I discuss melatonin's effects on sleep & its safety; I segue into the general benefits of sleep and the severely disrupted sleep of the modern Western world, the cost of melatonin use and the benefit (eg. enforcing regular bedtimes), followed by a basic cost-benefit analysis of melatonin concluding that the net profit is large enough to be worth giving it a try barring unusual conditions or very pessimistic safety estimates.
Full essay: http://www.gwern.net/Melatonin
I've been using melatonin for years now. I recommended it as part of my health article a while back.
When I started I was careful to always take a <1mg dose. More recently (due to laziness really) I have just been taking whatever dose I found at the store without bothering to break the tablets apart.
Your article reminded me that the current 3mg tabs I have are probably too much. This dose still works fine for me, but I have noticed a higher incidence of headaches which could be connected.
PS, good work on your site gwern, I find your research useful.