This paper presents a non-intrusive algorithm for monitoring and predicting driver vigilance in real time. The proposed technique is applied to a truck driving simulator by monitoring the driver response through steering wheel and accelerator pedal. The simulation results of the truck simulator are validated with a commercial TruckSimĀ® software using identical parameters of a given tractor semitrailer during similar driving conditions. Several distraction indicators are proposed in order to predict the driver distraction, namely the jerk profile, spikiness index and the rate of change for both the steering wheel angle and the accelerator pedal position. The results of several driving experiments emphasise the effectiveness of using steering wheel rate to estimate driver distraction. Moreover, in comparison to other techniques for predicting driver vigilance, the presented work requires low computational power and has a great potential for developing a real-time simple system that can be affordable and reliable.