How is it a baby who really should sleep a fair...

How is it a baby who really should sleep a fair bit more then their parents can up stay their parents? My ds is 12 weeks today and i think he wanted to celebrate lol he woke up at 4:30am for a feed and hasnt wanted to go back to sleep since. He has been happy playing on the floor and is full of laughs today. But its been 4 and a half hours since his slept. and im feeling like crap..lol [Edited on 06/01/2009] sorry posted in wrong place [Edited on 06/01/2009]