That happens a lot, I stop working on whatever site/script or image or whatever I am working on at about 3am, decide to have a quick game of Quake 3 or Tony Hawks Pro Skater 2. When I finish my quick game its 8 or 9 am and I end up starting work again.
Only on non-school nights though, on school nights there is no quick game. At 2 or 3 am, thats it, bed time.
Thing is, I absolutely love sleeping, yet, I barely never do it.