Yeah I am flabbergasted a psychiatrist of all people would entertain the idea of a “correct” dose. They should look at their own practice and see the range of lithium, SSRI, antipsychotics, antiepileptics doses their patients are on — and these are for medications with far more studies about dose response than melatonin.

They should also know better that serum levels of a supplement/medication that acts centrally can be misleading.