[Anticlockwise]

I think calling this reprehensible is a bit over judgemental. Melatonin is pretty safe.

For example, there's melatonin in both human and cow milk (more in evening milk, because infants don't have a day night cycle yet, and giving rise to the belief that smells like an urban legend that the old timey advice to drink warm milk if you can't sleep originally came from drinking night time milk fresh from the cow for the melatonin).

Also, you know what causes us to make less melatonin? Light. Blue light especially. Is it equally reprehensible to allow children to exist in houses with led light bulbs, which affects their bodies just as much as a pill?

It seems likely to me that the addition of a small amount of melatonin to replace that lost due to nighttime lights is a reasonable parenting decision. Of course there's uncertainty, but there's uncertainty about everything, can we please stop freaking out as much as we do, as easily as we do?