Parents are supposed to sleep when the baby sleeps. Industrial work culture does not allow this. One of the many things leading the "Western" lifestyle to extinction.
I recall, as a twins dad, I did not have 2+ hours of uninterrupted sleep till they are 2 years old. (This depends on the kid though).
It's my theory that crying evolved as a trait because it forces parents to go find some place safe lest a predator finds them, thus ensuring the helpless kid can grow in safe environments.
Note that there is no mention of sleep in there. That's bonus round if you get it.
Though feeding schedules early on are still grueling.