{Reference Type}: Journal Article {Title}: Circadian rhythm and host genetics. {Author}: Odriozola A;González A;Álvarez-Herms J;Corbi F; {Journal}: Adv Genet {Volume}: 111 {Issue}: 0 {Year}: 2024 {Factor}: 3.88 {DOI}: 10.1016/bs.adgen.2024.02.001 {Abstract}: This chapter aims to explore the usefulness of the latest advances in genetic studies in the field of the circadian system in the future development of individualised strategies for health improvement based on lifestyle intervention. Due to the multifactorial and complex nature of the circadian system, we focus on the highly prevalent phenotypes in the population that are key to understanding its biology from an evolutionary perspective and that can be modulated by lifestyle. Therefore, we leave in the background those phenotypes that constitute infrequent pathologies or in which the current level of scientific evidence does not favour the implementation of practical approaches of this type. Therefore, from an evolutionary paradigm, this chapter addresses phenotypes such as morning chronotypes, evening chronotypes, extreme chronotypes, and other key concepts such as circadian rhythm amplitude, resilience to changes in circadian rhythm, and their relationships with pathologies associated with circadian rhythm imbalances.