I mean, do they say “I sleep at 9pm” or more like “I sleep at 2100 hrs” even while they are talking informally? 2100 hrs sounds very formal to me, but yeah, I was just wondering if they used 24 hour format for only official and government proceedings and used 12 hour format for casual stuff.
When people talk they speak in the 12 hour clock, but written communication is in 24hr
Wait till you hear how Japan does things. If something closes at 1a or 2a, quite often the signage says 2500 or 2600 instead of 0100 or 0200 to denote that it’s a holdover from the previous day.
Instead of 9pm I would say 21 o’clock (or in German 21 Uhr), if it is obvious I’m talking about the evening, I might also say 9 o’clock (9 Uhr)
Context makes it obvious. On the rare occations when it doesn’t, I usually add “in the evening” or “in the morning”