Mary,
When Darcey began to sleep downstairs and I was upstairs, I used baby monitors. At that point in time, Darcey was able to make enough noise that I could hear her and I would wake up. Because it had video and two way communications, I'd look to see if she was moving her head... a sign that she had called me and it wasn't a dream.
Later, as her voice began to lose strength, she was unable to make enough noise to wake me. I asked our ALS Org folks and their technology specialist reached out with a device that sensed minimal movements. For our use, I'd aim it at her left eyebrow... which she could move quite well... even though anything below her neck she had no movement control over. The sensor had an infrared light that the connected device would lock onto our chosen spot. If the underlying spot (in our case, her eyebrow) moved enough, it set of a quite loud buzzer/bell that I could hear through the baby monitor. I'd get up and come investigate to see what the problem might be.
Sure, we had some occasional false alarms when she'd wake and open her eyes wide after a wild dream. But for the most part, it worked exactly as we needed it to. I was able to sleep more soundly and she was comfortable knowing that she could set off the alarm if she needed me for any reason. It was another ALS Org saving loaner closet item. Let me know if you need more particulars and I can point you to the folks that make it... or you can contact your ALS Org folks to see if they happen to have one.
My best...
Jim