The older wisdom was that you worked on the farm with your husband and children for your entire life, breastfeeding while you peeled the potatoes, putting down your spindle to comfort a crying child. Millers lived in the mill; even blacksmiths lived at their smithies. Except for rituals, separate spheres with separate hard constraints was a novelty of the Satanic mills where the Victorian proletariat toiled.
> they didn't have smartphones to fiddle with in bed
This is solvable for people who want to. We have a dedicated charging station in our house for all electronic devices. Before bed, all of those devices get put there. Including me and my wife's phones.
This definitely is the way to do it. I have started keeping my phone in my living room at night instead of my bedroom, but am still bad about doing this every night. Phones are addictive and it is mentally hard to break out of the addiction. It is essentially a "you just have to do it" situation, but "just do it", while technically simple, is still difficult if you're addicted.
How can you be contacted in case of an emergency in the middle of the night?
I've made my peace with the tiny, tiny chance that I might miss my father's last moments because I didn't hear about his heart attack til the morning, for example.
Living as if it might happen any time and I must be available for it is not healthy IMO.
The phone is still close enough to hear if it rings.
https://www.ou.org/holidays/the_thirty_nine_categories_of_sa... outlines those "clear boundaries" in detail from a pre-medieval or early medieval perspective.
They still had clear boundaries. They slept in the sleeping place and at the sleeping time, they worked at the working place and at the working time. See, they didn't have smartphones to fiddle with in bed.