Abstract: A vigilance monitoring system and method provides an alarm signal to a subject at an early stage of vigilance loss. The system includes a sensor, preferable made from a piezoelectric material, attached to the eyelid of the subject, that produces an electric signal in response to each eyelid movement, wherein the strength of the signal depends on the magnitude of the eyelid movement. A processor, electrically coupled to the sensor, monitors the frequency of electric signals received having a signal strength above a threshold level corresponding to a small active eyelid movement, and produces an output signal if the frequency of received electric signals having the signal strength above the threshold level is less than a predetermined frequency. The output signal preferably includes an audio alarm signal provided to an output loudspeaker.