I have 2 with severe sleep disturbances. They are on clonodine and used to be on meletonin too (5 mg) with it. They still should be, but we are hoping thing will get better. Not. Meletonin helps them fall asleep but will not keep them that way. Our kids still at 3 and 4 yrs wake 20 times per night. They at least go to sleep now. They used to not sleep at all. I am not sure if people can understand a child that from 4 mos old only sleeps 2 hours per 24-36 hours at a time.
I recommend meletonin 100% and was told by sleep specialists that children can need higher than adult doses for it to work. So, do not get upset if 1 mg does nothing.