Who Really Needs Sleep?

Seems like a silly question, but it has come to light quite often in our home. With kids and taking care of them, "Who Really Needs Sleep?" is what I am asking. When The Boy was born and we brought him home he had trouble eating at first so my wife and I were up pretty much 48 hours straight beyond all the lost sleep in the hospital and what not. We felt like sleep was overrated and were both functioning quite well, until her mom came over to care for the Boy and we crashed hard. There have been other times when we have questioned needing sleep, like currently with both kids sick (actually the Boy is back at school today - YIPPEE!!) we have been up a lot at night while trying to recover ourselves. The Girl has needed aerosol treatments every four hours for at least two days straight. The first night I handled it at 12:00 am and 4:00 am and it went rather smoothly. Then last night I took the 12:00 am and my wife took the 4:00 am, only problem was she was up at 2:00 am, finally getting her back to sleep by 3:10ish am and then the Boy was up 3:30 am to go potty, then the Girl woke up again at 5:40 but just wailed for a moment and went back to sleep. So the question remains, "Who Really Needs Sleep?"