A method for monitoring the alertness of the driver of a vehicle, includes continuously detecting and evaluating at least one physical parameter of the driver while the vehicle is in motion, and transmitting a periodic audio signal with a predetermined frequency into a vehicle interior within a predetermined time period if the evaluated physical parameter is in a critical range, whereby the critical range indicates an appropriate level of fatigue of the driver. An apparatus for monitoring the alertness includes a monitoring unit with a sensor unit, which detects at least one physical parameter of the driver, and an evaluation unit, which evaluates the detected physical parameter while the vehicle is in motion. The evaluation unit is coupled to an audio device, which transmits a periodic audio signal into a vehicle interior within a predetermined time if the evaluated physical parameter is in a critical range.