From my understanding all you really need is like .5 mg. No need for all these crazy mega doses. I have used it on and off after strings of strenuous studying, if I fall asleep within 30 minutes of taking it I wake up feeling well rested in about 6 hours. If I stay awake through the first 30-60 minutes I find it difficult to sleep. This could be because it doesn't actually do much of anything at all and it's all in my head, or for some other reason.
I know that the body starts to produce melatonin with the decrease of light, and my apartment always has lights/screens on and this could also mess with stuff. My experience says it won't hurt you. I also don't recall any "high" or "euphoria" from taking it ever. Max I ever took was 5mg min .5mg and I never noticed much of a difference.