I have been prescribed melatonin for my "free-running" sleep condition. I take 1mg capsules at 10pm and have taken it for 9 nights. So far, I have stopped going round the clock and managed to fall asleep between 11pm and midnight. But on 6 of these nights I have woken about 3am and been unable to get back to sleep for about 3 hours.Today i did not get back to sleep at all.
I had this problem of fragmented sleep when i took melatonin before at a dose of 3mg, and this has happened to other people on the circadian rhythm list, though not to everyone.
However, it is confounded because
1) I was stressed about Christmas and that could have disturbed my sleep
2) My aunt was staying with me for 3 nights and on at least one occasion she accidentally woke me when she got up in the night
3) I was taking diazepam to cope with the stress and that can affect sleep, plus, now that I have run out, i may get withdrawal effects, which could also affect sleep
4) I feel overloaded by the holidays and run up to that, and don't think I could handle another 2-3 weeks of possible bad sleep for the sake of a trial.
Conclusion: I have decided to abandon the trial for now and resume a normal routine, going around the clock. Then I will try again mid-February, when there are not these confounding factors.

. I have never been "put to sleep" by melatonin. I just find it increases the likelihood that I will be able to get back to sleep when I wake too early in the morning. It tends to keep my thoughts from being "awake" and "racing" when I wake up. Nights that I forget to take it for some reason or another I do notice a difference.