Asked: How much Melatonin Should I take to enter REM sleep?

So I just had a Lucid Dream and it was sensational. But the thing is it takes forever for me to fall asleep. I try going to sleep at 12am but I just wound up laying there for like 3 or 4 hours until I finally fall asleep. And I'm wondering how much melatonin will it take for me to fall asleep fast and send me into a DEEP rem sleep. I'm assuming I have a little insomnia.