampling conditions, this review provides essential guidance for researchers and clinicians aiming to assess the circadian biomarkers melatonin and cortisol with precision since they can be used in clinical practice as diagnostic and prognostic tools for assessing numerous pathologies. Full article

Circadian rhythms govern cellular metabolism, redox balance, and endocrine signaling in numerous tissues. However, chronic disturbance of these biological rhythms, mediated by modern lifestyle factors including shift work, sleep irregularity, and prolonged light exposure, has been increasingly associated with oxidative stress, metabolic dysregulation, and the pathogenesis of chronic diseases. This review discusses recent mechanistic advances that link circadian misalignment with tissue-specific metabolic reprogramming and impaired proteostasis, focusing on metabolic inflammation and associated pathologies. Emerging work reveals a close interdependence between the circadian clock and proteasome-mediated protein turnover and highlights this interplay’s importance in maintaining redox homeostasis. Furthermore, circadian modulation of the activity of the inflammasome complex is suggested to represent an important, but largely unexplored, risk factor in the pathobiology of both malignancy and metabolic syndrome. Recently, researchers have proposed them as novel endocrine regulators of systemic energy balance and inflammation, with a focus on their circadian regulation. In addition, the emerging domains of chrono-epigenetics and tissue-specific programming of the clock pathways may serve to usher in novel therapies through precision medicine. Moving ahead, circadian-based therapeutic approaches, including time-restricted feeding, chronopharmacology, and metabolic rewiring, have high potential for re-establishing physiological domain homeostasis linked to metabolic inflammation pathologies. Elucidating this reciprocal relationship between circadian biology and cellular stress pathways may one day facilitate the generation of precise interventions aiming to alleviate the health burden associated with circadian disruption. Full article

Background and Objectives: Shift work and night work are common among emergency physicians. It is necessary to provide continuous care to patients, especially with acute diseases, including throughout the night. Literature studies show that shift and night workers have an altered light exposure, timing of sleep and intake of food. The consequence of this desynchronization with the biological clock can lead these workers to be more exposed to developing some acute and chronic health conditions. In particular, the alteration of the sleep–wake cycle, fatigue, the shortened sleep duration and the misalignment of the body’s hormone production is a codified risk factor of gut dysbiosis that can lead to acute and chronic diseases, also gastrointestinal ones. the aim of this narrative review is to collect and summarize evidence about the association between the disruption of the circadian rhythm, sleep and food timing alterations, gut dysbiosis and the risk of gastrointestinal diseases among shift and night workers. Materials and Methods: we searched for evidence about the association of shift and night work, dysbiosis, gut microbiota and gastrointestinal diseases among shift workers in healthcare settings. Results: shift work and night work are associated with a higher risk of diseases, an inflammatory state and the alteration of the gut microbiota composition; but definitive data are still inconsistent. Conclusions: Until now, obtaining conclusive results in regard to the relationship between shift work, the gut microbiota and the increased risk of gastrointestinal disorders has been particularly complex and not yet feasible. More confirmatory studies are needed to better characterize risk factors and realize preventive measures. Full article

The circadian clock orchestrates nearly every aspect of physiology, aligning metabolic processes with environmental cues, such as light and food intake. While the central pacemaker in the suprachiasmatic nucleus synchronizes peripheral clocks across key metabolic tissue, feeding behavior emerges as the dominant cue for peripheral clock alignment. This interaction reveals a crucial link between circadian biology and metabolism. Disruption of these processes, whether from shift work, irregular eating patterns or lifestyle misalignment, has been strongly associated with metabolic disorders, including obesity, insulin resistance and cardiometabolic diseases. Within the field of chrononutrition, strategies, such as time-restricted feeding (TRF), have gained attention for their potential to restore circadian alignment and improve metabolic health. However, translational gaps persist, as most mechanistic insights are derived from nocturnal murine models, limiting their applicability to diurnal human physiology. Moreover, human studies are confounded by interindividual variability in chronotype, behavioral patterns, and dietary compliance. This review explores the molecular underpinnings of zeitgeber signals and critically assesses the translational barriers to implementing chrononutrition across species. By integrating insights from both preclinical and clinical research, we aim to refine the potential of circadian-based dietary interventions for metabolic disease prevention and personalized nutrition. Full article

