I don't have personal experience with it; but my sleep schedule is horrible (I tend to stay up to 5am on alternate nights), so I may give it a try to enforce a normal bedtime, and kick the procrastination monster down a bit (if I don't have the
option of doing the unpleasant work at 2am, it's far easier to force myself to do it during normal hours).
But: see here, this is very relevant: http://hpmor.com/notes/98/
Search MetaMed (a few screens down) for Eliezer Yudkowsky's experience with a sleep disorder (his normal day is 24.5 hours): after spending years trying a whole laundry list of solutions including melatonin, he finally paid MetaMed somewhere north of $5K for their analysis, and got a solution using melatonin that worked (but was not the normal approach to melatonin supplementation).
"their best suggestion, although it had little or no clinical backing, was that I should take my low-dose melatonin 5-7 hours before bedtime, instead of 1-2 hours, a recommendation which I’d never heard anywhere before.
And it worked.
I can’t #&$ing believe that #$%ing worked.
(EDIT in response to reader questions: ”Low-dose” melatonin is 200microgram (mcg) = 0.2 mg. Currently I’m taking 0.2mg 5.5hr in advance, and taking 1mg timed-release just before closing my eyes to sleep. However, I worked up to that over time – I started out just taking 0.3mg total, and I would recommend to anyone else that they start at 0.2mg.)"