Circadian Regulation of the Immune System and Susceptibility to COVID-19

Circadian rhythms regulate essential physiological processes, including immune responses, and their disruption has been implicated in increased vulnerability to infectious diseases. The importance of circadian health has been highlighted by the COVID-19 pandemic, with studies showing that an infection from SARS-CoV-2 can disturb circadian regulation via changes in clock gene expression and the increase of systemic inflammation. Behavioral changes during the pandemic have worsened circadian inconsistency. Clinically, patients with COVID-19 often show sleep disturbances and changes in circadian biomarkers, which are associated to increasing disease severity and delayed recovery. Studies of mechanisms suggest that circadian disruption reduces antiviral immunity, enhances viral replication, and increases inflammatory responses, which leads to the deterioration of clinical results. Time therapy and other therapies based on circadian rhythms may be utilized after the connection between COVID-19 and these patterns has been established. Studies on such association, along with potential treatments that try to enhance patient health by restoring circadian rhythm, are focused on in this article.