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.
Context makes it obvious. On the rare occations when it doesn’t, I usually add “in the evening” or “in the morning”