1. A method for detecting alertness of a driver operating a vehicle, comprising: recording a steering position of the vehicle with a steering sensor; transmitting the recorded steering position to a processor; with the processor, deriving a steering variability based on the recorded steering position of the vehicle over time; calculating a lane variability based on the derived steering variability and a transfer function of the vehicle; and estimating an alertness of the driver based on both the derived steering variability and the calculated lane variability.