I have gone >36 hours many times. I think my record is around 50. I did not use any caffeine boost drinks, but I drank quite a bit of pop.
I have friends who are nurses or similar at hospitals who sometimes didn't get any sleep for 3-4 days. They had my admiration.
Lately I've been finding it difficult to do anything and have done a lot of sleeping too. Unfortunately, I kinda need to study... finals this coming week.
Hope this gets sorted out by tomorrow...