Yes they do.
One of mine sleeps upside down, face towards the sand in a hole he dug in the sand. lol
The pair in my 180g sleep upside down as well, face down, against my overflow wall.
They are so cute!
180g- Mostly BIG fish and some coral. ~80g Nuvo- My coral tank with "happy fish"~ 90g- FOWLR Not the not happy type of fish~ 125g- Freshwater Malawi Cichlids ~10g- Nuvo- The refugees from the Ich of '18