What's the longest time you went on without sleep and why?

I've quite frequently skipped a night because of random bouts of insomnia, but the worst case was a couple years ago where I just couldn't sleep for two nights in a row. So, about 48 hours awake total. Do not recommend. Definitely not after learning (and experiencing) how vital sleep is. Catch your Z's when you can, folks. You really do need it.