I guess this is maybe what's missing. Ds has always needed a lot of sleep. At three he would take 3 1/2 - 2 1/2 hour naps everyday waking up at his own internal timing in the morning. No melatonin.
Even on weekends, by 2 or 3 in the afternoon he is tired and needs a nap. Especially if its been a busy day. He may sleep until 8 am and still need a nap. He needs the sleep. It's not that he always has issues falling asleep. We've cut the naps back from 4-5:30. We tried no nap and he'd fall asleep in the car. One day he started to fall asleep at school after recess when they turn the lights down. Without a nap he was falling to sleep on the couch at 6:00 or 6:30. It's really hard to work with. His little body needs 12-13 hours. That's just him. On the weekends we don't give melatonin at all. But he still sleeps a lot. The dr was the one who mentioned melatonin to us.
And on the weekends when he wakes up at 8 has a 2 hour nap at 2 or 3 pm and is asleep at 8:30 he is a much easier kid to handle. Much less hyper, much better mood, seems much happier.