After pulling an all-nighter and working for around 22 hours, I went to the school I was then teaching at. I thought I was doing my usual thing, i.e. sitting at my workstation that was hooked up to a projector und demonstrating something while explaining what I was doing when one of my students interrupted me to tell me that I wasn’t doing anything that made any sense and on top of that I was slurring my words. I asked the other students whether that was true and they reluctantly agreed. I excused myself and went to the toilet where I had a cry, which is extremely unusual for me. After that, I aborted the lesson and went home where I slept for more than 12 hours. Not a good memory.