LO used to sleep from 7:30 pm to 6:30 am until he recently started waking up at 5:00 am. We don't go in right away, hoping that he will work it out and go back to sleep for a little bit. He goes back down for 5-10 minutes at a time, only to stand up again and whimper that he wants someone to get him. This morning it went on for an hour, with him lying back down, going back to sleep and then standing back up, repeatedly. Any ideas for how to get him back to a more human (for mommy and daddy) wakeup time? He naps well during the day. He eats and drinks well. He's not sick.