I don't take Remeron but take Ambien CR as well as melatonin so I can speak of my experience regarding melatonin.

I was starting to have an issue where I was waking up too early in the morning, especially while taking timed release Ambien CR, so I started researching melatonin and read that our natural sleep regulator declines with age thus increasing the potential for insomnia. When I tried the timed release brand "Source Naturals" melatonin it did absolutely nothing and I even went as far as doubling it and still nothing. Then I read that melatonin brands vary in efficacy and that people were having good results with the timed release brand "Natrol" so I decided to give melatonin a try again. I must say I have noticed a difference with the Natrol brand as I don't wake up early as often as I used to. Also, in addition to efficacy of different brands, I've read melatonin dosages vary with age.

Like all medications, it's hit or miss. Either it works for you or it doesn't. Only going through trial an error will you know for sure.