Melatonin

[Angrboda]

Neither have you, apparently.

I've taken melatonin hundreds of times. It's harmless.

That's simply false. You can learn some things from experience. This isn't one of them.

Since you missed my edit, I'll repeat the information:

The available pharmacologic doses of fast-release melatonin (eg, 3 mg) and low-dose slow-release (or controlled) preparations (eg, 0.5 mg) tend to increase hormone levels over a 24-hour period, thus altering the circadian pattern of
circulating melatonin. Abnormally high melatonin levels at night and in the day after consumption of a pharmacologic dose of the hormone may disrupt the delicate mechanism of the circadian system and dissociate mutually
dependent circadian body rhythms, which is described in a recent study. Thus, if administered in high doses or at inappropriate times, melatonin may induce a circadian rhythm disorder rather than cure one.

(source)