The Innate Chronotoxicity hypothesis: an ubiquitous physiological flaw both unnoticed and inevitable. Could circadian rhythm be an evolutionary mismatch?

Objective: The aim of this study is to outline a flaw in a com-monly scarcely considered physiological adaptation process, which, unnoticed, can lead to severe pathologies that range from cancer to autoimmunity. This being circadian rhythm (CR) disruption a common factor in the onset of such diseases, an additional objective of this paper is to assess whether or not CR is advantageous for organisms and in which conditions that may be and, if disadvantageous, to measure its chronotoxicity. The term "chronotoxicity" is here intended to denote the degree to which the environment desynchronizes the CR of an organism. Methods: An inductive research approach was adopted to integrate, evaluate and interpret the findings of the existing literature to form and verify a new interpretation in the field of research that in this study was named as "Innate Chronotoxicity" (IC) hypothesis. Results: The analysis of the cited literature provided data to derive four empirical assumptions for the attainment of the IC hypothesis, and namely that: the equatorial region is the only area on our planet that is not chronotoxic for humans because its constant LD cycle corresponds to the human organism's internal clock cycle and may therefore correctly entrain the circadian rhythm; chronotoxicity is therefore innate and inevitable considering that the majority of hu-mans live a long way from the equator and the circadian rhythm is a congenital physiological feature of all humans; the circadian rhythm is an evolutionary mismatch since innate chronotoxicity is inherently a disadvantage; IC intensity increases proportionally to the distance a person lives from the equator. Conclusions: Innate chronotoxicity and its causes have remained unnoticed and undetected even to this day, although this study's fin-dings robustly validate the above four assumptions. If this hypothesis is confirmed through further rigorous research, it bears significant implications for the world's healthcare systems, due to the burden placed on them by the estimated population affected and the severity of the resulting related diseases. To entertain further speculation, in the conclusions it is cautiously suggested an expanded view of the circadian pacemaker tree.