5.30am waking - advice needed!

[mousie]

my son is 22 months old - very small for his age and has been a nightmare to date (colic, poor eater, dairy allergies etc..). He now sleeps through the night but persists at waking at 5.30am - regardless of whether he goes to sleep at 6.30pm or 8.30pm. He sleeps for about an hour and a half in the day. should i be cutting down the day nap - or any tricks for getting him to wake later. it is doing us in completely, and wakes my older daughter too which makes for grumpy days all round. He is pretty wide awake straight away at 5.30 - we give him a bottle around six and then cave in and bring him into our room. I have tried varieties of controlled crying with no success.
anyone any other ideas?

My son is 23 months and has been doing this for some time. He doesn't cry, he whines very loudly. We explained to him that if he didn't cry then he would get a special treat in the morning. As it is December, the special treat is his advent calendar. So far we have had two mornings when he didn't get a special treat and about 5 mornings when we've had to go in to him when he wakes up and remind him that if he doesn't cry he'll get his treat. But he's then been quiet and so got his treat. I'm hoping that by the end of December he'll automatically sleep through!

Sorry, I know I said he doesn't cry, but he calls it crying, hense the phrase (now well known in our house) "no crying, get special treat".