Driver sleepiness contributes to a substantial proportion of fatal and severe road crashes and potentially contributes to a greater proportion of less serious crashes. A number of survey studies have reported that some drivers choose to continue to drive while sleepy despite being aware of an increasing level of sleepiness. Additionally, drivers’ motivations to continue driving while sleepy is a stronger predictor of sleepy driving behaviours, overshadowing crash risk perception of sleepy driving. While several survey studies have quantified self-reported aspects of continuing to drive while sleepy, there appears to be lack of studies that examine the actual psychophysiological and performance sequela of continuing to drive when sleepy. The current study sought to examine the effect motivating oneself to apply extra effort to the task of driving when sleepy on physiological and subjective sleepiness and driving performance. In total, 18 participants undertook a 60 minute Hazard Perception test on four occasions – on the four occasions, the participants motivation level (motivated and non-motivated) and sleepiness level (sleepy-alert) were experimentally manipulated. Physiological, subjective, and performance indices of sleepiness were obtained with respect to the effects of the manipulation of motivation and sleepiness levels. The results suggest that no effect of motivation was observed in the Hazard Perception test data. Physiological and subjective sleepiness were both greater in the sleepy conditions than the alert conditions and over the duration of both tests, sleepiness levels increased regardless of the motivation or sleepiness conditions. Considered together, these findings suggest that sleepiness is very resilient to motivations to stay alert and improve performance levels. The present results suggest that continuing to drive while sleepy whereby the drivers motivate themself to apply extra effort to the task of driving is a dangerous driving behaviour
