The Efficacy of Eye Blink Rate as an Indicator of Sleepiness: A Study of Simulated Train Driving

Abstract

Despite the steady decline in the number of train incidents in Indonesia, rail safety remains an important national issue. Sleepiness has been cited as a major contributing factor in previous rail accidents, and the ability to detect sleepiness while a machinist is performing his job is of importance. The present investigation aimed at determining if eye blink rate (EBR) could be used in determining the degree of sleepiness during train driving tasks. A group of 12 male subjects were asked to drive a train simulator for 4 h in the morning, with sleep durations of 2, 4, and 8 h were allotted the night before the experiment. The driving task was fairly monotonous, with one stop (train station) for every two hours. A second group was also asked to perform the same tasks, but the driving condition was more dynamic (train stopped every 20 min). A high definition camera was mounted in front of the subjects, and recorded the entire face of the subjects continuously throughout the experiment. Rates of eye blink were determined every 20 min, resulting in 12 data points throughout the experiment. Similarly, scores of Karolinska Sleepiness Scale (KSS) was used to assess perceived sleepiness. Results of this experiment demonstrated that frequency of eye blink tended to increase, but in somewhat inconsistent fashion. KSS scores, on the other hand, increased consistently throughout the experiment. It was concluded here that it was fairly difficult to assess sleepiness based merely on raw blink rate data.