Hi and welcome to the forum. I'm so sorry your wife has this disease. I don't know if age changes the way these work, so would ask her doctor--but I take Librium in order to shut down and go to sleep. My doctor prescribed 10 mg. capsules, said to take one, and if I wasn't sleep in a half hour, take another. Later, I got a standing prescription of 25 mg.
To end permanent awakening during the middle of the night, I was prescribed Amitriptylene, and I would think your wife should also begin on a low dose (I know it comes in 10 mg.) This is an old medication and used to be called Elavil. It causes some people disorientation during the day, or a "hung over" feeling. I take both Amitriptylene and Librium at 8 pm, and am awake at or by 8 am. I've done this for a long time with no trouble, but do check with her doctor. Also, some folks have initial drowsy days with Amitriptylene which ends in about a week.
Very best wishes. My father lives outside Wilmington, where I went through High School, making you a neighbor of sorts.
Ann