Dupes use party line phone when they need to sleep

This may be intended, as they don't receive the bonus unless they finish the conversation. I just let them finish, they can make up the sleep in the morning anyway, but if it bothers you you can use a timer sensor to turn the phones off at night.

I might do that, very good solution.

They don't seem to get the bonus from showering if they don't finish either, so I would've expected that from the phones too.

I do recreation after the sleep phase to prevent this. Also happens with the beach chair.