Duhbya can sleep at night because he lacks any conscience. He can't find any humanity in his enemies. They aren't people. He doesn't just despise them, he thoroughly hates them. He is, like so many others, a Christian in name only.
Duhbya and Darth Cheney and David Addington and John Yoo and Donald Rumsfeld have loosed on our enemies torture. That word is its due and the least we can offer to describe waterboarding. Christopher Hitchens may be easily despised in other venues, but this is how he puts it:
You may have read by now the official lie about this treatment, which is that it “simulates” the feeling of drowning. This is not the case. You feel that you are drowning because you are drowning...Many times before we have described this as torture, as we were learning it from Communist enemies practicing it on us in Korea and Vietnam. At the time, we universally abhorred it. Now many Americans defend it as a necessity, the failed Nuremberg defense, a defense we never accepted when the Chinese did it any more than when the Nazis did.
We said it was a war crime, a crime against humanity. It still is.