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 suspect it might also depend, among other things, on how closely related those animals are to us. I would likely take your study more seriously if it was done on mammals, and even more so if it was done on primates.
Full essay: http://www.gwern.net/Melatonin