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.