The influence of age, gender, ethnicity, and insomnia on Epworth sleepiness scores: A normative US population

Background and purpose: This study explored the distribution of Epworth Sleepiness Scale (ESS) scores in a randomly sampled, community population and provided percentile scores that will assist in decision-making in both research and clinical settings. Patients and methods: Participants included 703 individuals between the ages of 20 and 98, with 116 people with insomnia (PWI) and 587 people not having insomnia (PNI). Analyses produced main effects for sleep status and ethnicity. Results: PWI had higher ESS scores than PNI and African-Americans had higher ESS scores than Caucasians, although effect sizes were small. Gender, age group, and season did not impact ESS scores. Receiver operating characteristic (ROC) curve analysis proved the ESS to discriminate poorly between PWI and PNI. Conclusions: This study found higher percentages of 'sleepy' individuals than previous studies. PWI did have slightly elevated scores on the ESS, but this elevation was not necessarily predictive of an insomnia diagnosis. Results support a continuum of sleepiness/alertness among PWI.