RadioShack makes those nifty wireless alarm systems. It comes with keychain remotes. You can program just the alarm's door/window sensors to go off, or the entire system (motion detectors, too). That might be a handy way for our sleepwalker to get his warning to wake up and retrieve his gun from a safe.
I cant say that it wouldnt bother me if I was in his or his wife's shoes.
Never was a sleepwalker, but I used to be a violent sleeper, I think my cat had a lot to do with it, as he would attack my feet with ninja like speed and agility. Now I just find the lamp on the nightstand knocked off occasionally, along with a pillow in the floor. I dont worry about shooting someone in my sleep.
I do talk in my sleep, but its normally along the lines of "Go the F away," "Leave me the F alone," "turn that F'ing stereo down" and "Shut the F up!" Its aggrevating when you cant get a decent days sleep in your own home.