Construct validity and factor structure of Sinhalese version of Epworth Sleepiness Scale

Objective: This study is the first to validate the Epworth Sleepiness Scale (ESS) in Sri Lanka population. ESS is a tool used to evaluate patients’ habitual sleepiness during the day and is used worldwide. This work examined the psychometric properties of the Sinhalese version of eight items ESS among heavy vehicle drivers in Sri Lanka.Methods: A sample of 403 participants was randomly split into two to evaluate dimensionality by exploratory factor analyses (EFA) and confirmatory factor analyses(CFA).Results: Study findings suggest that the single version of ESS is a reliable and valid instrument for sleep evaluation. The analysis identified two-factor structures for the Sinhalese version of ESS. Factor one included sitting and talking, watching TV, car in traffic, sitting in public and sitting and reading, summarized as sitting and doing something. Factor two included lying down, being a car passenger, and sitting quietly, indicating sitting without engaging in any particular activity.Conclusions: Sinhalese version of the ESS is a bi-dimensional instrument that is reliable and valid for assessing daytime Sleepiness in Sri Lankan heavy vehicle drivers. However, the Sinhalese version of the ESS needs further evaluation among the general population and those with sleep disturbances.