Welcome @abbeyc, What you mentioned about Melatonin and inflammation is interesting. I haven't seen that and would love to read it if you can remember where you saw the article. From what I've read, Melatonin possesses anti-inflammatory properties.

"Melatonin has been shown to possess anti-inflammatory effects, among a number of actions. Melatonin reduces tissue destruction during inflammatory reactions by a number of means. Thus melatonin, by virtue of its ability to directly scavenge toxic free radicals, reduces macromolecular damage in all organs."
-- Melatonin and its relation to the immune system and inflammation: https://pubmed.ncbi.nlm.nih.gov/11268363/

Are you currently taking prednisone for your PMR?