That's a weird condition that you might've seen if you've witnessed someone sleeping with their eyes open.
I've always thought that people with eyeballs protruding a touch too far out of their sockets were afflicted with this. Those people with eyes that almost make them look like they haves Graves' Disease.
Of the few people I've ever had the privilege to see sleeping, one of my best friends and my partner both have the whites of their eyes partially exposed in slumber, which some people find creepy. But oddly, it's grown on as endearingly quirky to me. Maybe I even think of the appearance of this medical condition as cute, since it reminds me of a pug.
My favorite story is when one time when someone with this condition close to me passed out from alcohol intoxication with the whites of his eyes exposed, and someone commented, "I don't know whether to call an ambulance or a priest."
But this makes me realize that we all live some assortment of small and inconsequential medical conditions. None of us are perfect. I personally have weird calluses on my feet, premature spider veins and cracked heels, subtle hearing loss, and mild nerve dullness from sitting a lot.