Would any of the OTC stuff even be effective? Melatonin, NAC, and Berberine.
https://pmc.ncbi.nlm.nih.gov/articles/PMC7553080
(no don't, it's hell on earth)
Serotonin is made from tryptophan, which can also be made into niacin.
Taking tryptophan and niacin as a supplement will boost both serotonin and melatonin naturally, assuming these pathways are working properly.
However, this can be dangerous in the presence of an SSRI.