Abstract

The relationship between the microbiome and circadian rhythms has emerged as a critical area of biomedical 
research, highlighting the bidirectional communication between host biological clocks and microbial communities. 
Circadian rhythms regulate host metabolic, immune, and neural processes, while gut microbes display their own 
rhythmic fluctuations in composition and function. This dynamic interplay influences nutrient absorption, 
hormonal regulation, immune responses, and neurobehavioral outcomes. Disruptions in circadian patterns, such as 
those caused by shift work, irregular sleep, or dietary changes, can disturb microbial homeostasis and contribute to 
metabolic disorders, immune dysfunction, and neuropsychiatric conditions. Conversely, microbial metabolites act 
as zeitgebers, modulating host circadian gene expression. Understanding these interactions offers potential 
therapeutic strategies, including dietary timing, probiotics, and chronobiology-based interventions, to restore 
host-microbiome synchrony. This review synthesizes current knowledge on the mechanistic links between 
circadian biology and the microbiome, emphasizing their implications for health and disease.