Probiotic consortium supplementation enhances sleep regulation via gut microbiota-derived short-chain fatty acid-mediated metabolic modulation.

Sleep regulation is increasingly recognized as a multifactorial process orchestrated by gut microbial metabolism and gut-brain axis signaling. Whereas pharmacological agents such as diazepam induce transient hypnotic effects through direct receptor modulation, probiotic interventions may elicit broader and more adaptive physiological benefits via host-microbiota metabolic crosstalk. Here, we investigated Limosilactobacillus fermentum SLAM_LAF05 (SLAM_LAF05) and Bifidobacterium longum SLAM_BIL02 (SLAM_BIL02), two rationally selected strains with complementary metabolic capacities, to delineate their synergistic roles in sleep regulation and systemic recovery. Genomic and metabolic profiling revealed that SLAM_LAF05 harbors the arginine deiminase pathway, while SLAM_BIL02 encodes genes for glutamine and glutamate biosynthesis; together, these routes converge on the glutamine/glutamate axis, potentially supporting γ-aminobutyric acid (GABA) synthesis and cellular energy metabolism. In the mouse model, combined LF + BL supplementation prolonged sleep, stabilized sleep-wake architecture, enhanced motor performance, and reduced stress-associated biomarkers. Molecular and immunological analyses demonstrated upregulation of GABAergic genes, a shift toward inhibitory serotonergic signaling, reinforcement of intestinal barrier integrity, and attenuation of inflammatory responses. Microbiome profiling identified Dubosiella as a central taxon positively associated with short-chain fatty acid (SCFA) production, suggesting an association between microbial metabolic activity and host neurotransmitter balance. By integrating genomic, molecular, metabolic, and microbial evidence, this study establishes a systems-level framework illustrating how complementary probiotic metabolisms converge to modulate gut-brain communication, promote sleep stability, and support physiological resilience. These findings provide a conceptual and methodological foundation for investigating future multi-omics approaches to unravel the causal mechanisms underlying probiotic-mediated sleep regulation support the development of scientifically validated probiotic-based functional foods for promoting sleep health.