Interior light with interior surveillance device

At least one of the lamps (2) illuminating the passenger cabin when a switch (3) is operated is combined with an infrared motion detector. The detector comprises two transmitting elements (7, 8) and a receiver (9). A control unit (10) is connected alternately to one of the transmitters (7, 8) for a predetermined period. The alerting level of the sensor elements (7, 8) can be regulated with an adjusting device (11). The switch (17) for the alarm unit is deactivated when the passenger cabin is occupied.