The difference when sleeping compared to resting or low activity work is that sleeping is about 60%-65% of resting from what I've found.[1] I'm not sure why we should assume that shouldn't be a problem. We could be close to a low oxygen situation prior to sleep, and then start sleeping and have hours for it to get worse.
We don't generally design safety regulations around "should" and averages, but instead when edge cases happen, as the magnitude of the outcome is very important to take into consideration. I'm not sure what you're trying to express with your comment.
It's simple: if working for 8 hours with many people is not a problem for the ventilation system, then sleeping with less (residential) people should be no issue at all.
We don't generally design safety regulations around "should" and averages, but instead when edge cases happen, as the magnitude of the outcome is very important to take into consideration. I'm not sure what you're trying to express with your comment.
1: https://www.engineeringtoolbox.com/co2-persons-d_691.html