Abstract
The European Union (EU) has mandated the installation of the driver drowsiness and attention warning systems (DDAW) in motor vehicles. DDAW must be approved based on the Karolinska Sleepiness Scale (KSS). To validate the Japanese version of the KSS conforming to EU law, participants rated the KSS while performing the psychomotor vigilance test (PVT) and a simulated driving task, during measurement of sleepiness measures. All of the correlation coefficients between the KSS and the sleepiness measures were significant in both the PVT and simulated driving task. These results support the construct validity of the Japanese version of the KSS as a sleepiness measure.
