Does anyone know a good way to "turn off" your mind so you can go to sleep?

My wife often has a hard time going to sleep. She will be physically exhausted, but her mind continues to run a mile a minute. She has tried Ambien and we have determined she is not allowed to take it anymore. She has bizarre ideas and she acts upon them when she takes Ambien. She has tried melatonin, valerian root, and a variety of herbal remedies all to no avail. She has tried meditation and that just allows her mind to work even more. Any other suggestions?