He's shattered, but fights falling asleep for hours. Happy to snuggle up in bed, but every time he almost drops off, he deliberately wakes himself up, is then hyper for a few min, then quiet until he's almost asleep again. We've had a couple of bad dreams lately but no crying or anything, just coming to us for comfort. Sleeps through normally until usual wake-up time. Why doesn't he want to sleep? What can I do to help him?