This is what we're working on at https://soundmind.co - improving the efficiency of deep sleep by monitoring your brain for slow wave sleep, and using auditory stimulation to increase delta power.

We're about to begin testing with our first users in the next few weeks.

To answer your question about evolution, I speculate...

1) the evolutionary element was likely only adapted to impact mothers, and still impacts mothers more than fathers. But fathers (I believe) are now more involved.

2) for mothers, less sleep may be linked to less memories of the pain of early child rearing, which may make them more likely to have more children.

Lastly, new mothers had a (if I recall correctly) 15% chance of dying during childbirth or shortly thereafter. From an evolutionary standpoint, the mother had mostly done their job, as long as a village was left to raise the young.

The priority for evolution was to get the child through the first year or so with the mother intact. Beyond that, mother nature didn't prioritize the mothers health over their offspring.