When you go running in the middle of the night and you run and run until you just can't run anymore, so you fall asleep on a bench and you don't know where you are.

When you completely rearrange your room at 3 am when you have work the next morning!
Related: when you show up to work drunk on margaritas!

When you decide to take on a huge research project so you buy tons of textbooks and spend hours researching only to abandon it the next day