The comparison between pre- and post-lunch driving performance among morning person subjects during a simulated driving

Abstract

Driving fatigue has been widely reported to be one of the main causes of road traffic accidents. One type of driving fatigue is sleep-related fatigue associated with circadian rhythms, such as the phenomenon of a post-lunch dip in performance. In this study, we compared pre- and postlunch driving performance in a simulated driving task using LCT Sim software. We measured reaction time, subjective sleepiness level (Karolinska Sleepiness Scale/KSS), and eye closure pattern (percentage of eye closure/PERCLOS). Participants were 12 healthy young adult males of morning person type. They performed 60 minutes of driving divided into three 20 minutes periods. From the 20 minutes period, all variables were averaged in every 5 minutes. Statistical analysis employed were Paired T-test, one way ANOVA with repeated measures and Pearson product-moment correlation. The postlunch session resulted in greater driving fatigue and worse performance compared to pre-lunch as shown by higher KSS and PERCLOS level and longer reaction time. Significant changes of KSS were only observed in pre-lunch session whereas significant changes of reaction time were only observed in post-lunch indicating a different sensitivity of the two variables. PERCLOS, on the other hand, shows significant changes in both pre- and post-lunch. In correlation analysis, the number of data affects the correlation coefficient as insignificances were observed when the group of data was divided into pre- and post-lunch compared to the total data. As such, future study should involve more subjects using additional measurement systems to get reliable data are important for the development of a fatigue detection system.