Excessive daytime sleepiness in patients with sleep-disordered breathing

To the Editors: I read with interest the article by Mediano et al. 1 about excessive daytime sleepiness (EDS) in patients with obstructive sleep apnoea (OSA). In order to investigate the determinants of EDS in OSA patients, the authors compared the demographics and polysomnographic variables of two groups of OSA patients who had a similar apnoea/hypopnoea index (AHI), age and body mass index (BMI). Nocturnal hypoxaemia was reported to be a major determinant of EDS in patients with OSA. I would like to point out that the possible coexistence of obesity hypoventilation syndrome (OHS), which is a known cause of EDS, was not ruled out in the …