I don't think I've ever actually gone more than 25 or 26 hours... However, I spent a summer working at an assisted living home in the Alzheimer's unit-- night shift. So, I would go to work at 10pm and get off at 7am. It was incredibly hard, frustrating, never-ending work. Currently, I am a student and I work a desk job on days when I don't have class... at times, I think I am busy and stressed out-- it simply doesn't not compare to attempting to care for 10 individuals in their last stages of that horrible disease.
Additionally, there is nothing weirder than going to work one day and getting off the next: it messes with your brain.
Anyway-- on a particular morning, we got a call at about 5am. One of the day shifters wasn't going to be in. So, I make a bunch of phone calls in an attempt to find SOMEONE--ANYONE to cover the shift. In the end, I can't. So, I volunteer to take it over. 16 hours of work isn't so bad, right?
So, at 7am, I take over for the day shift. In the end, I will have been there from 10pm one night until 2pm the following day... instead, something goes very wrong. At around 10am, one of the night shift girls calls-- she won't be able to make it in tonight. Somehow, it (once again) became my responsibility to find her replacement. And again, I can't find anybody.
In the end, I fixed the situation by volunteering to work 1/2 of the night shift: 18 hours of hard work in a row. After getting off, I was SO TIRED... and, after driving the 20 miles back home, I couldn't sleep...
LONGEST DAY OF MY LIFE!

(and this post was much longer than it needed to be!)