Do you have any evidence that melatonin is not addictive or habit forming? I have not read the studies you have linked; do they explicitly suggest this?

My understanding is that taking melatonin regularly will cause your body to naturally produce less melatonin, especially when taken in the 3mg dosage. Most doctors recommend a dosage of 1mg as that is closer to the body's natural amounts of melatonin.

Anyways, I think it's worth trying melatonin for one of the side effects, weird, vivid, possibly lucid dreams. Or possibly just increased dream recall.