… and that's probably one great reason why monophasic sleep 'won' in an evolutionary sense. Robustness usually wins out over efficiency, and not being able to stay awake for a few hours to finish a hunt/avoid a predator/avoid freezing to death/etc. is a pretty big reduction in robustness.
That's an important point. The author says that sleeping "is intuitively an evolutionary disadvantage". That's false, the fact that many species do sleep shows that is is an advantage indeed. Otherwise, there would not be these species.
having done it for a year and a half, I heartily agree with that summary. On monophasic sleep I'm able to recover from soreness & illness overnight thanks to the extra sleep buffered in. On polyphasic sleep I'm both more efficient and more vulnerable and as you pointed out, less flexible.
