A Randomized, Double-blind Clinical Trial showed Adjuvant use of melatonin has a potential to improve clinical symptoms of COVID-19 patients and contribute to a faster return of patients to baseline health.
The pineal gland or epiphysis synthesizes and secretes melatonin, a structurally simple hormone that communicates information about environmental lighting to various parts of the body.
Synthesis and secretion of melatonin is dramatically affected by light exposure to the eyes. The fundamental pattern observed is that serum concentrations of melatonin are low during the daylight hours, and increase to a peak during the dark.
Melatonin has important effects in integrating photoperiod and affecting circadian rhythms.
Refer to https://pubmed.ncbi.nlm.nih.gov/34229896/