Neurobehavioral functioning in obstructive sleep apnea: differential effects of sleep quality, hypoxemia and subjective sleepiness.

This study evaluated the relationship between neuropsychological and affective functioning, subjective sleepiness and sleep-disordered breathing in 100 patients with obstructive sleep apnea (OSA). Using principal components analysis, three indices of sleep-disordered breathing were identified from polysomnography: sleep disturbance, extent of nocturnal hypoxemia, and sleep quality. Poorer sleep quality was related to slower processing speed, somatic symptomatology and tension-anxiety levels. Nocturnal hypoxemia was related to visuconstructional abilities, processing speed and mental flexibility. Patients who had high levels of subjective sleepiness had poorer performances on a complex task of executive functioning and higher levels of tension-anxiety. These results imply a differential effect of sleep-disordered breathing on domains of neuropsychological functioning. Additionally, they suggest that a patient's subjective level of sleepiness is a good predictor of certain aspects of neurobehavioral functioning.