A method/system for lane departure warning/assistance that warns the driver that the vehicle is about to leave a current lane and enter an adjacent lane. The driver is identified, and a corresponding profile is accessed. The driver's pupils may be measured and compared to pupil size baseline data stored in the accessed profile. If the difference in pupil size exceeds a pupil size baseline by more than a deviation level, the method/system may adjust a lane departure warning/assistance threshold of a lane departure detector that warns the driver each time the vehicle is getting too close to an adjacent lane, thus alerting the driver that the vehicle may drift into the next lane. Driving patterns, such as steering angles and braking force, may also be used to adjust the lane departure warning/assistance threshold and determine whether the driver may benefit from lane departure warning/assistance.