I sleep in my makeup almost every night. That was one of the things that drew me to MMU; I am just usually too lazy to wash my face at night (yes, I know that's bad, which is why I quit wearing makeup for many years because it just wasn't worth washing it off at night when nobody important sees me during the day -- I'm a preschool teacher and I rarely see parents or anyone other than coworkers and my kids....and usually I have paint or ink or marker all over me by the end of the day anyway, LOL!) But when I heard the BE infomercial say "so pure you can sleep in it," I said "aha!" They don't recommend it, but seem to claim (from that statement) that it won't hurt. And it really doesn't. I don't know what makes RareMinerals better for sleeping in than their regular "day makeup," but I don't have any problems sleeping in BE, including no pillow transfer and no breakouts.