During this past summer I pulled several 48-hour days. This was because I had gotten in a sleep pattern of going to bed at 4-5am and waking up at 2-4pm the next day...which was not very practical. In hopes of shifting to a more normal schedule I tried to just stay up one night and through the entire next day, hoping that I'd get so tired that I'd want to go to sleep at a normal time like 11pm or so. It never really worked, and the feelings I got from the sleep deprivation were very potent.
"The finality of death is the coldest truth one must face. Religion makes the perfect distraction." - Anonymous