"Your men require food and sleep. We do not!" Ramesis felt like he was stating the obvious. "If your men do not receive these things, their combat performance is adversely affected. We have no such weakness. We can fight for a month on the proteins contained within our armour recycling systems alone. You also suffer from stress-related physical and mental disorders over protracted periods of conflict, which is why I will ignore these insults. Our brothers will stand watch. Please do not question the captain's wisdom again."

Let the Galaxy Burn Anthology pg. 303