This reminds me of a funny story. For me, it was about 18 hours. I was in graduate school and worked enlessely with 2 other guys on a group project over a long weekend. They left my place at about midnight, but I stayed up all night (2nd sleepless night in a row) to finish the project and turn it in to the Prof by the 10am deadline.
I fell asleep around noon and woke up to pee at about 6 when the sun was going down, so I picked up the phone to call one of the other guys and said, "Dude, just wanted to let you know that I go the paper in on time today..." About then I heard his wife say, "Who in the screw is calling us at 6 in the morning?"
The sun was on it's way up, not down!