Nearly 2.5 days. We had a hectic deadline to meet at work. The second night was one of the most difficult things ive had to put my body through. I started seeing things, sounds were drowned out, slurred speech and i was unsually oversensitive. Red Bull and coffee helped but it got to a point where i had caffeine intoxication. It took me a week to fully recover. The whole experience made me wonder why some idiots even enter no sleep competitions, going 7 days+ without sleep.
There have been weeks were i have had an average of 3 to 4 hours hours sleep per day. The feeling is the similar.