Abstract: When installed on a door to a room, e.g. a restroom, or other area where it is desired to monitor occupancy status of the room or other area, a light source (e.g. a light emitting diode) outside the room or area provides a visual signal to those outside the room or area whether it is occupied (flashing) or not (dark). Optionally there is a second light source, or other indicator, inside the room or area that signals, simultaneously with the outside light, to an occupant of the room or area that the device is properly working. Optionally "occupied" and "unoccupied" signals are sent to a remote station to keep a remote observer informed of the occupancy status of an out-of-sight room or area. For example, the remote signalling option can be used by persons to avoid useless trips to a distant restroom that is already occupied. Preferably an infrared sensor mounted in a cylindrical reflector in a casing mounted on the door senses movement of an occupant during a pre-set time period, i.e.