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.
I remember. It was a very high-profile study that asserted a phase-delay in the teenage sleep cycle. The study was cited for a while in arguments to shift the school day later by a couple hours.
Full essay: http://www.gwern.net/Melatonin