Depends on the individuals, and that goes for both ladies and gentlemen. Some want to actually sleep, some don't, some are fine either way. Regardless, sleep expectations (how long, if it's okay to wake the other up, if it's even in the same bed, etc.) should be discussed beforehand. Also make sure to know what both of your food/public time/Scrabble marathon/whatever else you want to do preferences are.
Bottom line: there's a lot of flexibility, and everyone is different, so if one lady isn't interested in the same kind of overnight you are, I'm sure you'll be able to find one who is -- just gotta keep looking.