With the current high rates of associated morbidity and mortality, proper management of critical illness
is vital in the treatment of severely ill patients. Disruptions of key body systems stemming from these illnesses may
be attributed to their severity and limited treatment options. Disruption in circadian rhythms caused by critical illnesses
may lead to a decreased patient prognosis, as the biological clocks stemming from circadian rhythms play
several key roles in regulating our internal pathways. This review will highlight how the occurrence of hyperoxic
injury during the progression of critical illness may severely damage circadian rhymicity, and lead to an increased
risk of infection, development of disease, severity of symptoms, morbidity and mortality, and dysregulation of multiple
body systems. Overall, there is strong evidence suggesting that the disruption of circadian rhythms may be caused by critical illness.
Studies performed on several animal models have shown alterations of key genes associated with circadian clock function may heavily
contribute to the increased severity of critical illness linked to circadian disruption. This review will aid in further understanding the link
between circadian disruption and critical illness.