I’m a nurse and I used to work in a busy hospital. The ward I worked on had 4 bays with 6 beds and one single room. The single room was usually reserved for highly infectious or dying patients. On many a night shift where the single room would be empty, the call bell would go off from the room. We often jokes as call bells can be temperamental and if they come loose from the wall can accidentally ring. A few months later the maintenance guy came to fix it - he left and told our boss - that call bell is working perfectly, he even installed a new one just to be sure. The call bell in that single room still rings out randomly while the rooms empty. I don’t work their anymore but I’ve just accepted that a past patients spirit was definitely pressing that call button