Wow. Interesting question.
For me it would be what is the longest you ever slept!
I sleep well for a few hours, wake up for a couple and sleep again for a few. So I end up getting six or seven hours every night, but not continuous.
NOT sleeping is something I never suffered.
No answer from my end, but hope you start getting adequate Zzzzzzzz's soon.
One thing I did notice was I absolutely cannot sleep while traveling. When we were going to Japan twice per year, which was a 24 hours door to door travel time, I just could not fall asleep on the flights or in between at terminals either. Even got something from the doctor, that was supposed to help, but all it did was ruin me as far as having a beer during the flights...go figure...