Are you sure it's not the teething causing it? My DS has never been a great night sleeper, but about 4 months ago he started regularly sleeping through. Then after a couple of months, he was back to waking up. He didn't seem to be in pain or anyhting, and would usually go back to sleep when I went in and tucked him in, but I did have to go in. It only lasted about 3 weeks or so, and what do you know - a few days after he started sleeping again, his last eye tooth came through. Just a thought.