I did an all-nighter on an international law essay once. Started at 4:00 pm, finished it at 11:30 am the next morning. I was having difficulty distinguishing reality and dreams by the time I got home, and it took about 24 hours to recover.

Last night I had a coffee around midnight, at a 21st birthday, and it must've been stronger than I thought. I got home at half past two, but couldn't sleep till after 6. I've been up that late plenty of times before, but I don't count those as 'all-nighters' because I did, eventually, go to sleep while it was still morning.