In article , Paul Weaver
writes
In the old days the cleaners who came round at 8am would notice people
who were absent.

Or early risers aleady at breakfast, or working, or out for a morning run

Your college did breakfast before 8am? I'm impressed. But the bedders
weren't that dumb that they didn't know whose bed had been slept in, or
who were the habitual early risers.
--
"now, the thing you type on and the window you stare out of are the same thing"