Sleep Apnea, Sleepiness, and Driving Risk.

Obstructive sleep apnea is associated with excessive daytime sleepiness in about 50% of cases, and with increased risk of driving accidents. Treatment with continuous positive airway pressure effectively decreases such risk, but compliance with continuous positive airway pressure treatment is often suboptimal. According to the European Union Directive on driving risk, retention of a driving license in patients with obstructive sleep apnea requires assessment of sleepiness and adherence to continuous positive airway pressure treatment, but there remains uncertainty on the optimal methods to assess sleepiness on a large scale.