I don’t put much stock in psychiatric studies, but sometimes they do make perfectly spot on observations.
My wife had all of our four children at home naturally, and without the use of drugs. She also breastfed the three youngest (couldn’t seem to get the technique right on our eldest).
I can say though, that she’s always been especially sensitive to the cries of our infants. It often would surprise me that they could wake her out of a sound sleep, even when they cried softly.
They’d get me up too, but usually only once they reached the fire siren stage .. LOL
I was exactly as your wife was with my babies, and I delivered all of them via C-section. Go figure. Mine could whimper and I would snap awake and listen to see if there was more coming indicating a need to get up with them. My husband, OTOH, sounds just like you, lol. I can remember mornings sitting holding a finally sleeping infant after being up ALL night with said infant crying throughout the night, feeling like a zombie, and him waking up refreshed and asking if the baby slept ok. He never heard a thing, and our babies slept in OUR bedroom.