What are the important risk factors for excessive daytime sleepiness in a population-based cohort?

Excessive daytime sleepiness (EDS) is a common complaint in the general population and is associated with cardiovascular disease and increased mortality. We aimed to investigate whether sleep duration is related to excessive daytime sleepiness in the general population, both in itself and in combination with other factors. We performed a cross-sectional analysis in the population-based Swedish CArdioPulmonary bioImage Study (SCAPIS) cohort (n = 27,976; 14,436 females; aged 50-64 years) to assess how sleep-related factors along with anthropometric, lifestyle, socioeconomic factors as well as somatic disease and psychological distress, were related with EDS assessed by the Epworth sleepiness scale (ESS). Analyses were performed using logistic regression modelling with EDS defined by an ESS score of ≥11 as the main outcome. Both short and long sleep duration were related to EDS with increasing ORs for decreasing sleep duration (7 h vs. reference (8 h): OR 1.2, 95% CI 1.02-1.3 to ≤4 h: 1.9; 1.4-2.5). In addition to sleep-related factors such as insomnia (1.3; 1.2-1.4), poor sleep quality (1.2; 1.04-1.4), snoring (1.5; 1.4-1.6), and nocturnal gastro-oesophageal reflux (1.5; 1.21-1.8), psychological distress showed a strong association with EDS. This included sadness/depression (1.2; 1.1-1.3), stress (some stress: 1.4; 1.1-1.7 to constant stress over 5 years: 1.7; 1.3-2.2), and self-rated "control in life" (lowest quartile: 1.7; 1.6-2.0). Daytime sleepiness is multifactorial and associated with both sleep duration and sleep quality. Strong associations were also established with factors related to psychological distress. Further research may investigate interventions targeting both sleep and psychological health to reduce daytime sleepiness at the societal level.