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.
yes it’s common. To give you an idea, the biggest news program on public TV uses that format to give a preview of what comes later that evening: https://youtu.be/sAAlQmlmFJU?t=920
google translates “zweiundzwanzig Uhr fünfzehn” to “10:15 pm” but what she says is 22 “hour” 15