Sleeping With EYES Open

I use to have a cousin that would sleep with his eyes open. Real freaky lookin. I remember being a kid and having sleep overs and noticing that he would sleep with eyes open. At first I thought he was punkin me but later found out he was just a freak LOL. I guess it's a thing some people do. And pets! I've had many pets and especially dogs that have done the same thing. I wonder if do it and don't even know it. Check out this video of this dog sleeping with his eyes open.