The dorsal sclera may be exposed and prominence of the globe may prevent closure of the eyelids while sleeping (
nocturnal lagophthalmos).
Ah, they can, it's called
nocturnal lagophthalmos — interesting.
This is something that can weird a witness out and has a fancy name:
nocturnal lagophthalmos.
In medical - speaking, people call
it nocturnal lagophthalmos.