Longest ever I stayed awake, I'm not sure.  It was more than 36 hours, possibly 48.  But I did suffer Hallucinations.  I closed my eyes momentarily, and suddenly a lion was rushing me.  Scary stuff if you never had suffered a hallucination before.   
Worst I ever felt the next day from lack of sleep, I was moving, and drove 28 1/2 hours across country only stopping to refuel.  The weather was awful, started in heavy snow, passed through ice rain and fog.  It took me three days before I felt right again.  I don't recommend 1400 mile drives by yourself to anyone.