Background:Underlying causes of excessive daytime sleepiness (EDS) are multifactorial including medical and sleep disorders, as well as socio-cultural influences.

Aim: To investigate cultural differences in EDS prevalence in OSA.

Methods: A sample of 6,948 OSA patients from ESADA. The study centres were grouped according to Inglehart-Welzel model: 1) Catholic Europe 2) Protestant Europe 3) English speaking 4) Baltic 5) Polish and 6) Islamic cluster. Clinical, polysomnographic data and EDS (Epworth Sleepiness Scale score -ESS>10) prevalence were compared and multivariable logistic regression was used to identify predictors of EDS controlling for age, sex, lifestyle factors, OSA severity in each of these cultural groups.

Results: Age, gender, BMI, sleep architecture, ESS and OSA severity differed between groups (p<0.001). EDS prevalence was the highest in English speaking (56%), followed by Polish (52%), Islamic (49%), Protestant Europe (42%) and Catholic Europe (40%) (p<0.001).Cultural grouping predicted significant differences in the probability of having EDS (all p<0.001).Furthermore, female gender, younger age, obesity, sleep duration<6 hours and moderate to severe OSA (AHI?15) were significant predictors in Catholic Europe group, younger age in Protestant Europe group, short sleep latency in English speaking group, younger age, obesity, and short sleep latency in Polish group and younger age, sleep duration<6 hours and short sleep latency in Islamic group.

Conclusions: Our results suggest that cultural disparities account for significant heterogeneity in EDS expression among OSA patients.