Is melatonin secretion governed (partly) by negative feedback?

[Brian Manning Delaney]

Pardon my rather basic question. I did my best to track this down on
my own, but didn't succeed. (Perhaps it isn't known.)

I know melatonin secretion is governed largely by light and possibly
magnetic fields; I'm just wondering if negative feedback may also play
a role. This could be relevant to attempts to use melatonin
supplements therapeutically for sleep disorders, circadian
re-synchronization (for international flight crews), etc.

Any thoughts on this would be appreciated.

Thanks,
Brian Delaney <b-delaney at uchicago.edu>