I noticed this effect really strongly at university. There was one particular lecture hall that was effectively buried in the side of a hill; I can't count how many times I had an early afternoon lecture in there (so it had been in use since 8am), where I just could not focus or stay awake. Assuming sleep deprivation was the problem, afterwards I'd head out and lie down on a bench to take a nap, only to find myself wide awake. I have no trouble taking cat-naps when I'm actually tired, leading me to eventually conclude it was CO2 / O2 in the room that was the culprit.