There were two characters preparing for something very dangerous. One of them had done stuff like this before (I'll call him Jim), the other hadn't (I'll call him Bob). They had about ten hours to wait until they were going into the thick of it.
Bob: What are we going to do until it's time?
Jim: I don't know about you, but I'm planning to take a nap.
Bob: A NAP? How can you sleep when we might not be alive in 24 hours?
Jim: Sitting up worrying won't help us. I'd rather be well-rested.
"I didn't have anything else to do, so I took a nap."
It's really not worth worrying about things you have no control over . . . not that that stops anyone :) it's still interesting to think about though.