[shardling]

Melatonin intensified my dreams but did not prompt nightmares; but then, I never have nightmares any way!

A friend who was prone to nightmares tried melatonin and it made her nightmares worse.

So perhaps it just induces worse nightmares in those prone to having them in the first place.

[ChristianMarks]

It is a common side effect http://umm.edu/health/medical/altmed/supplement/melatonin possibly dosage related. I have found that 1 mg is more effective than 5 mg, but perhaps I could try .5 mg.