This volume comprehensively covers Circadian Systems Genes and Their Importance for Human Health, Single nucleotide polymorphisms (SNPs) in circadian genes: Impact on Gene Function and Phenotype, Relationship between circadian rhythm and diseases: sex hormones impact, Advances in circadian clock regulation of reproduction, Disruption of the clock gene expression in central and peripheral circadian oscillators by maternal overnutrition in the Oryctolagus cuniculus, COVID-19 disease management in aspect of Circadian system, and more.