My 3.5 yr old sleeps on average 12 hours. He is exactly like your son. If he naps he goes to bed around 9pm. If he doesn't nap he can fall asleep by 7pm. Generally I try to have to him asleep by 8-8:30. I'm not sure, but I think he naps at school. He rarely naps at home unless he passes out late afternoon or falls asleep in the car. He most often sleeps through the night but he does have times when he wakes. I DO lay with him until he falls asleep at night (i don't care - I will break the habit one day) and the few times he wakes I'll lay with him if need be, but its not often so again, I'll break it when I am ready - LOL. Overtired is wired and cranky (just like for me) so just bc he's overtired doesn't mean he will sleep well...when his imperfect schedule seems to be causing problems, like temper tantrums, then I just try to really focus on making sure a stricter schedule is met...meaning an earlier bedtime and more sleep. He will push it and fight no matter how tired he is, so I just have to remember that I need to get him to sleep! I consider my son a good sleeper overall...but it fluctuates - especially after a crazy holiday season or illness.