I have been taking melatonin for a couple decades, due to severely delayed sleep. I haven't tried anything less than 3mg recently, but that has been very successful. 5mg or more have been too much, although I don't remember the specific problem.
3 mg is also the sweet spot for me. More than about 5 makes me have really wild, restless dreams. I still sleep feel rested in the morning, but it's kind of like you spend the whole night half awake because the dreams are so vivid.
