I have a nine month old son, we have kept the same routine since he was about 2 weeks old. He doesn't sleep well. he will take two 20 minute naps during the day and most nights sleeps between 5-7 hours. I put him to bed by 830 and he is up by 11. I have tried the whole sleep training thing by not rushing right away but he screams bloody murder and it causes his throat to go hoarse. It takes about an 1-1.5 hours to get him back to sleep but within an hour he is awake again and i repeat the process. He gets up for the day about 630. his regular doctor plus one other think there is nothing wrong and that i need to do the sleep training. I've been working on it for 7 months, and being a single parent its affecting my health as well as his.there must be a problem.
Almost all sleep problems involve the concept of Last Waking Memory. This means that when we fall asleep and then wake up again, for ten million reasons, we prefer the same setting we initially fell asleep in to help us go back to sleep. In terms of kids, this means get them drowsy, do the consistent sleep routine, and then leave the room. He needs to learn to fall asleep on his own (without you being there at all) and if he does this, he will go back to sleep without you being there when he wakes in the middle of the night.
If he seems healthy then he probably is. This is a behavioral problem. Wish I had an easier answer for you.
Good luck, Dr. Olson