be an interaction between melatonin and Prozac (
fluoxetine). Some evidence comes from animal studies, but
how these relate to humans is still unresolved (as far as I know; I been out of the loop for a couple years. In animal studies, melatonin does decrease levels of fluoxetine, but the significance of this is in question.
A molecule related to fluoxetine, fluvoxamine (Luvox) naturally increases blood levels of melatonin.