The main characters in Soul Of The Beast and Awakening Of The Beast, are forced to go without sleep for days. Below are excerpts from the website SLEEPIO:
[How long can we survive without sleep? We don't actually know. What we do know is sleep, like breathing] is a fundamental human requirement. It has even been said that one could survive for three times as long without food as one could without sleep. [One animal experiment] found that depriving rats entirely of sleep resulted in their death, or near-dying state, within 11-32 days…