Our 3.5 yr old has always been a good sleeper (albeit an early waker) - has slept through since he was about 18 mths. In the last couple of weeks he's started waking up around 1am - wide awake, and for the next couple of hours keeps leaping out of bed and calling for us.
Only way to get him back to sleep is to lie down with him for an hour or so till he's deep asleep. Got a 20mth old and am 6mths pregnant so really don't want to get into the habit of this.
Any ideas on how to return him to his previous sleep-through state?