Solo Circumnavigators (Score 5, Informative)

Polyphasic sleep is used by Solo Circumnavigating sailors. It's the only way to survive. Taking 20 minute catnaps is a lot safer than trying to sleep for hours at a time. Or, for that matter, doing something as dangerous as sailing around the world by yourself while chronicly sleep deprived. I think there was a Nova that talked about this sort of thing a while back.