The fallacy behind "sleep when the baby sleeps"

Hah! The most common, most accurate, and most impossible to follow advice given to new parents - "sleep when the baby sleeps" Seems like sound advice when you realize babies sleep like 14 hours a day. Naturally, there's the inclination to finally get something other than diaper changes, feeding, brping, playing, and attempting to figure out what's wrong now - but that's not the biggest problem with this advice. No, the biggest problem s that the little booger only sleeps an hour at a time most times! I don't know about you, but it takes me a good15-20 minutes to drop off to sleep - longer if I'm wound up. By the time I'm actually getting into deep sleep, the baby wakes up again. And I feel worse than if I'd just stayed awake! Ugh.