Pechanova O, Paulis L, Simko F. Peripheral and central effects of melatonin on blood pressure regulation. Int J Mol Sci. 2014 Oct 8;15(10):17920-37. doi: 10.3390/ijms151017920. PMID: 25299692; PMCID: PMC4227197.

The increased level of serum melatonin observed in some types of hypertension may be a counter-regulatory adaptive mechanism against the sympathetic overstimulation. Since melatonin acts favorably on different levels of hypertension, including organ protection and with minimal side effects, it could become regularly involved in the struggle against this widespread cardiovascular pathology.

https://pubmed.ncbi.nlm.nih.gov/25299692/