I try not to let mine sleep more than an hour and a half in the day (usually any time between nine and eleven), and he goes to bed around 7:15pm, and is usually up again between 5:45 and 6:30am.
Not long ago though, he was waking in the night and/or up at around 5am. I thought he was getting too much sleep in the day, but it turned out that in his case he was hungry. That came as a complete surprise, because he eats loads in the day!
However, I realised I was giving him his dinner quite early, usually before 5pm, so actually he was going well over 12 hours before eating anything again <guilty emoticon needed here
>, which i know works for some toddlers but not for him. So despite his bedtime milk, there was a big gap before his next meal that stopped him going through the night. Anyway I've started giving him a big yoghurt or banana around 6:30 along with his milk and that has made a really big difference.
Sorry if that's really obvious, though!