A method for monitoring driver alertness in a vehicle is disclosed. Image data representing images of an eye of a driver are obtained, the images having been captured while the driver is operating the vehicle. An eye openness measure of the eye of the driver is computed, based on the image data. A determination is made that the driver is in an unsafe state for driving based on the eye openness measure, and an alert is generated, while the driver is operating the vehicle, based on determining that the driver is in the unsafe state.