Is it possible to overdose on melatonin?

Sure: You can overdose on anything, even water. I normally don't see a role for more than 3mg of melatonin though occasionally i've used 10mg for certain headache and sleep disorders.

OD on Melatonin: Possible, so is true with any medication or supplement at toxic doses.

Few studies done.: "There are very few short-term and no long-term safety data. Toxicological studies have shown that a lethal dose could not be obtained even at extremely high doses. " What that means, is that there may be but we don't know for sure. So don't try it. You would hate to be the "case report" for a serious complication from high dose melatonin. If you feel like harming yourself, please go to the ER