How can someone like Adolf Hitler sleep at night with the knowledge that he was responsible for millions of deaths?

Actually, he didn’t sleep very well at night, once he started killing millions of people. He aged very quickly during WWII, and looked at least ten years older than his age by the end of it. At the beginning, he had been a very youthful and energetic looking man who could have passed for ten years younger than late forties. Even a tough and ruthless man like Hitler was brought low by doing so much damage. https://www.quora.com/How-can-someone-like-Adolf-Hitler-sleep-at-night-with-the-knowledge-that-he-was-responsible-for-millions-of-deaths