Abstract: In order to monitor the movements of a patient who is confined to a bed and to alert supervisory personnel in the event that the patient attempts an unauthorized departure therefrom, an array of radiant energy emitters and a corresponding array of radiant energy detectors are installed in the headboard and in the footboard of the bed. In one embodiment, emitters supply infrared energy to the detectors so as to cover the bed with a blanket of invisible light. When the transmission of infrared energy is interrupted for a predetermined time by an overactive patient, both local and remote warning signals are generated to immediately alert the supervisory personnel to the possibility of impending patient injury.