Background/Objectives: Shift workers face higher risks of impaired glucose metabolism due to irregular eating habits and circadian misalignment. Time-restricted eating (TRE) could improve glucose metabolism by aligning food intake with the circadian clock, but its effectiveness remains unclear. Methods: Ten electronic databases (PubMed, EMBASE, Cochrane Library, CINAHL, PsycINFO, Scopus, Web of Science, ProQuest Dissertations and Theses, Science.gov, and ClinicalTrials.gov) were searched from journal inception to September 2024. Only randomized controlled trials (RCTs) involving shift workers were included. Meta-analyses with sensitivity analyses were conducted using a random-effects model to pool glucose metabolism and sleep outcomes, with heterogeneity and quality assessments performed. Results: Six RCTs were included. TRE demonstrated positive but non-significant effects on glucose metabolism outcomes: fasting blood glucose (weighted mean difference [WMD]: −0.02 mmol/L, 95% confidence interval [CI]: −0.13 to 0.10, I² = 0%), fasting blood insulin (WMD: −5.77 pmol/L, 95% CI: −85.62 to 74.08, I² = 92%), HOMA-IR (WMD: −0.50, 95% CI: −2.76 to 1.76, I² = 82%), 2 h postprandial glucose (WMD: −0.65 mmol/L, 95% CI: −3.18 to 1.89, I² = 86%), total sleep time (g = 0.07, 95% CI: −0.23 to 0.37, I² = 0%), and sleep efficiency (g = −0.05, 95% CI: −0.63 to 0.53, I² = 62%). Sensitivity analyses yielded similar findings, and overall certainty of evidence was rated ‘very low’. Conclusions: While TRE shows potential for improving the glucose metabolism in shift workers, current evidence remains inconclusive due to small sample sizes and study limitations. Future research should prioritize well-powered TRE RCTs in shift workers that adhere to a 6–10 h eating window. Incorporating early-TRE schedules with sleep hygiene may optimize metabolic outcomes, with circadian biomarkers analyzed to better elucidate the mechanistic pathway implicated. Full article

In mammals, the core molecular clock genes and the overall circadian system are established during early development; during this critical period of development, maternal metabolic condition plays a major role in programming temporal metabolic regulation. Therefore, this study aimed to evaluate the effects of the chronic maternal intake of a high-fat and high-carbohydrate diet (HFCD) before and during pregnancy, in addition to a challenge with HFCD during adulthood, on offspring diurnal metabolic profile and on clock gene expression in central and peripheral circadian oscillators. The HFCD offspring and/or those exposed to the metabolic challenge exhibited alterations in the temporal profiles of analytes associated with both the carbohydrate and lipid metabolisms, as well as markers associated with liver and kidney damage, ranging from phase changes in rhythmicity or, in some cases, to the complete loss of 24 h variations. At the molecular level, the expression of clock genes (Per1, Cry1, Bmal1, and Clock) in the central and peripheral oscillators showed differential susceptibility to undergoing changes in their abundance. Our data indicate that maternal HFCD during pregnancy, a second exposure in adulthood, or both result in the long-term misalignment of the diurnal rhythm’s metabolic and damage markers; these changes are possibly associated with alterations in the core molecular circadian clockwork. Full article

Insufficient sleep and circadian misalignment increase inflammatory agents. This triggers neuroinflammation and can result in health issues including depression, dementia, lifestyle-related diseases, and industrial accidents. Lactoferrin (LF) confers neuroprotective effects, which are derived from its anti-inflammatory, antioxidant, and iron metabolic properties; however, its roles in acute neuroinflammation and circadian rhythm disruption are yet to be elucidated. Therefore, we aimed to test the effects of LF on rat neuroinflammation and sleep and jetlag in humans. Rats received 7 days of an oral liposomal bovine LF (L-bLF) or vehicle followed by polyriboinosinic:polyribocytidylic acid (poly I:C) peritoneal injections (n = 5–6). Compared with the rats given poly I:C only, the rats given L-bLF and poly I:C had lower Il1b, Tnf, Casp1, Nfe212, Gclm, and Sod2 expression in the hippocampus. This open-label pilot study was carried out on tour conductors performing regular international tour responsibilities, and the data were compared between the initial tour without L-bLF intake and the subsequent tour with L-bLF intake. In the tour with L-bLF intake, L-bLF administration started from one week before the trip and was continued during the trip. In both periods, the tour conductors experienced limited sleep; however, both subjective and objective sleep quality was significantly better with the oral L-bLF intake than without. Overall, we found that prophylactic L-bLF supplementation reduced neuroinflammation in rat hippocampi and improved sleep quality and jetlag in tour conductors. Full article

