A head rest accessory for coupling to sockets provided on a bed frame of a hospital bed is provided. A frame is configured to be insertable downwardly into the sockets to couple the frame to the bed frame of the hospital bed. A head rest mount is coupled to the frame and is repositionable along the frame. A head rest is coupled to the head rest mount and includes a face rest shell. A first angle sensor is positioned along a side of the face rest shell. A second angle sensor is positioned on a head end of the face rest shell.