Yes, I have heard of it but never used one. My mother has dementia, in her first stages, something like this might help. But now she is in a home in final stages, not upset or anxious. I have heard of this for dogs, it does calm them down, my daughter used one for her dog, but now that he is older, does not get anxious like when he was younger.
Ask your doctor about it before making a decision to use it or not.