The definitive diagnosis of OSA depended on an in-laboratory overnight polysomnography recording system (Embla, Medcare, Iceland) demonstrating an elevated AHI, which was calculated as the total episodes of hypopnoeas and apnoeas per hour of sleep according to the criteria of the American Academy of Sleep Medicine 1.
The level of daytime sleepiness was assessed using the ESS score in the morning after nocturnal polysomnography. Normal values ranged from 2 to 10, with scores ≥10 indicating daytime sleepiness 11.