I spent several months in a monastery. We'd eat one meal a day, alternate between sitting and walking meditation, eventually about two hours, up to ten times each. At the end of each lunar month we'd engage in 'determination' which consisted of no sleep for four days. Aside from believing there were multiple entities in my solitary cell, I generally remained sane and healthy.

In my most productive projects, I go through arbitrary work-crash cycles, perhaps 36 hours awake, who knows how long asleep. Though, I can't imagine it working on a schedule. I failed a semester of University trying to sleep less than four hours each night and couldn't separate my own thoughts from the world around me. Stress and lack of sleep are a hellish combination. Isn't that a well documented torture: sleep deprivation through forced standing, flashing lights, and loud dissonant music, until submission?