Actually in Muslim faith, sleep paralysis does exist. It is called karabasan (literally the dark invader). It is explained as a dark being, mostly a malicious genie, sitting on top of you. And it is not associated with being of poor or adequate faith. It might just happen and you are supposed to say out loud the two evil-repelling surahs to get rid of it (which apparently works wonders in terms of fully waking your mind and knocking the awkward sensation off).