......and we are very tired!
He occasionally sleeps through so I know he can do it. However, more often then not he wakes between 1-4 times in the night and calls out for us until we go in to him (he's recently gone into a bed but hasn't worked out that he can come through to us yet
). When we go in, we tell him that it is still sleep time and 90% of the time he turns over and goes back to sleep.
He has a good bedtime routine and falls asleep on his own. I don't think he's too hot or cold, his bed is comfortable, he's not hungry and his nappy isn't leaking. I can't work out why he's waking up 
I go through phases, most of the time I am resigned to the fact that his sleep will get better eventually, but every time I hear someone say the phrase 'there are no bad sleepers, only bad habits' I start again down the path of wondering what we can do to sort it out a bit more pro-actively.
Any ideas??