Kainulainen S, Duce B, Korkalainen H, et al. - Given a poor correlation of current diagnostic parameters estimating obstructive sleep apnea (OSA) severity with the psychomotor vigilance of OSA patients, researchers sought to examine how the severity of apneas, hypopneas, and intermittent hypoxemia is correlated with impaired vigilance. For this study, Type I polysomnography data and corresponding PVTs of 743 consecutive OSA patients (apnea-hypopnea index (AHI) ≥ 5) were retrospectively reviewed. The odds of prolonged mean and median reaction times, as well as lapse count, raise in correlation with a relative 10% increase in median depth of desaturations. Likewise, a raise in desaturation severity linked with lengthened median reaction time. In all analyses, significant risk factors were female gender, ESS score, and older age. In contrast, no association of increases in conventional AHI, oxygen desaturation index and arousal index with deteriorated PVT performance was observed. Therefore, increased risk of impaired PVT performance was observed in significant correlation with the novel parameters describing the severity of intermittent hypoxemia, but not with conventional OSA severity and sleep fragmentation metrics. These results emphasize the significance of developing the assessment of OSA severity beyond the AHI.