@tunared It must be so difficult to sleep ‘with one eye opened.’
When I was working in the hospital, we used bed alarms. They gave off a beep when the patient tried to get up. Check medical supply stores. Also, tucking the covers in tightly on the side of the bed helps. When all else fails, make sure the room is perfectly safe and note lights are available
Is your wife aware that she is getting up at night or is this new?
https://www.thiscaringhome.org/expert-review-bed-chair-sensor-pad-with-voice-alarm/