Dietary components, including dietary fiber, unsaturated fatty acids, and polyphenols, along with meal timing and spacing, significantly affect the microbiota’s capacity to produce various metabolites essential for quality sleep and overall health. This review explores the role of gut microbiota in regulating sleep through various metabolites such as short-chain fatty acids, tryptophan, serotonin, melatonin, and gamma-aminobutyric acid. A balanced diet rich in plant-based foods enhances the production of these sleep-regulating metabolites, potentially benefiting overall health. This review aims to investigate how dietary habits affect gut microbiota composition, the metabolites it produces, and the subsequent impact on sleep quality and related health conditions.

The recently observed circadian oscillations of the intestinal microbiota underscore the profound nature of the human–microbiome relationship and its importance for health. Together with the discovery of circadian clocks in non-photosynthetic gut bacteria and circadian rhythms in anucleated cells, these findings have indicated the possibility that virtually all microorganisms may possess functional biological clocks. However, they have also raised many essential questions concerning the fundamentals of biological timekeeping, its evolution, and its origin. This narrative review provides a comprehensive overview of the recent literature in molecular chronobiology, aiming to bring together the latest evidence on the structure and mechanisms driving microbial biological clocks while pointing to potential applications of this knowledge in medicine. Moreover, it discusses the latest hypotheses regarding the evolution of timing mechanisms and describes the functions of peroxiredoxins in cells and their contribution to the cellular clockwork. The diversity of biological clocks among various human-associated microorganisms and the role of transcriptional and post-translational timekeeping mechanisms are also addressed. Finally, recent evidence on metabolic oscillators and host–microbiome communication is presented.

Modern society faces a growing prevalence of mental disorders, with stress emerging as a critical factor affecting mental well-being. In recent years, breathwork has gained public and scientific recognition as a promising approach for enhancing psychological health. Despite the rapid growth in research, the field remains fragmented due to the diversity of breathing techniques. Moreover, recent findings have challenged several foundational concepts traditionally believed to underlie the therapeutic effects of breathwork. This review offers a comprehensive overview and comparison of the most widely practiced breathing techniques, with a focus on addressing key theoretical issues. We examine the primary psychophysiological pathways and mechanisms of breathwork, highlighting its influence on the nervous system as central to its effectiveness. We critically evaluate the role of breathing variables, including pace, ratio, breathing route, attention, and the use of biofeedback, in promoting the long-term neurobiological changes that have been associated with improved mental health. We argue that most breathwork techniques share core neurophysiological mechanisms that benefit well-being, regardless of the theoretical differences between specific techniques. Accumulating evidence suggests breathwork may serve as both a preventive and adjunctive therapy for chronic stress, anxiety, and depression, given its potential to target key risk factors and produce clinically relevant outcomes. Contemporary breathwork research, however, is limited by inconsistent study quality and methodological heterogeneity. By synthesizing current evidence and identifying critical knowledge gaps, this review aims to guide future research and advance understanding of breathwork’s therapeutic potential.

Cadmium exposure has been implicated in the development of atherosclerosis, yet its relationship with carotid plaque composition and echogenicity remains poorly understood. A better understanding of the environmental and biological factors influencing plaque characteristics may facilitate more accurate stratification of patients at high risk of ischemic stroke. The aim of this study was to evaluate the relationships between environmental cadmium exposure, plaque calcium content, lifestyle-related factors, and carotid plaque echogenicity, and to assess their combined value for predicting a highly echogenic carotid plaque phenotype. This cross-sectional study included 80 patients with advanced carotid atherosclerosis undergoing carotid endarterectomy. Cadmium concentrations were simultaneously determined in blood, urine, and surgically excised carotid plaques, whereas calcium concentrations were measured in plaque tissue, serum, and urine using atomic absorption spectrometry. Carotid plaque echogenicity was assessed preoperatively using ultrasound-derived Gray-Scale Median (GSM), and multivariable logistic regression models were developed to predict a highly echogenic, stable plaque phenotype. Current smokers exhibited significantly higher blood and urinary cadmium concentrations than never smokers, while urinary cadmium remained elevated after smoking cessation, reflecting cumulative exposure. Plaque calcium content showed the strongest positive association with GSM, whereas cadmium concentrations in blood, urine, and plaque tissue were not independently associated with continuous GSM. Higher fruit and vegetable intake was also positively associated with plaque echogenicity. Integrating cadmium biomarkers, plaque calcium content, smoking-related variables, and dietary factors substantially improved prediction of GSM ≥ 75, achieving excellent discrimination (AUC = 0.870) with 85.0% classification accuracy. These findings suggest that carotid plaque echogenicity reflects the combined influence of local tissue mineralization, environmental exposures, and lifestyle-related factors. This integrative approach may improve our understanding of carotid plaque biology and support future strategies for risk assessment and clinical stratification of patients with carotid atherosclerosis.