[refurb]

Well the sleep deprivation stage doesn't last that long (although it seems long when going through it) for most babies.

And in terms of one child, your brain (and evolution) does a great job at helping you forget and filter out only the positive experiences of a newborn.

Plus once you've had one, you don't stress nearly as much about the subsequent ones which taxes your brain a lot less. You don't feel quite so exhausted by it and you know it doesn't last forver.