8 days because I went to a youth boot camp of a sort and I was so fatigued but I couldn't never sleep. As soon as I got home I just slept on my couch for a day or two
5 days when I was a kid because I wanted to break the world record, which at that point I didn't realize could kill me. Recently I had a spell where I couldn't fall asleep no matter how many sedatives I took, and I was up for about 4 days. Absolutely terrible.