I feel certain that there exists an English-language proverb expressing the sentiment, “good conscience produces sound sleep”–only, of course, pithier and more proverbial. 
But my Google-fu is extraordinarily weak today, and now I find myself losing confidence that this proverb does, indeed, exist. Can any savvy Dopers help to soothe my troubled mind?
While it may not be exactly what you are looking for, the one that first comes to my mind is “He/I/Whoever can sleep when the wind blows.” It comes from a story like this, but I read it in a copy of Highlights probably 30 years ago, with a boy as the main character instead of an old man.
how about:
“the sleep of the just” or “no rest for the wicked”
“the sleep of the saved”
One I’ve always liked was, “There are two kinds of people in the world: the takers and the givers. Those who take, eat better. Those who give, sleep better.”
Ooh, I definitely wasn’t explicit enough. I’m sure it emphasizes goodness, so nothing to the effect of “the wicked flourish like the green bay tree.”
And maybe I’m just imagining this, but I seem to think that it’s something you can say quite pointedly to someone with the effect of either complimenting them or insulting them, depending on the circumstances. (A: “God, I only got two hours’ sleep last night.” B: “Well, you know what they say: good conscience produces good sleep [or whatever].”)
“The softest pillow is a clear conscience.”
In the right context, one simply has to say “I can sleep at night”.
As in “my boss in my last job tried to pressure me to do X to our customers, so I quit. I’m unemployed but at least I can sleep at night”.
It’s more often used in the negative.
As in: “taking account of what assholish things that guy does, it’s a wonder he can sleep at night”.