The circadian rhythm of cortisol, a key hormone essential for maintaining metabolic balance and stress homeostasis, is profoundly disrupted by night-shift work. This narrative review examines the physiological mechanisms underlying cortisol regulation, the effects of shift work on its circadian rhythm, the associated health risks, and potential mitigation strategies. Night-shift work alters the natural secretion pattern of cortisol, leading to dysregulation of the hypothalamic–pituitary–adrenal axis, which in turn can contribute to metabolic disorders, cardiovascular diseases, and impaired cognitive function. Understanding the physiological pathways mediating these changes is crucial for developing targeted interventions to mitigate the adverse effects of circadian misalignment. Potential strategies, such as controlled light exposure, strategic napping, and personalized scheduling, may help to stabilize cortisol rhythms and improve health outcomes. This review aims to provide insights that can guide future research and inform occupational health policies for night-shift workers by addressing these challenges. Full article

Despite extensive research on the effects of sleep restriction on adolescent health, the field lacks experimental methods to study the health effects of mistimed sleep, which is also common among adolescents. This paper describes a novel 3-week experimental protocol that was designed to compare sleep restriction, like what many adolescents experience on school nights, against sleep that meets the recommended duration but is timed to be relatively aligned or misaligned with their circadian phase. Healthy 14–18-year-olds, classified as early (“Lark”) and late (“Owl”) chronotypes, entered a six-night chronotype-aligned stabilization condition, followed by five nights of sleep restriction, a return to the stabilization schedule, and five nights of healthy sleep duration (HS). During HS, participants were randomly assigned to early-to-bed versus late-to-rise arms, intended to align with or misalign with their circadian phase. Actigraphy monitored sleep, and weekly dim-light melatonin onset (DLMO) assessed circadian phase. Analyses confirmed that the protocol met five key validation metrics related to differential attrition, sleep timing, circadian phase, and experimental induction of HS that is timed to be relatively aligned vs. misaligned with circadian phase. This protocol appears useful for future research into how misaligned sleep patterns, which occur regularly for many adolescents, may impact health. Full article

Circadian misalignment, due to shiftwork and/or individual chronotype and/or social jetlag (SJL), quantified as the difference between internal and social timing, may contribute to cardiovascular disease. Markers of endothelial dysfunction and activation of the coagulation system may predict cardiovascular pathology. The present study aim was to investigate the effects of shift work, SJL, and chronotype on endothelial function and coagulation parameters. One hundred female nurses underwent endothelial function testing using the EndoPAT and blood sampling for coagulation markers, repeated at 06:00–9:00 and 18:00–21:00. We found that compared with day workers, endothelial function and fibrinogen levels were lower (p = 0.001, p = 0.005, respectively) and the procoagulant parameters of plasminogen activator inhibitor-1 (PAI-1) and heparanase level and activity were higher amongst shift workers (p = 0.009, p = 0.03, p = 0.029, respectively). High SJL was associated with lower endothelial function (p = 0.002) and higher PAI-1, heparanase procoagulant activity, heparanase level, and D-Dimer level (p = 0.004, p = 0.003, p = 0.021, p = 0.006, respectively). In the late chronotype, PAI-1 and heparanase procoagulant activity were higher than in the early chronotype (p = 0.009, p = 0.007, respectively). Diurnal variation was found for PAI-1, von-Willebrand factor (vWF), heparanase, and heparan-sulfate with higher levels in the mornings. The correlation between shift/day workers and SJL or chronotype was moderately strong, indicating that SJL and chronotype are independent factors. In conclusion, findings suggest endothelial impairment and increased thrombotic risk in nurses working in shifts or with high SJL or late chronotype. The thrombotic risk is increased in the morning independent of circadian misalignment cause. These findings strengthen the importance of the alliance to the biological daily rhythm in daily life. Further research is needed to evaluate inhibitors of heparanase to attenuate the thrombotic risk in individuals with circadian misalignment. Full article

