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.
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)