German version of the Epworth Sleepiness Scale

Background: The Epworth Sleepiness Scale (ESS) is a questionnaire widely used in English speaking countries for assessment of subjective daytime sleepiness. Objective: Our purpose was to translate and validate the ESS for use in German-speaking countries. Methods: A German translation of the ESS was administered to 159 healthy German-speaking Swiss and to 174 patients with various sleep disorders. Results: The mean +/- SD of ESS scores in normals was 5.7 +/- 3.0, in patients it was 13.0 +/- 5.1 (p < 0.001). Scores were not correlated with age or gender but with the percentage of time spent at an oxygen saturation <90% (R = 0.35, p < 0.001), and the respiratory disturbance index (R = 0.26, p < 0.001) in primary snorers and sleep apnea patients. Item analysis confirmed internal consistency of the scale (Cronbach alpha = 0.60 in normals, and 0.83 in patients). Follow-up scores in 25 sleep apnea patients on treatment showed a reduction by 7 +/- 5 points (p < 0.05). Conclusions: Our data validate the ESS for application in German-speaking populations. The simplicity, reliability and the apparent lack of relevant influences of language and cultural background on performance of the ESS makes it a valuable tool for clinical management and research.