Paying Attention to Circadian Rhythms in the Treatment of COVID-19

The bidirectional association between the circadian system and innate-adaptive immune functions has been highlighted in many investigations. Viruses are a submicroscopic infectious agent that activate the immune system after entering the human host cell. A novel virus, so-called Coronavirus Disease 2019 (COVID-19), which has recently emerged, is an infectious disease caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Previous investigations show that the factors that are strongly controlled by circadian rhythms, such as clock genes and melatonin, modulate the immune response and may, therefore, influence the healing processes of COVID-19. Moreover, the mechanism of COVID-19 shows that some host cell factors, such as an angiotensin-converting enzyme, exhibit daily rhythms. In this review, we explore key findings that show a link between circadian rhythms and viral infection. The results of these findings could be helpful for clinical and preclinical studies to discover a useful and highly effective treatment for eradicating the COVID-19 disease.