Background/Objectives: Studies have highlighted the impact of work and school schedules on food preferences, suggesting that individuals’ dietary choices may change during the week to align with their daily routines. Despite the variation in food composition in the population, there is no evidence identifying differences in food intake times and composition across the days of the week in urban/rural locations. Thus, the study’s aim was to identify weekday vs. weekend differences in food intake times and composition (calories) between urban and rural areas. Methods: Data from 5770 participants (aged 18–59 years) were analyzed from the National Household Budget Survey (POF-IBGE) consisting of two distinct food diary records (weekday + weekend) per individual, including area (urban or rural) information in Brazil. Results: During weekdays, the time of the first food intake was significantly earlier, and the last food intake time was significantly later compared to weekends, resulting in a longer eating window on weekdays in both urban and rural areas. People living in urban areas exhibited delayed first and last food intake times, resulting in later caloric and eating midpoints compared to people living in rural areas. Periodogram analysis detected weekly rhythmicity (7 days) at the time of the first food intake and the length of the eating window in urban residents. Conclusions: The observed 7-day rhythmic pattern of food intake in urban areas, driven by work and school schedules, underscores the influence of urbanization on dietary timing and composition. In contrast, rural areas exhibited more stable and earlier eating patterns. These results emphasize the need for public health interventions to address meal timing and circadian alignment, particularly in urban settings, to mitigate the risk of metabolic disorders and improve overall health outcomes. Full article

The chronotype, the personal predisposition towards morning or evening activities, significantly influences health conditions, sleep, and eating regulations. Individuals with evening chronotypes are often at a higher risk for weight gain due to misalignment between their natural tendencies of functioning and social schedules, resulting in insufficient sleep, disruptions in eating habits, and decreased physical activity levels. Often, impaired glucose tolerance and changes in melatonin, adiponectin, and leptin secretion, along with alterations in the clock gene functions in subjects with evening preferences, may be predisposed to obesity. These disturbances contribute to metabolic dysregulation, which may lead to the subsequent onset of obesity complications, such as hypertension, type 2 diabetes, sleep apnea, and liver diseases. Targeting critical components of the circadian system and synchronizing people’s chronotypes with lifestyle conditions could deliver potential strategies for preventing and treating metabolic disorders. Thus, it is recommended to take a personalized chronobiological approach to maintain a normal body weight and metabolic health. Nevertheless, future studies are needed to identify the clear mechanisms between the chronotype and human health. This article provides a narrative review and discussion of recent data to summarize studies on the circadian rhythm in the context of obesity. The manuscript represents a comprehensive overview conducted between August and November 2024 using the National Library of Medicine browser (Medline, Pub-Med, Web of Science). Full article

Earth’s rotation around its axis has pressured its inhabitants to adapt to 24 h cycles of day and night. Humans adapted their own circadian rhythms to the Earth’s rhythms with a light-aligned awake–sleep cycle. As a consequence, metabolism undergoes drastic changes throughout the circadian cycle and needs plasticity to cope with opposing conditions in the day (when there is an increase in energy demands and food availability), and during the night (when prolonged fasting couples with cyclic changes in the energy demands across the sleep stages). In the last century, human behavior changed dramatically with a disregard for the natural circadian cycles. This misalignment in sleep and eating schedules strongly modulates the metabolism and energy homeostasis, favoring the development of obesity, metabolic syndrome, and metabolic dysfunction-associated steatotic liver disease (MASLD). This review summarizes the effects of circadian disruption, with a particular focus on the feeding and sleep cycles in the development of MASLD and hepatocellular carcinoma. Full article