I mean if your at a club or something with no wndows, or if theres a solar eclipse and a blackout at the same time...
Possibilitys are never gonna end
like I said, you
should be able to sit in a completely dark room with absolutely no way to tell time, and still know whether it's night or day
at least, to begin with. of course after a few days of that it'll get confusing
and, like e-maxx said, watches don't even indicate it (usually)