Just an idea that a friend did when she was having problems with her son.
She got wind chimes and hung them on his door knob after he went to bed everynight. There was no way he could open the door without them ringing. Oh, she made sure they where the big loud ones, hung 3 on his door. :eek: :D She was dead set on knowing when he opened that door. LOL
Now my brother has these talking door alarms, on his younger childrens door for when they get up in the middle of the night. His one daughter sleep walks, so this way they hear her.
At least this way, maybe, your husband wont have to sleep on the couch till you solve this problem.
good luck to you.