I was a musician and that I was giving a concert at 11pm. I wanted to be fresh for the concert, so I had a nap and woke up on time, but then I opened my computer and saw that my handwatch had the wrong hour, so it was really 1:30am. It was too late to rush, I was already burned. But what would I say? Somehow saying that I confused the hour rather than saying I overslept seemed less bad to me, but was more difficult to explain. I'd have to say I just fell asleep.