Epidemiological aspects of obstructive sleep apnea

Obstructive sleep apnea (OSA) is a highly prevalent disorder, characterised by recurrent episodes of upper airway obstruction occurring during sleep, and associated with recurrent cycles of desaturation and re-oxygenation, sympathetic over-activity and intra-thoracic pressure changes, leading to fragmentation of sleep and consequent daytime fatigue and sleepiness (1). OSA is associated with decreased quality of life (QOL), significant functional impairment, and increased risk of road traffic accidents. However, the relationship of OSA with medical co-morbidity, and in particular cardiovascular co-morbidity, is perhaps the area of most interest from a medical perspective (2). This review will discuss several epidemiological aspects of OSA, namely its prevalence, its close relationship with obesity, and its economic impact, alongside a discussion of population-level, epidemiological data evaluating the impact of OSA on cardiovascular and metabolic disease, and its emerging association with cancer