Does arousal frequency predict daytime function?

Patients with the sleep apnoea/hypopnoea syndrome (SANS) have impaired dayt ime function with demonstrable sleepiness and impaired cognition, The hypot hesis that brief arousals From sleep cause these daytime impairments was te sted. One hundred and fifty patients with sleep disordered breathing were studied prospectively, comparing overnight polysomnography with daytime measures o f objective sleepiness, psychological well-being and cognitive performance. Significant, but weak (r(2)<0.1), relatonships were seen between several no cturnal measures (apnoea/hypopnoea index, arousals and desaturation variabl es) and daytime measures of quality of life, well-being, subjective sleepin ess, symptoms and cognitive performance,The only significant relationship b etween nocturnal variables and objective sleepiness was a very weak correla tion (r(2)<0.05) between the lowest oxygen saturation and mean maintenance of wakefulness test (MWT) result, The MWT was better correlated with daytim e function than the multiple sleep latency test. This study shows a lack of strong relationships between conventional nocturnalvariables and objective sleepiness was a very weak correlation (r(2)<0.05) between the lowest oxyg en saturation and mean maintenance of wakefulness test (MWT) result, The MW T was better correlated with daytime function than the multiple sleep laten cy test. This study shows a lack of strong relationships between conventional noctur nal measures and daytime function in patients with sleep disordered breathi ng.