Abstract
Circadian disruption has been observed to be a common factor in the onset of diseases that range from cancer to autoimmunity. This study elucidates that the equatorial region is the only area on our planet not chronotoxic for humans, whereas its constant LD cycle corresponds to the organism’s internal clock cycle and may therefore correctly entrain the circadian rhythm. Chronotoxicity is thus innate and inevitable, considering that the majority of humans lives far from the equator and the circadian rhythm is a congenital physiological feature. Circadian rhythm is an evolutionary mismatch, since innate chronotoxicity is inherently a disadvantage . Innate Chronotoxicity (IC) intensity increases proportionally to the distance from the equator. In the conclusion and open questions section an unconventional external chain of pacemakers and its consequences is debated.