[_fnhr]

But this "aren't clearly delineated" gets pedantic sometimes. The same issue is true for assigning hours into morning/day/evening/night, yet no-one talks about issues there. Stratifying something continuous into categories suddenly becomes bad when talking about ethnicity.

[snovv_crash]

That's because the hours don't get personally affected by their classification. I suspect it would suddenly be a big deal if the minimum wage for day vs. night work was different.

And anyways, is 4am morning or night? You'll get different answers in a city compared to on a farm, for example.