How would you say "Are the girls asleep?" instead? Or does that word not exist in this language yet? I could probably think of how one might be done if I knew what exactly the word "asleep" would be on this table http://wiki.dothraki.org/High_Valyrian_Verb_Tables#U-stems . Not that this forum is for discussing that kind of thing. If anyone does want to discuss it you can find me on this forum https://forum.dothraki.org/index.php under the username Caelan.
It is probably translated the same way. I think it's likely that High Valyrian does not use an adjective in the same way as English does in this case. It might be possible to use the participle, and say Riñi ēdruri issi?, but we don't know a lot about if and how the participle is used in a context like this. There might also be a noun form of "sleep" e.g. ēdrunon ("asleep" originally comes from "on sleep", after all) that might be used e.g. Riñi ēdrunot issi? But this is all speculation, I'm afraid.