Can't Sleep

So right now it's 1:47am right now and I'm trying to get myself to sleep. I've always had a difficult time sleeping, I don't know what it is. I would sometimes go through a whole day without caffeine and still find it difficult to sleep at night. I've been using Melatonin to help me sleep which most of the time it does work but recently it seems to not have any effect on me anymore. I should consider seeing a specialist or something.